large objects - Page 513

How to pass user-defined structs using boost mpi

- by lava

I am trying to send a user-defined structure named ABC using boost::mpi::send () call. The given struct contains a vector "data" whose size is determined at runtime. Objects of struct ABC are sent by master to slaves. But the slaves need to know the size of vector "data" so that the sufficient buffer is available on the slave to receive this data. I can work around it by sending the size first and initialize sufficient buffer on the slave before receiving the objects of struct ABC. But that defeats the whole purpose of using STL containers. Does anyone know of a better way to do handle this ? Any suggestions are greatly appreciated. Here is a sample code that describes the intent of my program. This code fails at runtime due to above mentioned reason. struct ABC { double cur_stock_price; double strike_price; double risk_free_rate; double option_price; std::vector <char> data; }; namespace boost { namespace serialization { template<class Archive> void serialize (Archive &ar, struct ABC &abc, unsigned int version) { ar & abc.cur_stock_price; ar & abc.strike_price; ar & abc.risk_free_rate; ar & abc.option_price; ar & bopr.data; } } } BOOST_IS_MPI_DATATYPE (ABC); int main(int argc, char* argv[]) { mpi::environment env (argc, argv); mpi::communicator world; if (world.rank () == 0) { ABC abc_obj; abc.cur_stock_price = 1.0; abc.strike_price = 5.0; abc.risk_free_rate = 2.5; abc.option_price = 3.0; abc_obj.data.push_back ('a'); abc_obj.data.push_back ('b'); world.send ( 1, ANY_TAG, abc_obj;); std::cout << "Rank 0 OK!" << std::endl; } else if (world.rank () == 1) { ABC abc_obj; // Fails here because abc_obj is not big enough world.recv (0,ANY_TAG, abc_obj;); std::cout << "Rank 1 OK!" << std::endl; for (int i = 0; i < abc_obj;.data.size(); i++) std::cout << i << "=" << abc_obj.data[i] << std::endl; } MPI_Finalize(); return 0; }

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How do you automap List<float> or float[] with Fluent NHibernate?

- by Tom Bushell

Having successfully gotten a sample program working, I'm now starting to do Real Work with Fluent NHibernate - trying to use Automapping on my project's class heirarchy. It's a scientific instrumentation application, and the classes I'm mapping have several properties that are arrays of floats e.g. private float[] _rawY; public virtual float[] RawY { get { return _rawY; } set { _rawY = value; } } These arrays can contain a maximum of 500 values. I didn't expect Automapping to work on arrays, but tried it anyway, with some success at first. Each array was auto mapped to a BLOB (using SQLite), which seemed like a viable solution. The first problem came when I tried to call SaveOrUpdate on the objects containing the arrays - I got "No persister for float[]" exceptions. So my next thought was to convert all my arrays into ILists e.g. public virtual IList<float> RawY { get; set; } But now I get: NHibernate.MappingException: Association references unmapped class: System.Single Since Automapping can deal with lists of complex objects, it never occured to me it would not be able to map lists of basic types. But after doing some Googling for a solution, this seems to be the case. Some people seem to have solved the problem, but the sample code I saw requires more knowledge of NHibernate than I have right now - I didn't understand it. Questions: 1. How can I make this work with Automapping? 2. Also, is it better to use arrays or lists for this application? I can modify my app to use either if necessary (though I prefer lists). Edit: I've studied the code in Mapping Collection of Strings, and I see there is test code in the source that sets up an IList of strings, e.g. public virtual IList<string> ListOfSimpleChildren { get; set; } [Test] public void CanSetAsElement() { new MappingTester<OneToManyTarget>() .ForMapping(m => m.HasMany(x => x.ListOfSimpleChildren).Element("columnName")) .Element("class/bag/element").Exists(); } so this must be possible using pure Automapping, but I've had zero luck getting anything to work, probably because I don't have the requisite knowlege of manually mapping with NHibernate. Starting to think I'm going to have to hack this (by encoding the array of floats as a single string, or creating a class that contains a single float which I then aggregate into my lists), unless someone can tell me how to do it properly. End Edit Here's my CreateSessionFactory method, if that helps formulate a reply... private static ISessionFactory CreateSessionFactory() { ISessionFactory sessionFactory = null; const string autoMapExportDir = "AutoMapExport"; if( !Directory.Exists(autoMapExportDir) ) Directory.CreateDirectory(autoMapExportDir); try { var autoPersistenceModel = AutoMap.AssemblyOf<DlsAppOverlordExportRunData>() .Where(t => t.Namespace == "DlsAppAutomapped") .Conventions.Add( DefaultCascade.All() ) ; sessionFactory = Fluently.Configure() .Database(SQLiteConfiguration.Standard .UsingFile(DbFile) .ShowSql() ) .Mappings(m => m.AutoMappings.Add(autoPersistenceModel) .ExportTo(autoMapExportDir) ) .ExposeConfiguration(BuildSchema) .BuildSessionFactory() ; } catch (Exception e) { Debug.WriteLine(e); } return sessionFactory; }

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Xcode newb -- #include can't find my file

- by morgancodes

I'm trying to get a third party audio library (STK) working inside Xcode. Along with the standard .h files, many of the implementation files include a file called SKINI.msg. SKINI.msg is in the same directory as all of the header files. The header files are getting included fine, but the compiler complains that it can't find SKINI.msg. What do I need to do to get Xcode to happily include SKINI.msg? Edit: Here's the contents of SKINI.msg: /*********************************************************/ /* Definition of SKINI Message Types and Special Symbols Synthesis toolKit Instrument Network Interface These symbols should have the form: \c __SK_<name>_ where <name> is the string used in the SKINI stream. by Perry R. Cook, 1995 - 2010. */ /*********************************************************/ namespace stk { #define NOPE -32767 #define YEP 1 #define SK_DBL -32766 #define SK_INT -32765 #define SK_STR -32764 #define __SK_Exit_ 999 /***** MIDI COMPATIBLE MESSAGES *****/ /*** (Status bytes for channel=0) ***/ #define __SK_NoteOff_ 128 #define __SK_NoteOn_ 144 #define __SK_PolyPressure_ 160 #define __SK_ControlChange_ 176 #define __SK_ProgramChange_ 192 #define __SK_AfterTouch_ 208 #define __SK_ChannelPressure_ __SK_AfterTouch_ #define __SK_PitchWheel_ 224 #define __SK_PitchBend_ __SK_PitchWheel_ #define __SK_PitchChange_ 49 #define __SK_Clock_ 248 #define __SK_SongStart_ 250 #define __SK_Continue_ 251 #define __SK_SongStop_ 252 #define __SK_ActiveSensing_ 254 #define __SK_SystemReset_ 255 #define __SK_Volume_ 7 #define __SK_ModWheel_ 1 #define __SK_Modulation_ __SK_ModWheel_ #define __SK_Breath_ 2 #define __SK_FootControl_ 4 #define __SK_Portamento_ 65 #define __SK_Balance_ 8 #define __SK_Pan_ 10 #define __SK_Sustain_ 64 #define __SK_Damper_ __SK_Sustain_ #define __SK_Expression_ 11 #define __SK_AfterTouch_Cont_ 128 #define __SK_ModFrequency_ __SK_Expression_ #define __SK_ProphesyRibbon_ 16 #define __SK_ProphesyWheelUp_ 2 #define __SK_ProphesyWheelDown_ 3 #define __SK_ProphesyPedal_ 18 #define __SK_ProphesyKnob1_ 21 #define __SK_ProphesyKnob2_ 22 /*** Instrument Family Specific ***/ #define __SK_NoiseLevel_ __SK_FootControl_ #define __SK_PickPosition_ __SK_FootControl_ #define __SK_StringDamping_ __SK_Expression_ #define __SK_StringDetune_ __SK_ModWheel_ #define __SK_BodySize_ __SK_Breath_ #define __SK_BowPressure_ __SK_Breath_ #define __SK_BowPosition_ __SK_PickPosition_ #define __SK_BowBeta_ __SK_BowPosition_ #define __SK_ReedStiffness_ __SK_Breath_ #define __SK_ReedRestPos_ __SK_FootControl_ #define __SK_FluteEmbouchure_ __SK_Breath_ #define __SK_JetDelay_ __SK_FluteEmbouchure_ #define __SK_LipTension_ __SK_Breath_ #define __SK_SlideLength_ __SK_FootControl_ #define __SK_StrikePosition_ __SK_PickPosition_ #define __SK_StickHardness_ __SK_Breath_ #define __SK_TrillDepth_ 1051 #define __SK_TrillSpeed_ 1052 #define __SK_StrumSpeed_ __SK_TrillSpeed_ #define __SK_RollSpeed_ __SK_TrillSpeed_ #define __SK_FilterQ_ __SK_Breath_ #define __SK_FilterFreq_ 1062 #define __SK_FilterSweepRate_ __SK_FootControl_ #define __SK_ShakerInst_ 1071 #define __SK_ShakerEnergy_ __SK_Breath_ #define __SK_ShakerDamping_ __SK_ModFrequency_ #define __SK_ShakerNumObjects_ __SK_FootControl_ #define __SK_Strumming_ 1090 #define __SK_NotStrumming_ 1091 #define __SK_Trilling_ 1092 #define __SK_NotTrilling_ 1093 #define __SK_Rolling_ __SK_Strumming_ #define __SK_NotRolling_ __SK_NotStrumming_ #define __SK_PlayerSkill_ 2001 #define __SK_Chord_ 2002 #define __SK_ChordOff_ 2003 #define __SK_SINGER_FilePath_ 3000 #define __SK_SINGER_Frequency_ 3001 #define __SK_SINGER_NoteName_ 3002 #define __SK_SINGER_Shape_ 3003 #define __SK_SINGER_Glot_ 3004 #define __SK_SINGER_VoicedUnVoiced_ 3005 #define __SK_SINGER_Synthesize_ 3006 #define __SK_SINGER_Silence_ 3007 #define __SK_SINGER_VibratoAmt_ __SK_ModWheel_ #define __SK_SINGER_RndVibAmt_ 3008 #define __SK_SINGER_VibFreq_ __SK_Expression_ } // stk namespace And here's what the compiler said: CompileC build/StkCompile.build/Debug-iphonesimulator/StkCompile.build/Objects-normal/i386/BandedWG.o "../../../Data/study/iPhone class/stk-4.4.2/src/BandedWG.cpp" normal i386 c++ com.apple.compilers.gcc.4_2 cd /Users/morganpackard/Desktop/trashme/StkCompile setenv LANG en_US.US-ASCII setenv PATH "/Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin:/Developer/usr/bin:/usr/bin:/bin:/usr/sbin:/sbin" /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/gcc-4.2 -x c++ -arch i386 -fmessage-length=0 -pipe -Wno-trigraphs -fpascal-strings -fasm-blocks -O0 -Wreturn-type -Wunused-variable -D__IPHONE_OS_VERSION_MIN_REQUIRED=30000 -isysroot /Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator3.1.2.sdk -fvisibility=hidden -fvisibility-inlines-hidden -mmacosx-version-min=10.5 -gdwarf-2 -iquote /Users/morganpackard/Desktop/trashme/StkCompile/build/StkCompile.build/Debug-iphonesimulator/StkCompile.build/StkCompile-generated-files.hmap -I/Users/morganpackard/Desktop/trashme/StkCompile/build/StkCompile.build/Debug-iphonesimulator/StkCompile.build/StkCompile-own-target-headers.hmap -I/Users/morganpackard/Desktop/trashme/StkCompile/build/StkCompile.build/Debug-iphonesimulator/StkCompile.build/StkCompile-all-target-headers.hmap -iquote /Users/morganpackard/Desktop/trashme/StkCompile/build/StkCompile.build/Debug-iphonesimulator/StkCompile.build/StkCompile-project-headers.hmap -F/Users/morganpackard/Desktop/trashme/StkCompile/build/Debug-iphonesimulator -I/Users/morganpackard/Desktop/trashme/StkCompile/build/Debug-iphonesimulator/include -I/Users/morganpackard/Desktop/trashme/StkCompile/build/StkCompile.build/Debug-iphonesimulator/StkCompile.build/DerivedSources/i386 -I/Users/morganpackard/Desktop/trashme/StkCompile/build/StkCompile.build/Debug-iphonesimulator/StkCompile.build/DerivedSources -include /var/folders/dx/dxSUSyOJFv0MBEh9qC1oJ++++TI/-Caches-/com.apple.Xcode.501/SharedPrecompiledHeaders/StkCompile_Prefix-bopqzvwpuyqltrdumgtjtfrjvtzb/StkCompile_Prefix.pch -c "/Users/morganpackard/Desktop/trashme/StkCompile/../../../Data/study/iPhone class/stk-4.4.2/src/BandedWG.cpp" -o /Users/morganpackard/Desktop/trashme/StkCompile/build/StkCompile.build/Debug-iphonesimulator/StkCompile.build/Objects-normal/i386/BandedWG.o /Users/morganpackard/Desktop/trashme/StkCompile/../../../Data/study/iPhone class/stk-4.4.2/src/BandedWG.cpp:33:21: error: SKINI.msg: No such file or directory /Users/morganpackard/Desktop/trashme/StkCompile/../../../Data/study/iPhone class/stk-4.4.2/src/BandedWG.cpp: In member function 'virtual void stk::BandedWG::controlChange(int, stk::StkFloat)': /Users/morganpackard/Desktop/trashme/StkCompile/../../../Data/study/iPhone class/stk-4.4.2/src/BandedWG.cpp:326: error: '__SK_BowPressure_' was not declared in this scope /Users/morganpackard/Desktop/trashme/StkCompile/../../../Data/study/iPhone class/stk-4.4.2/src/BandedWG.cpp:342: error: '__SK_AfterTouch_Cont_' was not declared in this scope /Users/morganpackard/Desktop/trashme/StkCompile/../../../Data/study/iPhone class/stk-4.4.2/src/BandedWG.cpp:349: error: '__SK_ModWheel_' was not declared in this scope /Users/morganpackard/Desktop/trashme/StkCompile/../../../Data/study/iPhone class/stk-4.4.2/src/BandedWG.cpp:357: error: '__SK_ModFrequency_' was not declared in this scope /Users/morganpackard/Desktop/trashme/StkCompile/../../../Data/study/iPhone class/stk-4.4.2/src/BandedWG.cpp:359: error: '__SK_Sustain_' was not declared in this scope /Users/morganpackard/Desktop/trashme/StkCompile/../../../Data/study/iPhone class/stk-4.4.2/src/BandedWG.cpp:363: error: '__SK_Portamento_' was not declared in this scope /Users/morganpackard/Desktop/trashme/StkCompile/../../../Data/study/iPhone class/stk-4.4.2/src/BandedWG.cpp:367: error: '__SK_ProphesyRibbon_' was not declared in this scope

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Python: Improving long cumulative sum

- by Bo102010

I have a program that operates on a large set of experimental data. The data is stored as a list of objects that are instances of a class with the following attributes: time_point - the time of the sample cluster - the name of the cluster of nodes from which the sample was taken code - the name of the node from which the sample was taken qty1 = the value of the sample for the first quantity qty2 = the value of the sample for the second quantity I need to derive some values from the data set, grouped in three ways - once for the sample as a whole, once for each cluster of nodes, and once for each node. The values I need to derive depend on the (time sorted) cumulative sums of qty1 and qty2: the maximum value of the element-wise sum of the cumulative sums of qty1 and qty2, the time point at which that maximum value occurred, and the values of qty1 and qty2 at that time point. I came up with the following solution: dataset.sort(key=operator.attrgetter('time_point')) # For the whole set sys_qty1 = 0 sys_qty2 = 0 sys_combo = 0 sys_max = 0 # For the cluster grouping cluster_qty1 = defaultdict(int) cluster_qty2 = defaultdict(int) cluster_combo = defaultdict(int) cluster_max = defaultdict(int) cluster_peak = defaultdict(int) # For the node grouping node_qty1 = defaultdict(int) node_qty2 = defaultdict(int) node_combo = defaultdict(int) node_max = defaultdict(int) node_peak = defaultdict(int) for t in dataset: # For the whole system ###################################################### sys_qty1 += t.qty1 sys_qty2 += t.qty2 sys_combo = sys_qty1 + sys_qty2 if sys_combo > sys_max: sys_max = sys_combo # The Peak class is to record the time point and the cumulative quantities system_peak = Peak(time_point=t.time_point, qty1=sys_qty1, qty2=sys_qty2) # For the cluster grouping ################################################## cluster_qty1[t.cluster] += t.qty1 cluster_qty2[t.cluster] += t.qty2 cluster_combo[t.cluster] = cluster_qty1[t.cluster] + cluster_qty2[t.cluster] if cluster_combo[t.cluster] > cluster_max[t.cluster]: cluster_max[t.cluster] = cluster_combo[t.cluster] cluster_peak[t.cluster] = Peak(time_point=t.time_point, qty1=cluster_qty1[t.cluster], qty2=cluster_qty2[t.cluster]) # For the node grouping ##################################################### node_qty1[t.node] += t.qty1 node_qty2[t.node] += t.qty2 node_combo[t.node] = node_qty1[t.node] + node_qty2[t.node] if node_combo[t.node] > node_max[t.node]: node_max[t.node] = node_combo[t.node] node_peak[t.node] = Peak(time_point=t.time_point, qty1=node_qty1[t.node], qty2=node_qty2[t.node]) This produces the correct output, but I'm wondering if it can be made more readable/Pythonic, and/or faster/more scalable. The above is attractive in that it only loops through the (large) dataset once, but unattractive in that I've essentially copied/pasted three copies of the same algorithm. To avoid the copy/paste issues of the above, I tried this also: def find_peaks(level, dataset): def grouping(object, attr_name): if attr_name == 'system': return attr_name else: return object.__dict__[attrname] cuml_qty1 = defaultdict(int) cuml_qty2 = defaultdict(int) cuml_combo = defaultdict(int) level_max = defaultdict(int) level_peak = defaultdict(int) for t in dataset: cuml_qty1[grouping(t, level)] += t.qty1 cuml_qty2[grouping(t, level)] += t.qty2 cuml_combo[grouping(t, level)] = (cuml_qty1[grouping(t, level)] + cuml_qty2[grouping(t, level)]) if cuml_combo[grouping(t, level)] > level_max[grouping(t, level)]: level_max[grouping(t, level)] = cuml_combo[grouping(t, level)] level_peak[grouping(t, level)] = Peak(time_point=t.time_point, qty1=node_qty1[grouping(t, level)], qty2=node_qty2[grouping(t, level)]) return level_peak system_peak = find_peaks('system', dataset) cluster_peak = find_peaks('cluster', dataset) node_peak = find_peaks('node', dataset) For the (non-grouped) system-level calculations, I also came up with this, which is pretty: dataset.sort(key=operator.attrgetter('time_point')) def cuml_sum(seq): rseq = [] t = 0 for i in seq: t += i rseq.append(t) return rseq time_get = operator.attrgetter('time_point') q1_get = operator.attrgetter('qty1') q2_get = operator.attrgetter('qty2') timeline = [time_get(t) for t in dataset] cuml_qty1 = cuml_sum([q1_get(t) for t in dataset]) cuml_qty2 = cuml_sum([q2_get(t) for t in dataset]) cuml_combo = [q1 + q2 for q1, q2 in zip(cuml_qty1, cuml_qty2)] combo_max = max(cuml_combo) time_max = timeline.index(combo_max) q1_at_max = cuml_qty1.index(time_max) q2_at_max = cuml_qty2.index(time_max) However, despite this version's cool use of list comprehensions and zip(), it loops through the dataset three times just for the system-level calculations, and I can't think of a good way to do the cluster-level and node-level calaculations without doing something slow like: timeline = defaultdict(int) cuml_qty1 = defaultdict(int) #...etc. for c in cluster_list: timeline[c] = [time_get(t) for t in dataset if t.cluster == c] cuml_qty1[c] = [q1_get(t) for t in dataset if t.cluster == c] #...etc. Does anyone here at Stack Overflow have suggestions for improvements? The first snippet above runs well for my initial dataset (on the order of a million records), but later datasets will have more records and clusters/nodes, so scalability is a concern. This is my first non-trivial use of Python, and I want to make sure I'm taking proper advantage of the language (this is replacing a very convoluted set of SQL queries, and earlier versions of the Python version were essentially very ineffecient straight transalations of what that did). I don't normally do much programming, so I may be missing something elementary. Many thanks!

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SQLAlchemy session management in long-running process

- by codeape

Scenario: A .NET-based application server (Wonderware IAS/System Platform) hosts automation objects that communicate with various equipment on the factory floor. CPython is hosted inside this application server (using Python for .NET). The automation objects have scripting functionality built-in (using a custom, .NET-based language). These scripts call Python functions. The Python functions are part of a system to track Work-In-Progress on the factory floor. The purpose of the system is to track the produced widgets along the process, ensure that the widgets go through the process in the correct order, and check that certain conditions are met along the process. The widget production history and widget state is stored in a relational database, this is where SQLAlchemy plays its part. For example, when a widget passes a scanner, the automation software triggers the following script (written in the application server's custom scripting language): ' wiget_id and scanner_id provided by automation object ' ExecFunction() takes care of calling a CPython function retval = ExecFunction("WidgetScanned", widget_id, scanner_id); ' if the python function raises an Exception, ErrorOccured will be true ' in this case, any errors should cause the production line to stop. if (retval.ErrorOccured) then ProductionLine.Running = False; InformationBoard.DisplayText = "ERROR: " + retval.Exception.Message; InformationBoard.SoundAlarm = True end if; The script calls the WidgetScanned python function: # pywip/functions.py from pywip.database import session from pywip.model import Widget, WidgetHistoryItem from pywip import validation, StatusMessage from datetime import datetime def WidgetScanned(widget_id, scanner_id): widget = session.query(Widget).get(widget_id) validation.validate_widget_passed_scanner(widget, scanner) # raises exception on error widget.history.append(WidgetHistoryItem(timestamp=datetime.now(), action=u"SCANNED", scanner_id=scanner_id)) widget.last_scanner = scanner_id widget.last_update = datetime.now() return StatusMessage("OK") # ... there are a dozen similar functions My question is: How do I best manage SQLAlchemy sessions in this scenario? The application server is a long-running process, typically running months between restarts. The application server is single-threaded. Currently, I do it the following way: I apply a decorator to the functions I make avaliable to the application server: # pywip/iasfunctions.py from pywip import functions def ias_session_handling(func): def _ias_session_handling(*args, **kwargs): try: retval = func(*args, **kwargs) session.commit() return retval except: session.rollback() raise return _ias_session_handling # ... actually I populate this module with decorated versions of all the functions in pywip.functions dynamically WidgetScanned = ias_session_handling(functions.WidgetScanned) Question: Is the decorator above suitable for handling sessions in a long-running process? Should I call session.remove()? The SQLAlchemy session object is a scoped session: # pywip/database.py from sqlalchemy.orm import scoped_session, sessionmaker session = scoped_session(sessionmaker()) I want to keep the session management out of the basic functions. For two reasons: There is another family of functions, sequence functions. The sequence functions call several of the basic functions. One sequence function should equal one database transaction. I need to be able to use the library from other environments. a) From a TurboGears web application. In that case, session management is done by TurboGears. b) From an IPython shell. In that case, commit/rollback will be explicit. (I am truly sorry for the long question. But I felt I needed to explain the scenario. Perhaps not necessary?)

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How to implement an offline reader writer lock

- by Peter Morris

Some context for the question All objects in this question are persistent. All requests will be from a Silverlight client talking to an app server via a binary protocol (Hessian) and not WCF. Each user will have a session key (not an ASP.NET session) which will be a string, integer, or GUID (undecided so far). Some objects might take a long time to edit (30 or more minutes) so we have decided to use pessimistic offline locking. Pessimistic because having to reconcile conflicts would be far too annoying for users, offline because the client is not permanently connected to the server. Rather than storing session/object locking information in the object itself I have decided that any aggregate root that may have its instances locked should implement an interface ILockable public interface ILockable { Guid LockID { get; } } This LockID will be the identity of a "Lock" object which holds the information of which session is locking it. Now, if this were simple pessimistic locking I'd be able to achieve this very simply (using an incrementing version number on Lock to identify update conflicts), but what I actually need is ReaderWriter pessimistic offline locking. The reason is that some parts of the application will perform actions that read these complex structures. These include things like Reading a single structure to clone it. Reading multiple structures in order to create a binary file to "publish" the data to an external source. Read locks will be held for a very short period of time, typically less than a second, although in some circumstances they could be held for about 5 seconds at a guess. Write locks will mostly be held for a long time as they are mostly held by humans. There is a high probability of two users trying to edit the same aggregate at the same time, and a high probability of many users needing to temporarily read-lock at the same time too. I'm looking for suggestions as to how I might implement this. One additional point to make is that if I want to place a write lock and there are some read locks, I would like to "queue" the write lock so that no new read locks are placed. If the read locks are removed withing X seconds then the write lock is obtained, if not then the write lock backs off; no new read-locks would be placed while a write lock is queued. So far I have this idea The Lock object will have a version number (int) so I can detect multi-update conflicts, reload, try again. It will have a string[] for read locks A string to hold the session ID that has a write lock A string to hold the queued write lock Possibly a recursion counter to allow the same session to lock multiple times (for both read and write locks), but not sure about this yet. Rules: Can't place a read lock if there is a write lock or queued write lock. Can't place a write lock if there is a write lock or queued write lock. If there are no locks at all then a write lock may be placed. If there are read locks then a write lock will be queued instead of a full write lock placed. (If after X time the read locks are not gone the lock backs off, otherwise it is upgraded). Can't queue a write lock for a session that has a read lock. Can anyone see any problems? Suggest alternatives? Anything? I'd appreciate feedback before deciding on what approach to take.

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Is SQL Server DRI (ON DELETE CASCADE) slow?

- by Aaronaught

I've been analyzing a recurring "bug report" (perf issue) in one of our systems related to a particularly slow delete operation. Long story short: It seems that the CASCADE DELETE keys were largely responsible, and I'd like to know (a) if this makes sense, and (b) why it's the case. We have a schema of, let's say, widgets, those being at the root of a large graph of related tables and related-to-related tables and so on. To be perfectly clear, deleting from this table is actively discouraged; it is the "nuclear option" and users are under no illusions to the contrary. Nevertheless, it sometimes just has to be done. The schema looks something like this: Widgets | +--- Anvils (1:1) | | | +--- AnvilTestData (1:N) | +--- WidgetHistory (1:N) | +--- WidgetHistoryDetails (1:N) Nothing too scary, really. A Widget can be different types, an Anvil is a special type, so that relationship is 1:1 (or more accurately 1:0..1). Then there's a large amount of data - perhaps thousands of rows of AnvilTestData per Anvil collected over time, dealing with hardness, corrosion, exact weight, hammer compatibility, usability issues, and impact tests with cartoon heads. Then every Widget has a long, boring history of various types of transactions - production, inventory moves, sales, defect investigations, RMAs, repairs, customer complaints, etc. There might be 10-20k details for a single widget, or none at all, depending on its age. So, unsurprisingly, there's a CASCADE DELETE relationship at every level here. If a Widget needs to be deleted, it means something's gone terribly wrong and we need to erase any records of that widget ever existing, including its history, test data, etc. Again, nuclear option. Relations are all indexed, statistics are up to date. Normal queries are fast. The system tends to hum along pretty smoothly for everything except deletes. Getting to the point here, finally, for various reasons we only allow deleting one widget at a time, so a delete statement would look like this: DELETE FROM Widgets WHERE WidgetID = @WidgetID Pretty simple, innocuous looking delete... that takes over 2 minutes to run, for a widget with no data! After slogging through execution plans I was finally able to pick out the AnvilTestData and WidgetHistoryDetails deletes as the sub-operations with the highest cost. So I experimented with turning off the CASCADE (but keeping the actual FK, just setting it to NO ACTION) and rewriting the script as something very much like the following: DECLARE @AnvilID int SELECT @AnvilID = AnvilID FROM Anvils WHERE WidgetID = @WidgetID DELETE FROM AnvilTestData WHERE AnvilID = @AnvilID DELETE FROM WidgetHistory WHERE HistoryID IN ( SELECT HistoryID FROM WidgetHistory WHERE WidgetID = @WidgetID) DELETE FROM Widgets WHERE WidgetID = @WidgetID Both of these "optimizations" resulted in significant speedups, each one shaving nearly a full minute off the execution time, so that the original 2-minute deletion now takes about 5-10 seconds - at least for new widgets, without much history or test data. Just to be absolutely clear, there is still a CASCADE from WidgetHistory to WidgetHistoryDetails, where the fanout is highest, I only removed the one originating from Widgets. Further "flattening" of the cascade relationships resulted in progressively less dramatic but still noticeable speedups, to the point where deleting a new widget was almost instantaneous once all of the cascade deletes to larger tables were removed and replaced with explicit deletes. I'm using DBCC DROPCLEANBUFFERS and DBCC FREEPROCCACHE before each test. I've disabled all triggers that might be causing further slowdowns (although those would show up in the execution plan anyway). And I'm testing against older widgets, too, and noticing a significant speedup there as well; deletes that used to take 5 minutes now take 20-40 seconds. Now I'm an ardent supporter of the "SELECT ain't broken" philosophy, but there just doesn't seem to be any logical explanation for this behaviour other than crushing, mind-boggling inefficiency of the CASCADE DELETE relationships. So, my questions are: Is this a known issue with DRI in SQL Server? (I couldn't seem to find any references to this sort of thing on Google or here in SO; I suspect the answer is no.) If not, is there another explanation for the behaviour I'm seeing? If it is a known issue, why is it an issue, and are there better workarounds I could be using?

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ObjectContext.SaveChanges() fails with SQL CE

- by David Veeneman

I am creating a model-first Entity Framework 4 app that uses SQL CE as its data store. All is well until I call ObjectContext.SaveChanges() to save changes to the entities in the model. At that point, SaveChanges() throws a System.Data.UpdateException, with an inner exception message that reads as follows: Server-generated keys and server-generated values are not supported by SQL Server Compact. I am completely puzzled by this message. Any idea what is going on and how to fix it? Thanks. Here is the Exception dump: System.Data.UpdateException was unhandled Message=An error occurred while updating the entries. See the inner exception for details. Source=System.Data.Entity StackTrace: at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter) at System.Data.EntityClient.EntityAdapter.Update(IEntityStateManager entityCache) at System.Data.Objects.ObjectContext.SaveChanges(SaveOptions options) at System.Data.Objects.ObjectContext.SaveChanges() at FsDocumentationBuilder.ViewModel.Commands.SaveFileCommand.Execute(Object parameter) in D:\Users\dcveeneman\Documents\Visual Studio 2010\Projects\FsDocumentationBuilder\FsDocumentationBuilder\ViewModel\Commands\SaveFileCommand.cs:line 68 at MS.Internal.Commands.CommandHelpers.CriticalExecuteCommandSource(ICommandSource commandSource, Boolean userInitiated) at System.Windows.Controls.Primitives.ButtonBase.OnClick() at System.Windows.Controls.Button.OnClick() at System.Windows.Controls.Primitives.ButtonBase.OnMouseLeftButtonUp(MouseButtonEventArgs e) at System.Windows.UIElement.OnMouseLeftButtonUpThunk(Object sender, MouseButtonEventArgs e) at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget) at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target) at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised) at System.Windows.UIElement.ReRaiseEventAs(DependencyObject sender, RoutedEventArgs args, RoutedEvent newEvent) at System.Windows.UIElement.OnMouseUpThunk(Object sender, MouseButtonEventArgs e) at System.Windows.Input.MouseButtonEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget) at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target) at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs) at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised) at System.Windows.UIElement.RaiseEventImpl(DependencyObject sender, RoutedEventArgs args) at System.Windows.UIElement.RaiseTrustedEvent(RoutedEventArgs args) at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted) at System.Windows.Input.InputManager.ProcessStagingArea() at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input) at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport) at System.Windows.Interop.HwndMouseInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawMouseActions actions, Int32 x, Int32 y, Int32 wheel) at System.Windows.Interop.HwndMouseInputProvider.FilterMessage(IntPtr hwnd, WindowMessage msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at System.Windows.Interop.HwndSource.InputFilterMessage(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.Run() at System.Windows.Application.RunDispatcher(Object ignore) at System.Windows.Application.RunInternal(Window window) at System.Windows.Application.Run(Window window) at System.Windows.Application.Run() at FsDocumentationBuilder.App.Main() in D:\Users\dcveeneman\Documents\Visual Studio 2010\Projects\FsDocumentationBuilder\FsDocumentationBuilder\obj\x86\Debug\App.g.cs:line 50 at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args) at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args) at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly() at System.Threading.ThreadHelper.ThreadStart_Context(Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ThreadHelper.ThreadStart() InnerException: System.Data.EntityCommandCompilationException Message=An error occurred while preparing the command definition. See the inner exception for details. Source=System.Data.Entity StackTrace: at System.Data.Mapping.Update.Internal.UpdateTranslator.CreateCommand(DbModificationCommandTree commandTree) at System.Data.Mapping.Update.Internal.DynamicUpdateCommand.CreateCommand(UpdateTranslator translator, Dictionary`2 identifierValues) at System.Data.Mapping.Update.Internal.DynamicUpdateCommand.Execute(UpdateTranslator translator, EntityConnection connection, Dictionary`2 identifierValues, List`1 generatedValues) at System.Data.Mapping.Update.Internal.UpdateTranslator.Update(IEntityStateManager stateManager, IEntityAdapter adapter) InnerException: System.NotSupportedException Message=Server-generated keys and server-generated values are not supported by SQL Server Compact. Source=System.Data.SqlServerCe.Entity StackTrace: at System.Data.SqlServerCe.SqlGen.DmlSqlGenerator.GenerateReturningSql(StringBuilder commandText, DbModificationCommandTree tree, ExpressionTranslator translator, DbExpression returning) at System.Data.SqlServerCe.SqlGen.DmlSqlGenerator.GenerateInsertSql(DbInsertCommandTree tree, List`1& parameters, Boolean isLocalProvider) at System.Data.SqlServerCe.SqlGen.SqlGenerator.GenerateSql(DbCommandTree tree, List`1& parameters, CommandType& commandType, Boolean isLocalProvider) at System.Data.SqlServerCe.SqlCeProviderServices.CreateCommand(DbProviderManifest providerManifest, DbCommandTree commandTree) at System.Data.SqlServerCe.SqlCeProviderServices.CreateDbCommandDefinition(DbProviderManifest providerManifest, DbCommandTree commandTree) at System.Data.Common.DbProviderServices.CreateCommandDefinition(DbCommandTree commandTree) at System.Data.Common.DbProviderServices.CreateCommand(DbCommandTree commandTree) at System.Data.Mapping.Update.Internal.UpdateTranslator.CreateCommand(DbModificationCommandTree commandTree) InnerException:

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Object hierarchy returned by WCF Service is different than expected

- by robalot

Good Day Everyone... My understanding may be wrong, but I thought once you applied the correct attributes the DataContractSerializer would render fully-qualified instances back to the caller. The code runs and the objects return. But oddly enough, once I look at the returned objects I noticed the namespacing disappeared and the object-hierarchy being exposed through the (web applications) service reference seems to become "flat" (somehow). Now, I expect this from a web-service…but not through WFC. Of course, my understanding of what WFC can do may be wrong. ...please keep in mind I'm still experimenting with all this. So my questions are… Q: Can I do something within the WFC Service to force the namespacing to render through the (service reference) data client proxy? Q: Or perhaps, am I (merely) consuming the service incorrectly? Q: Is this even possible? The service code looks like… [ServiceBehavior(InstanceContextMode = InstanceContextMode.PerSession)] public class DataService : IFishData { public C1FE GetC1FE(Int32 key) { //… more stuff here … } public Project GetProject(Int32 key) { //… more stuff here … } } [ServiceContract] [ServiceKnownType(typeof(wcfFISH.StateManagement.C1FE.New))] [ServiceKnownType(typeof(wcfFISH.StateManagement.Project.New))] public interface IFishData { [OperationContract] C1FE GetC1FE(Int32 key); [OperationContract] Project GetProject(Int32 key); } [DataContract] [KnownType(typeof(wcfFISH.StateManagement.ObjectState))] public class Project { [DataMember] public wcfFISH.StateManagement.ObjectState ObjectState { get; set; } //… more stuff here … } [DataContract] KnownType(typeof(wcfFISH.StateManagement.ObjectState))] public class C1FE { [DataMember] public wcfFISH.StateManagement.ObjectState ObjectState { get; set; } //… more stuff here … } [DataContract(Namespace = "wcfFISH.StateManagement")] [KnownType(typeof(wcfFISH.StateManagement.C1FE.New))] [KnownType(typeof(wcfFISH.StateManagement.Project.New))] public abstract class ObjectState { //… more stuff here … } [DataContract(Namespace = "wcfFISH.StateManagement.C1FE", Name="New")] [KnownType(typeof(wcfFISH.StateManagement.ObjectState))] public class New : ObjectState { //… more stuff here … } [DataContract(Namespace = "wcfFISH.StateManagement.Project", Name = "New")] [KnownType(typeof(wcfFISH.StateManagement.ObjectState))] public class New : ObjectState { //… more stuff here … } The web application code looks like… public partial class Fish_Invite : BaseForm { protected void btnTest_Click(object sender, EventArgs e) { Project project = new Project(); project.Get(base.ProjectKey, base.AsOf); mappers.Project mapProject = new mappers.Project(); srFish.Project fishProject = new srFish.Project(); srFish.FishDataClient fishService = new srFish.FishDataClient(); mapProject.MapTo(project, fishProject); fishProject = fishService.AddProject(fishProject, IUser.UserName); project = null; } } In case I’m not being clear… The issue arises as there is a difference in (the name spacing) that I expect to see (returned) is different from what is actually returned. fishProject.ObjectState should look like... srFish.StateManagement.Project.New fishC1FE.ObjectState should look like... srFish.StateManagement.C1FE.New fishProject.ObjectState looks like... srFish.New1 fishC1FE.ObjectState looks like... srFish.New …“Help me Obi-Wan Kenobi, you’re my only hope!”

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Backbone.js Model change events in nested collections not firing as expected

- by Pallavi Kaushik

I'm trying to use backbone.js in my first "real" application and I need some help debugging why certain model change events are not firing as I would expect. I have a web service at /employees/{username}/tasks which returns a JSON array of task objects, with each task object nesting a JSON array of subtask objects. For example, [{ "id":45002, "name":"Open Dining Room", "subtasks":[ {"id":1,"status":"YELLOW","name":"Clean all tables"}, {"id":2,"status":"RED","name":"Clean main floor"}, {"id":3,"status":"RED","name":"Stock condiments"}, {"id":4,"status":"YELLOW","name":"Check / replenish trays"} ] },{ "id":47003, "name":"Open Registers", "subtasks":[ {"id":1,"status":"YELLOW","name":"Turn on all terminals"}, {"id":2,"status":"YELLOW","name":"Balance out cash trays"}, {"id":3,"status":"YELLOW","name":"Check in promo codes"}, {"id":4,"status":"YELLOW","name":"Check register promo placards"} ] }] Another web service allows me to change the status of a specific subtask in a specific task, and looks like this: /tasks/45002/subtasks/1/status/red [aside - I intend to change this to a HTTP Post-based service, but the current implementation is easier for debugging] I have the following classes in my JS app: Subtask Model and Subtask Collection var Subtask = Backbone.Model.extend({}); var SubtaskCollection = Backbone.Collection.extend({ model: Subtask }); Task Model with a nested instance of a Subtask Collection var Task = Backbone.Model.extend({ initialize: function() { // each Task has a reference to a collection of Subtasks this.subtasks = new SubtaskCollection(this.get("subtasks")); // status of each Task is based on the status of its Subtasks this.update_status(); }, ... }); var TaskCollection = Backbone.Collection.extend({ model: Task }); Task View to renders the item and listen for change events to the model var TaskView = Backbone.View.extend({ tagName: "li", template: $("#TaskTemplate").template(), initialize: function() { _.bindAll(this, "on_change", "render"); this.model.bind("change", this.on_change); }, ... on_change: function(e) { alert("task model changed!"); } }); When the app launches, I instantiate a TaskCollection (using the data from the first web service listed above), bind a listener for change events to the TaskCollection, and set up a recurring setTimeout to fetch() the TaskCollection instance. ... TASKS = new TaskCollection(); TASKS.url = ".../employees/" + username + "/tasks" TASKS.fetch({ success: function() { APP.renderViews(); } }); TASKS.bind("change", function() { alert("collection changed!"); APP.renderViews(); }); // Poll every 5 seconds to keep the models up-to-date. setInterval(function() { TASKS.fetch(); }, 5000); ... Everything renders as expected the first time. But at this point, I would expect either (or both) a Collection change event or a Model change event to get fired if I change a subtask's status using my second web service, but this does not happen. Funnily, I did get change events to fire if I added one additional level of nesting, with the web service returning a single object that has the Tasks Collection embedded, for example: "employee":"pkaushik", "tasks":[{"id":45002,"subtasks":[{"id":1..... But this seems klugey... and I'm afraid I haven't architected my app right. I'll include more code if it helps, but this question is already rather verbose. Thoughts?

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How to determine if two generic type values are equal?

- by comecme

I'm trying to figure out how I can successfully determine if two generic type values are equal to each other. Based on Mark Byers' answer on this question I would think I can just use value.Equals() where value is a generic type. My actual problem is in a LinkedList implementation, but the problem can be shown with this simpler example. class GenericOjbect<T> { public T Value { get; private set; } public GenericOjbect(T value) { Value = value; } public bool Equals(T value) { return (Value.Equals(value)); } } Now I define an instance of GenericObject<StringBuilder> containing new StringBuilder("StackOverflow"). I would expect to get true if I call Equals(new StringBuilder("StackOverflow") on this GenericObject instance, but I get false. A sample program showing this: using System; using System.Text; class Program { static void Main() { var sb1 = new StringBuilder("StackOverflow"); var sb2 = new StringBuilder("StackOverflow"); Console.WriteLine("StringBuilder compare"); Console.WriteLine("1. == " + (sb1 == sb2)); Console.WriteLine("2. Object.Equals " + (Object.Equals(sb1, sb2))); Console.WriteLine("3. this.Equals " + (sb1.Equals(sb2))); var go1 = new GenericOjbect<StringBuilder>(sb1); var go2 = new GenericOjbect<StringBuilder>(sb2); Console.WriteLine("\nGenericObject compare"); Console.WriteLine("1. == " + (go1 == go2)); Console.WriteLine("2. Object.Equals " + (Object.Equals(go1, go2))); Console.WriteLine("3. this.Equals " + (go1.Equals(go2))); Console.WriteLine("4. Value.Equals " + (go1.Value.Equals(go2.Value))); } } For the three methods of comparing two StringBuilder objects, only the StringBuilder.Equals instance method (the third line) returns true. This is what I expected. But when comparing the GenericObject objects, its Equals() method (the third line) returns false. Interestingly enough, the fourth compare method does return true. I'd think the third and fourth comparison are actually doing the same thing. I would have expected true. Because in the Equals() method of the GenericObject class, both value and Value are of type T which in this case is a StringBuilder. Based on Mark Byers' answer in this question, I would've expected the Value.Equals() method to be using the StringBuilder's Equals() method. And as I've shown, the StringBuilder's Equal() method does return true. I've even tried public bool Equals(T value) { return EqualityComparer<T>.Default.Equals(Value, value); } but that also returns false. So, two questions here: Why doesn't the code return true? How could I implement the Equals method so it does return true?

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Objective-C NSArray NEWBIE Question:

- by clearbrian

Hi I have a weird problems with NSArray where some of the members of the objects in my array are going out of scope but not the others: I have a simple object called Section. It has 3 members. @interface Section : NSObject { NSNumber *section_Id; NSNumber *routeId; NSString *startLocationName; } @property(nonatomic,retain) NSNumber *section_Id; @property(nonatomic,retain) NSNumber *routeId; @property(nonatomic,retain) NSString *startLocationName; @end @implementation Section @synthesize section_Id; @synthesize routeId; @synthesize startLocationName; //Some static finder methods to get list of Sections from the db + (NSMutableArray *) findAllSections:{ - (void)dealloc { [section_Id release]; [routeId release]; [startLocationName release]; [super dealloc]; } @end I fill it from a database in a method called findAllSection self.sections = [Section findAllSections]; In find all sections I create some local variables fill them with data from db. NSNumber *secId = [NSNumber numberWithInt:id_section]; NSNumber *rteId = [NSNumber numberWithInt:id_route]; NSString *startName = @""; Then create a new Section and store these local variable's data in the Section Section *section = [[Section alloc] init]; section.section_Id = secId; section.routeId = rteId; section.startLocationName = startName; Then I add the section to the array [sectionsArray addObject:section]; Then I clean up, releasing local variables and the section I added to the array [secId release]; [rteId release]; [startName release]; [locEnd_name release]; [section release]; In a loop repeat for all Sections (release local variables and section is done in every loop) The method returns and I check the array and all the Sections are there. I cant seem to dig further down to see the values of the Section objects in the array (is this possible) Later I try and retrieve one of the Sections I get it from the array Section * section = [self.sections objectAtIndex:row]; Then check the value NSLog(@" SECTION SELECTED:%@",section.section_Id); BUT call to section.section_Id crashed as section.section_Id is out of scope. I check the other members of this Section object and theyre ok. After some trial and error I find that by commenting out the release of the member variable the object is OK. //[secId release]; [rteId release]; [startName release]; [locEnd_name release]; [section release]; My questions are: Am I cleaning up ok? Should I release the object added to an array and the local variable in the function? Is my dealloc ok in Section? Does this code look ok and should I be looking elsewhere for the problem? I'm not doing anything complicated just filling array from DB use it in Table Cell. If its a stupid mistake then tell me (I did put NEWBIE on the question so dont be shocked it was asked) I can comment out the release but would prefer to know why or if code looks ok then ill need further digging. the only place that secId is released is in the dealloc. Thanks

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Why is my code returning a Null Object Refrence error when using WatIn?

- by Fuzz Evans

I keep getting a Null Object Refrence Error, but can't tell why. I have a CSV file that contains 100 urls. The file is read into an array called "lines". public partial class Form1 : System.Windows.Forms.Form { string[] lines; public Form1() ... private void ReadLinksIntoMemory() { //this reads the chosen csv file into our "lines" array //and splits on comma's and new lines to create new objects within the array using (StreamReader sr = new StreamReader(@"C:\temp.csv")) { //reads everything in our csv into 1 long line string fileContents = sr.ReadToEnd(); //splits the 1 long line read in into multiple objects of the lines array lines = fileContents.Split(new string[] { ",", Environment.NewLine }, StringSplitOptions.RemoveEmptyEntries); sr.Dispose(); } } The next part is where I get the null object error. When I try to use WatIn to go to the first item in the lines array it says I'm referencing a null object. private void GoToEditLinks() { for (int i = 0; i < lines.Length; i++) { //go to each link sequentially myIE.GoTo(lines[i].ToString()); //sleep so we can make sure the page loads System.Threading.Thread.Sleep(5000); } } When I debug the code it says that the GoTo request calls lines which is null. It seems like I need to declare the array, but don't I need to tell it an exact size to do that? Example: lines = new string[10] I thought I could use the lines.Length to tell it how big to make the array but that didn't work. What is weird to me is I can use the following code without problem: //returns the accurate number of urls that were in the CSV we read in earlier txtbx1.text = lines.Length; //or //this returns the last entry in the csv, as well as the last entry in the array TextBox2.Text = lines[lines.Length - 1]; I am confused why the array clearly has items in it, they can be called to fill a text box, but when I try to call them in my for loop it says its a null reference? UPDATE: By placing my cursor on both calls to lines and pressing f12 I find they both go to the same instance. The thought next is that I am not calling ReadLinksIntoMemory in time, below is my code: private void button1_Click(object sender, EventArgs e) { button1.Enabled = false; ReadLinksIntoMemory(); GoToEditLinks(); button1.Enabled = true; } Unless I'm mistaken the code says that the ReadLinksIntoMemory method must complete before GoToEditLinks can be called? If ReadLinksIntoMemory didn't finish in time I shouldn't be able to fill my text boxes with the lines array length and/or last entry. UPDATE: Stepping into the method GoToEditLinks() I see that lines is null before it calls: myIE.GoTo(lines[i]); but when it hits the goto command the value changes from null to the url it is suppose to go to, but at that same time it gives me the null object error? UPDATE: I added a IsNullOrEmpty check method and lines array passes it without any issue. I'm beginning to think it is an issue with WatIn and the myIE.GoTo command. I think this is the stack trace/call stack? Program.exe!Program.Form1.GoToEditLinks() Line 284 C# Program.exe!Program.Form1.button1_Click(object sender, System.EventArgs e) Line 191 + 0x8 bytes C# [External Code] Program.exe!Program.Program.Main() Line 18 + 0x1d bytes C# [External Code]

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Linux C++: Linker is outputting strange errors

- by knight666

Alright, here is the output I get: arm-none-linux-gnueabi-ld --entry=main -dynamic-linker=/system/bin/linker -rpath-link=/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib -L/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib -nostdlib -lstdc++ -lm -lGLESv1_CM -rpath=/home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib -rpath=../../YoghurtGum/lib/Android -L./lib/Android intermediate/Alien.o intermediate/Bullet.o intermediate/Game.o intermediate/Player.o ../../YoghurtGum/bin/YoghurtGum.a -o bin/Galaxians.android intermediate/Game.o: In function `Galaxians::Init()': /media/YoghurtGum/Tests/Galaxians/src/Game.cpp:45: undefined reference to `__cxa_end_cleanup' /media/YoghurtGum/Tests/Galaxians/src/Game.cpp:44: undefined reference to `__cxa_end_cleanup' intermediate/Game.o:(.ARM.extab+0x18): undefined reference to `__gxx_personality_v0' intermediate/Game.o: In function `Player::Update()': /media/YoghurtGum/Tests/Galaxians/src/Player.h:41: undefined reference to `__cxa_end_cleanup' intermediate/Game.o:(.ARM.extab.text._ZN6Player6UpdateEv[_ZN6Player6UpdateEv]+0x0): undefined reference to `__gxx_personality_v0' intermediate/Game.o:(.rodata._ZTIN10YoghurtGum4GameE[_ZTIN10YoghurtGum4GameE]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info' intermediate/Game.o:(.rodata._ZTI6Player[_ZTI6Player]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Game.o:(.rodata._ZTIN10YoghurtGum6EntityE[_ZTIN10YoghurtGum6EntityE]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Game.o:(.rodata._ZTIN10YoghurtGum6ObjectE[_ZTIN10YoghurtGum6ObjectE]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info' intermediate/Game.o:(.rodata._ZTI6Bullet[_ZTI6Bullet]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Game.o:(.rodata._ZTI5Alien[_ZTI5Alien]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' intermediate/Game.o:(.rodata+0x20): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' ../../YoghurtGum/bin/YoghurtGum.a(Sprite.o):(.rodata._ZTIN10YoghurtGum16SpriteDataOpenGLE[_ZTIN10YoghurtGum16SpriteDataOpenGLE]+0x0): undefined reference to `vtable for __cxxabiv1::__si_class_type_info' ../../YoghurtGum/bin/YoghurtGum.a(Sprite.o):(.rodata._ZTIN10YoghurtGum10SpriteDataE[_ZTIN10YoghurtGum10SpriteDataE]+0x0): undefined reference to `vtable for __cxxabiv1::__class_type_info' make: *** [bin/Galaxians.android] Fout 1 Here's an error I managed to decipher: intermediate/Game.o: In function `Galaxians::Init()': /media/YoghurtGum/Tests/Galaxians/src/Game.cpp:45: undefined reference to `__cxa_end_cleanup' /media/YoghurtGum/Tests/Galaxians/src/Game.cpp:44: undefined reference to `__cxa_end_cleanup' This is line 43 through 45: Assets::AddSprite(new Sprite("media\\ViperMarkII.bmp"), "ship"); Assets::AddSprite(new Sprite("media\\alien.bmp"), "alien"); Assets::AddSprite(new Sprite("media\\bat_ball.bmp"), "bullet"); So, what seems funny to me is that the first new is fine (line 43), but the second one isn't. What could cause this? intermediate/Game.o: In function `Player::Update()': /media/YoghurtGum/Tests/Galaxians/src/Player.h:41: undefined reference to `__cxa_end_cleanup' Another issue with new: Engine::game->scene_current->AddObject(new Bullet(m_X + 10, m_Y)); I have no idea where to begin with the other issues. These are my makefiles, They're a giant mess because I'm just trying to get it to work. Static library: # ====================================== # # # # YoghurtGum static library # # # # ====================================== # include ../YoghurtGum.mk PROGS = bin/YoghurtGum.a SOURCES = $(wildcard src/*.cpp) #$(YG_PATH_LIB)/libGLESv1_CM.so \ #$(YG_PATH_LIB)/libEGL.so \ YG_LINK_OPTIONS = -shared YG_LIBRARIES = \ $(YG_PATH_LIB)/libc.a \ $(YG_PATH_LIB)/libc.so \ $(YG_PATH_LIB)/libstdc++.a \ $(YG_PATH_LIB)/libstdc++.so \ $(YG_PATH_LIB)/libm.a \ $(YG_PATH_LIB)/libm.so \ $(YG_PATH_LIB)/libui.so \ $(YG_PATH_LIB)/liblog.so \ $(YG_PATH_LIB)/libGLESv2.so \ $(YG_PATH_LIB)/libcutils.so \ YG_OBJECTS = $(patsubst src/%.cpp, $(YG_INT)/%.o, $(SOURCES)) YG_NDK_PATH_LIB = /home/oem/android-ndk-r3/build/platforms/android-5/arch-arm/usr/lib all: $(PROGS) rebuild: clean $(PROGS) # remove all .o objects from intermediate and all .android objects from bin clean: rm -f $(YG_INT)/*.o $(YG_BIN)/*.a copy: acpy ../$(PROGS) $(PROGS): $(YG_OBJECTS) $(YG_ARCHIVER) -vq $(PROGS) $(YG_NDK_PATH_LIB)/crtbegin_static.o $(YG_NDK_PATH_LIB)/crtend_android.o $^ && \ $(YG_ARCHIVER) -vr $(PROGS) $(YG_LIBRARIES) $(YG_OBJECTS): $(YG_INT)/%.o : $(YG_SRC)/%.cpp $(YG_COMPILER) $(YG_FLAGS) -I $(GLES_INCLUDES) -c $< -o $@ Test game project: # ====================================== # # # # Galaxians # # # # ====================================== # include ../../YoghurtGum.mk PROGS = bin/Galaxians.android YG_COMPILER = arm-none-linux-gnueabi-g++ YG_LINKER = arm-none-linux-gnueabi-ld YG_PATH_LIB = ./lib/Android YG_LIBRARIES = ../../YoghurtGum/bin/YoghurtGum.a YG_PROGS = bin/Galaxians.android GLES_INCLUDES = ../../YoghurtGum/src ANDROID_NDK_ROOT = /home/oem/android-ndk-r3 NDK_PLATFORM_VER = 5 YG_NDK_PATH_LIB = $(ANDROID_NDK_ROOT)/build/platforms/android-$(NDK_PLATFORM_VER)/arch-arm/usr/lib YG_LIBS = -nostdlib -lstdc++ -lm -lGLESv1_CM #YG_COMPILE_OPTIONS = -g -rdynamic -Wall -Werror -O2 -w YG_COMPILE_OPTIONS = -g -Wall -Werror -O2 -w YG_LINK_OPTIONS = --entry=main -dynamic-linker=/system/bin/linker -rpath-link=$(YG_NDK_PATH_LIB) -L$(YG_NDK_PATH_LIB) $(YG_LIBS) SOURCES = $(wildcard src/*.cpp) YG_OBJECTS = $(patsubst src/%.cpp, intermediate/%.o, $(SOURCES)) all: $(PROGS) rebuild: clean $(PROGS) clean: rm -f intermediate/*.o bin/*.android $(PROGS): $(YG_OBJECTS) $(YG_LINKER) $(YG_LINK_OPTIONS) -rpath=$(YG_NDK_PATH_LIB) -rpath=../../YoghurtGum/lib/Android -L$(YG_PATH_LIB) $^ $(YG_LIBRARIES) -o $@ $(YG_OBJECTS): intermediate/%.o : src/%.cpp $(YG_COMPILER) $(YG_COMPILE_OPTIONS) -I ../../YoghurtGum/src/GLES -I ../../YoghurtGum/src -c $< -o $@ Any help would be appreciated.

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Adding interactions to admin pages generated by the admin generator

- by Stick it to THE MAN

I am using Symfony 1.2.9 (with Propel ORM) to create a website. I have started using the admin generator to implement the admin functionality. I have come accross a slight 'problem' however. My models are related (e.g. one table may have several 1:N relations and N:N relations). I have not found a way to address this satisfactorily yet. As a tactical solution (for list views), I have decided to simply show the parent object, and then add interactions to show the related objects. I'll use a Blog model to illustrate this. Here are the relationships for a blog model: N:M relationship with Blogroll (models a blog roll) 1:N relationship with Blogpost (models a post submitted to a blog) I had originally intended on displaying the (paged) blogpost list for a blog,, when it was selected, using AJAX, but I am struggling enough with the admin generator as it is, so I have shelved that idea - unless someone is kind enough to shed some light on how to do this. Instead, what I am now doing (as a tactical/interim soln), is I have added interactions to the list view which allow a user to: View a list of the blog roll for the blog on that row View a list of the posts for the blog on that row Add a post for the blog on tha row In all of the above, I have written actions that will basically forward the request to the approriate action (admin generated). However, I need to pass some parameters (like the blog id etc), so that the correct blog roll or blog post list etc is returned. I am sure there is a better way of doing what I want to do, but in case there isn't here are my questions: How may I obtain the object that relates to a specific row (of the clicked link) in the list view (e.g. the blog object in this example) Once I have the object, I may choose to extract various fields: id etc. How can I pass these arguments to the admin generated action ? Regarding the second question, my guess is that this may be the way to do it (I may be wrong) public function executeMyAddedBlogRollInteractionLink(sfWebRequest $request) { // get the object *somehow* (I'm guessing this may work) $object = $this->getRoute()->getObject(); // retrieve the required parameters from the object, and build a query string $query_str=$object->getId(); //forward the request to the generated code (action to display blogroll list in this case) $this->forward('backendmodulename',"getblogrolllistaction?params=$query_string"); } This feels like a bit of a hack, but I'm not sure how else to go about it. I'm also not to keen on sending params (which may include user_id etc via a GET, even a POST is not that much safer, since it is fairly sraightforward to see what requests a browser is making). if there is a better way than what I suggest above to implement this kind of administration that is required for objects with 1 or more M:N relationships, I will be very glad to hear the "recommended" way of going about it. I remember reading about marking certain actions as internal. i.e. callable from only within the app. I wonder if that would be useful in this instance?

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Model Object called in NSOutlineView DataSource Method Crashing App

- by Alec Sloman

I have a bewildering problem, hoping someone can assist: I have a model object, called Road. Here's the interface. @@@ @interface RoadModel : NSObject { NSString *_id; NSString *roadmapID; NSString *routeID; NSString *title; NSString *description; NSNumber *collapsed; NSNumber *isRoute; NSString *staff; NSNumber *start; NSArray *staffList; NSMutableArray *updates; NSMutableArray *uploads; NSMutableArray *subRoads; } @property (nonatomic, copy) NSString *_id; @property (nonatomic, copy) NSString *roadmapID; @property (nonatomic, copy) NSString *routeID; @property (nonatomic, copy) NSString *title; @property (nonatomic, copy) NSString *description; @property (nonatomic, copy) NSNumber *collapsed; @property (nonatomic, copy) NSNumber *isRoute; @property (nonatomic, copy) NSString *staff; @property (nonatomic, copy) NSNumber *start; @property (nonatomic, copy) NSArray *staffList; @property (nonatomic, copy) NSMutableArray *updates; @property (nonatomic, copy) NSMutableArray *uploads; @property (nonatomic, copy) NSMutableArray *subRoads; - (id)initWithJSONObject:(NSDictionary *)JSONObject; @end This part is fine. To give you some background, I'm translating a bunch of JSON into a proper model object so it's easier to work with. Now, I'm trying to display this in an NSOutlineView. This is where the problem is. In particular, I have created the table and a datasource. - (id)initWithRoads:(NSArray *)roads { if (self = [super init]) root = [[NSMutableArray alloc] initWithArray:roads]; return self; } - (NSInteger)outlineView:(NSOutlineView *)outlineView numberOfChildrenOfItem:(id)item { if (item == nil) return root.count; return 0; } - (BOOL)outlineView:(NSOutlineView *)outlineView isItemExpandable:(id)item { return NO; } - (id)outlineView:(NSOutlineView *)outlineView child:(NSInteger)index ofItem:(id)item { if (item == nil) item = root; if (item == root) return [root objectAtIndex:index]; return nil; } - (id)outlineView:(NSOutlineView *)outlineView objectValueForTableColumn:(NSTableColumn *)tableColumn byItem:(id)item { return [item title]; } In the final datasource method, it attempts to return the "title" string property of the model object, but for some reason crashes each time. I have checked that the method is taking in the correct object (I checked [item class] description], and it is the right object), but for some reason if I call any of the objects accessors the app immediately crashes. This is totally puzzling because in the init method, I can iterate through root (an array of RoadModel objects), and print any of its properties without issue. It is only when I'm trying to access the properties in any of the datasource methods that this occurs. I wonder if there is something memory-wise that is going on behind the scenes and I am not providing for it. If you can shed some light on to this situation, it would be greatly appreciated! Thanks in advance!

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Is it possible to embed Cockburn style textual UML Use Case content in the code base to improve code

- by fooledbyprimes

experimenting with Cockburn use cases in code I was writing some complicated UI code. I decided to employ Cockburn use cases with fish,kite,and sea levels (discussed by Martin Fowler in his book 'UML Distilled'). I wrapped Cockburn use cases in static C# objects so that I could test logical conditions against static constants which represented steps in a UI workflow. The idea was that you could read the code and know what it was doing because the wrapped objects and their public contants gave you ENGLISH use cases via namespaces. Also, I was going to use reflection to pump out error messages that included the described use cases. The idea is that the stack trace could include some UI use case steps IN ENGLISH.... It turned out to be a fun way to achieve a mini,psuedo light-weight Domain Language but without having to write a DSL compiler. So my question is whether or not this is a good way to do this? Has anyone out there ever done something similar? c# example snippets follow Assume we have some aspx page which has 3 user controls (with lots of clickable stuff). User must click on stuff in one particular user control (possibly making some kind of selection) and then the UI must visually cue the user that the selection was successful. Now, while that item is selected, the user must browse through a gridview to find an item within one of the other user controls and then select something. This sounds like an easy thing to manage but the code can get ugly. In my case, the user controls all sent event messages which were captured by the main page. This way, the page acted like a central processor of UI events and could keep track of what happens when the user is clicking around. So, in the main aspx page, we capture the first user control's event. using MyCompany.MyApp.Web.UseCases; protected void MyFirstUserControl_SomeUIWorkflowRequestCommingIn(object sender, EventArgs e) { // some code here to respond and make "state" changes or whatever // // blah blah blah // finally we have this (how did we know to call fish level method?? because we knew when we wrote the code to send the event in the user control) UpdateUserInterfaceOnFishLevelUseCaseGoalSuccess(FishLevel.SomeNamedUIWorkflow.SelectedItemForPurchase) } protected void UpdateUserInterfaceOnFishLevelGoalSuccess(FishLevel.SomeNamedUIWorkflow goal) { switch (goal) { case FishLevel.SomeNamedUIWorkflow.NewMasterItemSelected: //call some UI related methods here including methods for the other user controls if necessary.... break; case FishLevel.SomeNamedUIWorkFlow.DrillDownOnDetails: //call some UI related methods here including methods for the other user controls if necessary.... break; case FishLevel.SomeNamedUIWorkFlow.CancelMultiSelect: //call some UI related methods here including methods for the other user controls if necessary.... break; // more cases... } } } //also we have protected void UpdateUserInterfaceOnSeaLevelGoalSuccess(SeaLevel.SomeNamedUIWorkflow goal) { switch (goal) { case SeaLevel.CheckOutWorkflow.ChangedCreditCard: // do stuff // more cases... } } } So, in the MyCompany.MyApp.Web.UseCases namespace we might have code like this: class SeaLevel... class FishLevel... class KiteLevel... The workflow use cases embedded in the classes could be inner classes or static methods or enumerations or whatever gives you the cleanest namespace. I can't remember what I did originally but you get the picture.

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Help with 2-part question on ASP.NET MVC and Custom Security Design

- by JustAProgrammer

I'm using ASP.NET MVC and I am trying to separate a lot of my logic. Eventually, this application will be pretty big. It's basically a SaaS app that I need to allow for different kinds of clients to access. I have a two part question; the first deals with my general design and the second deals with how to utilize in ASP.NET MVC Primarily, there will initially be an ASP.NET MVC "client" front-end and there will be a set of web-services for third parties to interact with (perhaps mobile, etc). I realize I could have the ASP.NET MVC app interact just through the Web Service but I think that is unnecessary overhead. So, I am creating an API that will essentially be a DLL that the Web App and the Web Services will utilize. The API consists of the main set of business logic and Data Transfer Objects, etc. (So, this includes methods like CreateCustomer, EditProduct, etc for example) Also, my permissions requirements are a little complicated. I can't really use a straight Roles system as I need to have some fine-grained permissions (but all permissions are positive rights). So, I don't think I can really use the ASP.NET Roles/Membership system or if I can it seems like I'd be doing more work than rolling my own. I've used Membership before and for this one I think I'd rather roll my own. Both the Web App and Web Services will need to keep security as a concern. So, my design is kind of like this: Each method in the API will need to verify the security of the caller In the Web App, each "page" ("action" in MVC speak) will also check the user's permissions (So, don't present the user with the "Add Customer" button if the user does not have that right but also whenever the API receives AddCustomer(), check the security too) I think the Web Service really needs the checking in the DLL because it may not always be used in some kind of pre-authenticated context (like using Session/Cookies in a Web App); also having the security checks in the API means I don't really HAVE TO check it in other places if I'm on a mobile (say iPhone) and don't want to do all kinds of checking on the client However, in the Web App I think there will be some duplication of work since the Web App checks the user's security before presenting the user with options, which is ok, but I was thinking of a way to avoid this duplication by allowing the Web App to tell the API not check the security; while the Web Service would always want security to be verified Is this a good method? If not, what's better? If so, what's a good way of implementing this. I was thinking of doing this: In the API, I would have two functions for each action: // Here, "Credential" objects are just something I made up public void AddCustomer(string customerName, Credential credential , bool checkSecurity) { if(checkSecurity) { if(Has_Rights_To_Add_Customer(credential)) // made up for clarity { AddCustomer(customerName); } else // throw an exception or somehow present an error } else AddCustomer(customerName); } public void AddCustomer(string customerName) { // actual logic to add the customer into the DB or whatever // Would it be good for this method to verify that the caller is the Web App // through some method? } So, is this a good design or should I do something differently? My next question is that clearly it doesn't seem like I can really use [Authorize ...] for determining if a user has the permissions to do something. In fact, one action might depend on a variety of permissions and the View might hide or show certain options depending on the permission. What's the best way to do this? Should I have some kind of PermissionSet object that the user carries around throughout the Web App in Session or whatever and the MVC Action method would check if that user can use that Action and then the View will have some ViewData or whatever where it checks the various permissions to do Hide/Show?

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Java multiple class compositing and boiler plate reduction

- by h2g2java

We all know why Java does/should not have multiple inheritance. So this is not questioning about what has already been debated till-cows-come-home. This discusses what we would do when we wish to create a class that has the characteristics of two or more other classes. Probably, most of us would do this to "inherit" from three classes. For simplicity, I left out the constructor.: class Car extends Vehicle { final public Transport transport; final public Machine machine; } So that, Car class directly inherits methods and objects of Vehicle class, but would have to refer to transport and machine explicitly to refer to objects instantiated in Transport and Machine. Car car = new Car(); car.drive(); // from Vehicle car.transport.isAmphibious(); // from Transport car.machine.getCO2Footprint(); // from Machine I thought this was a good idea until when I encounter frameworks that require setter and getter methods. For example, the XML <Car amphibious='false' footPrint='1000' model='Fordstatic999'/> would look for the methods setAmphibious(..), setFootPrint(..) and setModel(..). Therefore, I have to project the methods from Transport and Machine classes class Car extends Vehicle { final public Transport transport; final public Machine machine; public void setAmphibious(boolean b){ this.transport.setAmphibious(b); } public void setFootPrint(String fp){ this.machine.setFootPrint(fp); } } This is OK, if there were just a few characteristics. Right now, I am trying to adapt all of SmartGWT into GWT UIBinder, especially those classes that are not a GWT widget. There are lots of characteristics to project. Wouldn't it be nice if there exists some form of annotation framework that is like this: class Car extends Vehicle @projects {Transport @projects{Machine @projects Guzzler}} { /* No need to explicitly instantiate Transport, Machine or Guzzler */ .... } Where, in case of common names of characteristics exist, the characteristics of Machine would take precedence Guzzler's, and Transport's would have precedence over Machine's, and Vehicle's would have precedence over Transport's. The annotation framework would then instantiate Transport, Machine and Guzzler as hidden members of Car and expand to break-out the protected/public characteristics, in the precedence dictated by the @project annotation sequence, into actual source code or into byte-code. Preferably into byte-code. So that the setFootPrint method is found in both Machine and Guzzler, only that of Machine's would be projected. Questions: Don't you think this is a good idea to have such a framework? Does such a framework already exist? Tell me where/what. Is there an eclipse plugin that does it? Is there a proposal or plan anywhere that you know about such an annotation framework? It would be wonderful too, if the annotation/plugin framework lets me specify that boolean, int, or whatever else needs to be converted from String and does the conversion/parsing for me too. Please advise, somebody. I hope wording of my question was clear enough. Thx. Edited: To avoid OO enthusiasts jumping to conclusion, I have renamed the title of this question.

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Isn't it better to use a single try catch instead of tons of TryParsing and other error handling sometimes?

- by Ryan Peschel

I know people say it's bad to use exceptions for flow control and to only use exceptions for exceptional situations, but sometimes isn't it just cleaner and more elegant to wrap the entire block in a try-catch? For example, let's say I have a dialog window with a TextBox where the user can type input in to be parsed in a key-value sort of manner. This situation is not as contrived as you might think because I've inherited code that has to handle this exact situation (albeit not with farm animals). Consider this wall of code: class Animals { public int catA, catB; public float dogA, dogB; public int mouseA, mouseB, mouseC; public double cow; } class Program { static void Main(string[] args) { string input = "Sets all the farm animals CAT 3 5 DOG 21.3 5.23 MOUSE 1 0 1 COW 12.25"; string[] splitInput = input.Split(' '); string[] animals = { "CAT", "DOG", "MOUSE", "COW", "CHICKEN", "GOOSE", "HEN", "BUNNY" }; Animals animal = new Animals(); for (int i = 0; i < splitInput.Length; i++) { string token = splitInput[i]; if (animals.Contains(token)) { switch (token) { case "CAT": animal.catA = int.Parse(splitInput[i + 1]); animal.catB = int.Parse(splitInput[i + 2]); break; case "DOG": animal.dogA = float.Parse(splitInput[i + 1]); animal.dogB = float.Parse(splitInput[i + 2]); break; case "MOUSE": animal.mouseA = int.Parse(splitInput[i + 1]); animal.mouseB = int.Parse(splitInput[i + 2]); animal.mouseC = int.Parse(splitInput[i + 3]); break; case "COW": animal.cow = double.Parse(splitInput[i + 1]); break; } } } } } In actuality there are a lot more farm animals and more handling than that. A lot of things can go wrong though. The user could enter in the wrong number of parameters. The user can enter the input in an incorrect format. The user could specify numbers too large or too small for the data type to handle. All these different errors could be handled without exceptions through the use of TryParse, checking how many parameters the user tried to use for a specific animal, checking if the parameter is too large or too small for the data type (because TryParse just returns 0), but every one should result in the same thing: A MessageBox appearing telling the user that the inputted data is invalid and to fix it. My boss doesn't want different message boxes for different errors. So instead of doing all that, why not just wrap the block in a try-catch and in the catch statement just display that error message box and let the user try again? Maybe this isn't the best example but think of any other scenario where there would otherwise be tons of error handling that could be substituted for a single try-catch. Is that not the better solution?

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Need help with a possible memory management problem(leak) regarding NSMutableArray

- by user309030

Hi, I'm a beginner level programmer trying to make a game app for the iphone and I've encountered a possible issue with the memory management (exc_bad_access) of my program so far. I've searched and read dozens of articles regarding memory management (including apple's docs) but I still can't figure out what exactly is wrong with my codes. So I would really appreciate it if someone can help clear up the mess I made for myself. - (void)viewDidLoad { [super viewDidLoad]; self.gameState = gameStatePaused; fencePoleArray = [[NSMutableArray alloc] init]; fencePoleImageArray = [[NSMutableArray alloc] init]; fenceImageArray = [[NSMutableArray alloc] init]; mainField = CGRectMake(10, 35, 310, 340); .......... [NSTimer scheduledTimerWithTimeInterval:0.05 target:self selector:@selector(gameLoop) userInfo:nil repeats:YES]; } So basically, the player touches the screen to set up the fences/poles -(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { if(.......) { ....... } else { UITouch *touch = [[event allTouches] anyObject]; currentTapLoc = [touch locationInView:touch.view]; NSLog(@"%i, %i", (int)currentTapLoc.x, (int)currentTapLoc.y); if(CGRectContainsPoint(mainField, currentTapLoc)) { if([self checkFence]) { onFencePole++; //this 3 set functions adds their respective objects into the 3 NSMutableArrays using addObject: [self setFencePole]; [self setFenceImage]; [self setFencePoleImage]; ....... } } else { ....... } } } } The setFence function (setFenceImage and setFencePoleImage is similar to this) -(void)setFencePole { Fence *fencePole; if (!elecFence) { fencePole = [[Fence alloc] initFence:onFencePole fenceType:1 fencePos:currentTapLoc]; } else { fencePole = [[Fence alloc] initFence:onFencePole fenceType:2 fencePos:currentTapLoc]; } [fencePoleArray addObject:fencePole]; [fencePole release]; and whenever I press a button in the game, endOpenState is called to clear away all the extra images(fence/poles) on the screen and also to remove all existing objects in the 3 NSMutableArray -(void)endOpenState { ........ int xMax = [fencePoleArray count]; int yMax = [fenceImageArray count]; for (int x = 0; x < xMax; x++) { [[fencePoleImageArray objectAtIndex:x] removeFromSuperview]; } for (int y = 0; y < yMax; y++) { [[fenceImageArray objectAtIndex:y] removeFromSuperview]; } [fencePoleArray removeAllObjects]; [fencePoleImageArray removeAllObjects]; [fenceImageArray removeAllObjects]; ........ } The crash happens here at the checkFence function. -(BOOL)checkFence { if (onFencePole == 0) { return YES; } else if (onFencePole >= 1 && onFencePole < currentMaxFencePole - 1) { CGPoint tempPoint1 = currentTapLoc; CGPoint tempPoint2 = [[fencePoleArray objectAtIndex:onFencePole-1] returnPos]; // the crash happens at this line if ([self checkDistance:tempPoint1 point2:tempPoint2]) { return YES; } else { return NO; } } else if (onFencePole == currentMaxFencePole - 1) { ...... } else { return NO; } } What I'm thinking of is that fencePoleArray got messed up when I used [fencePoleArray removeAllObjects] because it doesn't crash when I comment it out. It would really be great if someone can explain to me what went wrong. And thanks in advance.

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"Attach or Add an entity that is not new...loaded from another DataContext. This is not supported."

- by sah302

Similar error as other questions, but not quite the same, I am not trying to attach anything. What I am trying to do is insert a new row into a linking table, specifically UserAccomplishment. Relations are set in LINQ to User and Accomplishment Tables. I have a generic insert function: Public Function insertRow(ByVal entity As ImplementationType) As Boolean If entity IsNot Nothing Then Dim lcfdatacontext As New LCFDataContext() Try lcfdatacontext.GetTable(Of ImplementationType)().InsertOnSubmit(entity) lcfdatacontext.SubmitChanges() lcfdatacontext.Dispose() Return True Catch ex As Exception Return False End Try Else Return False End If End Function If you try and give UserAccomplishment the two appropriate objects this will naturally crap out if either the User or Accomplishment already exist. It only works when both user and accomplishment don't exist. I expected this behavior. What does work is simply giving the userAccomplishment object a user.id and accomplishment.id and populating the rest of the fields. This works but is kind of awkward to use in my app, it would be much easier to simply pass in both objects and have it work out what already exists and what doesn't. Okay so I made the following (please ignore the fact that this is horribly inefficient because I know it is): Public Class UserAccomplishmentDao Inherits EntityDao(Of UserAccomplishment) Public Function insertLinkerObjectRow(ByVal userAccomplishment As UserAccomplishment) Dim insertSuccess As Boolean = False If Not userAccomplishment Is Nothing Then Dim userDao As New UserDao() Dim accomplishmentDao As New AccomplishmentDao() Dim user As New User() Dim accomplishment As New Accomplishment() 'see if either object already exists in db' user = userDao.getOneByValueOfProperty("Id", userAccomplishment.User.Id) accomplishment = accomplishmentDao.getOneByValueOfProperty("Id", userAccomplishment.Accomplishment.Id) If user Is Nothing And accomplishment Is Nothing Then 'neither the user or the accomplishment exist, both are new so insert them both, typical insert' insertSuccess = Me.insertRow(userAccomplishment) ElseIf user Is Nothing And Not accomplishment Is Nothing Then 'user is new, accomplishment is not new, so just insert the user, and the relation in userAccomplishment' Dim userWithExistingAccomplishment As New UserAccomplishment(userAccomplishment.User, userAccomplishment.Accomplishment.Id, userAccomplishment.LastUpdatedBy) insertSuccess = Me.insertRow(userWithExistingAccomplishment) ElseIf Not user Is Nothing And accomplishment Is Nothing Then 'user is not new, accomplishment is new, so just insert the accomplishment, and the relation in userAccomplishment' Dim existingUserWithAccomplishment As New UserAccomplishment(userAccomplishment.UserId, userAccomplishment.Accomplishment, userAccomplishment.LastUpdatedBy) insertSuccess = Me.insertRow(existingUserWithAccomplishment) Else 'both are not new, just add the relation' Dim userAccomplishmentBothExist As New UserAccomplishment(userAccomplishment.User.Id, userAccomplishment.Accomplishment.Id, userAccomplishment.LastUpdatedBy) insertSuccess = Me.insertRow(userAccomplishmentBothExist) End If End If Return insertSuccess End Function End Class Alright, here I basically check if the supplied user and accomplishment already exists in the db, and if so call an appropriate constructor that will leave whatever already exists empty, but supply the rest of the information so the insert can succeed. However, upon trying an insert: Dim result As Boolean = Me.userAccomplishmentDao.insertLinkerObjectRow(userAccomplishment) In which the user already exists, but the accomplishment does not (the 99% typical scenario) I get the error: "An attempt has been made to Attach or Add an entity that is not new, perhaps having been loaded from another DataContext. This is not supported." I have debugged this multiple times now and am not sure why this is occuring, if either User or Accomplishment exist, I am not including it in the final object to try to insert. So nothing appears to be attempted to be added. Even in debug, upon insert, the object was set to empty. So the accomplishment is new and the user is empty. 1) Why is it still saying that and how can I fix it ..using my current structure 2) Pre-emptive 'use repository pattern answers' - I know this way kind of sucks in general and I should be using the repository pattern. However, I can't use that in the current project because I don't have time to refactor that due to my non existence knowledge of it and time constraints. The usage of the app is going to so small that the inefficient use of datacontext's and what have you won't matter so much. I can refactor it once it's up and running, but for now I just need to 'push through' with my current structure. Edit: I also just tested this when having both already exists, and only insert each object's IDs into the table, that works. So I guess I could manually insert whichever object doesn't exist as a single insert, then put the ids only into the linking table, but I still don't know why when one object exists, and I make it empty, it doens't work.

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Increasing speed of python code

- by Curious2learn

Hi, I have some python code that has many classes. I used cProfile to find that the total time to run the program is 68 seconds. I found that the following function in a class called Buyers takes about 60 seconds of those 68 seconds. I have to run the program about 100 times, so any increase in speed will help. Can you suggest ways to increase the speed by modifying the code? If you need more information that will help, please let me know. def qtyDemanded(self, timePd, priceVector): '''Returns quantity demanded in period timePd. In addition, also updates the list of customers and non-customers. Inputs: timePd and priceVector Output: count of people for whom priceVector[-1] < utility ''' ## Initialize count of customers to zero ## Set self.customers and self.nonCustomers to empty lists price = priceVector[-1] count = 0 self.customers = [] self.nonCustomers = [] for person in self.people: if person.utility >= price: person.customer = 1 self.customers.append(person) else: person.customer = 0 self.nonCustomers.append(person) return len(self.customers) self.people is a list of person objects. Each person has customer and utility as its attributes. EDIT - responsed added ------------------------------------- Thanks so much for the suggestions. Here is the response to some questions and suggestions people have kindly made. I have not tried them all, but will try others and write back later. (1) @amber - the function is accessed 80,000 times. (2) @gnibbler and others - self.people is a list of Person objects in memory. Not connected to a database. (3) @Hugh Bothwell cumtime taken by the original function - 60.8 s (accessed 80000 times) cumtime taken by the new function with local function aliases as suggested - 56.4 s (accessed 80000 times) (4) @rotoglup and @Martin Thomas I have not tried your solutions yet. I need to check the rest of the code to see the places where I use self.customers before I can make the change of not appending the customers to self.customers list. But I will try this and write back. (5) @TryPyPy - thanks for your kind offer to check the code. Let me first read a little on the suggestions you have made to see if those will be feasible to use. EDIT 2 Some suggested that since I am flagging the customers and noncustomers in the self.people, I should try without creating separate lists of self.customers and self.noncustomers using append. Instead, I should loop over the self.people to find the number of customers. I tried the following code and timed both functions below f_w_append and f_wo_append. I did find that the latter takes less time, but it is still 96% of the time taken by the former. That is, it is a very small increase in the speed. @TryPyPy - The following piece of code is complete enough to check the bottleneck function, in case your offer is still there to check it with other compilers. Thanks again to everyone who replied. import numpy class person(object): def __init__(self, util): self.utility = util self.customer = 0 class population(object): def __init__(self, numpeople): self.people = [] self.cus = [] self.noncus = [] numpy.random.seed(1) utils = numpy.random.uniform(0, 300, numpeople) for u in utils: per = person(u) self.people.append(per) popn = population(300) def f_w_append(): '''Function with append''' P = 75 cus = [] noncus = [] for per in popn.people: if per.utility >= P: per.customer = 1 cus.append(per) else: per.customer = 0 noncus.append(per) return len(cus) def f_wo_append(): '''Function without append''' P = 75 for per in popn.people: if per.utility >= P: per.customer = 1 else: per.customer = 0 numcustomers = 0 for per in popn.people: if per.customer == 1: numcustomers += 1 return numcustomers

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Best way to get back to using the power of lxml after having to use a regex to find something in an

- by PyNEwbie

I am trying to rip some text out of a large number of html documents (numbers in the hundreds of thousands). The documents are really forms but they are prepared by a very large group of different organizations so there is significant variation in how they create the document. For example, the documents are divided into chapters. I might want to extract the contents of Chapter 5 from every document so I can analyze the content of the chapter. Initially I thought this would be easy but it turns out that the authors might use a set of non-nested tables throughout the document to hold the content so that Chapter n could be displayed using td tags inside a table. Or they might use other elements such as p tags H tags, div tags or any other block level element. After trying repeatedly to use lxml to help me identify the beginning and end of each chapter I have determined that it is a lot cleaner to use a regular expression because in every case, no matter what the enclosing html element is the chapter label is always in the form of >Chapter # It is a little more complicated in that there might be some white space or non-breaking space represented in different ways ( or or just spaces). Nonetheless it was trivial to write a regular expression to identify the beginning of each section. (The beginning of one section is the end of the previous section.) But now I want to use lxml to get the text out. My thought is that I have really no choice but to walk along my string to find the close tag for the element that encloses the text I am using to find the relevant section. That is here is one example where the element holding the Chapter name is a div <div style="DISPLAY: block; MARGIN-LEFT: 0pt; TEXT-INDENT: 0pt; MARGIN-RIGHT: 0pt" align="left"><font style="DISPLAY: inline; FONT-WEIGHT: bold; FONT-SIZE: 10pt; FONT-FAMILY: Times New Roman">Chapter 1.   Our Beginnings.</font></div> So I am imagining that I would begin at the location where I found the match for chapter 1 and set up a regular expressions to find the next </div|</td|</p|</h1 . . . So at this point I have identified the type of element holding my chapter heading I can use the same logic to find all of the text that is within that element that is set up a regular expression to help me mark from >Chapter 1.   Our Beginnings.< So I have identified where my Chapter 1 begins I can do the same for chapter 2 (which is where Chapter 1 ends) Now I am imagining that I am going to snip the document beginning at the opening of the element that I identified as the element the indicates where chapter 1 begins and ending just before the opening of the element that I identified as the element that indicates where Chapter 2 begins. The string that I have identified will then be fed to lxml to use its power to get the content. I am going to all of this trouble because I have read over and over - never use a regular expression to extract content from html documents and I have not hit on a way to be as accurate with lxml to identify the starting and ending locations for the text I want to extract. For example, I can never be certain that the subtitle of Chapter 1 is Our Beginnings it could be Our Red Canary. Let me say that I spent two solid days trying with lxml to be confident that I had the beginning and ending elements and I could only be accurate <60% of the time but a very short regular expression has given me better than 95% success. I have a tendency to make things more complicated than necessary so I am wondering if anyone has seen or solved a similar problems and if they had an approach (not the details mind you) that they would like to offer.

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Hibernate many-to-many mapping not saved in pivot table

- by vincent

I having problems saving many to many relationships to a pivot table. The way the pojos are created is unfortunately a pretty long process which spans over a couple of different threads which work on the (to this point un-saved) object until it is finally persisted. I associate the related objects to one another right after they are created and when debugging I can see the List of related object populated with their respective objects. So basically all is fine to this point. When I persist the object everything get saved except the relations in the pivot table. mapping files: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.thebeansgroup.jwinston.plugin.orm.hibernate.object"> <class name="ShowObject" table="show_object"> <id name="id"> <generator class="native" /> </id> <property name="name" /> <set cascade="all" inverse="true" name="venues" table="venue_show"> <key column="show_id"/> <many-to-many class="VenueObject"/> </set> </class> </hibernate-mapping> and the other <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping package="com.thebeansgroup.jwinston.plugin.orm.hibernate.object"> <class name="VenueObject" table="venue_object"> <id name="id"> <generator class="native"/> </id> <property name="name"/> <property name="latitude" type="integer"/> <property name="longitude" type="integer"/> <set cascade="all" inverse="true" name="shows" table="venue_show"> <key column="venue_id"/> <many-to-many class="ShowObject"/> </set> </class> </hibernate-mapping> pojos: public class ShowObject extends OrmObject { private Long id; private String name; private Set venues; public ShowObject() { } public Long getId() { return id; } public void setId(Long id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Set getVenues() { return venues; } public void setVenues(Set venues) { this.venues = venues; } } and the other: public class VenueObject extends OrmObject { private Long id; private String name; private int latitude; private int longitude; private Set shows = new HashSet(); public VenueObject() { } @Id @GeneratedValue(strategy = GenerationType.AUTO) public Long getId() { return id; } public void setId(Long id) { this.id = id; } public int getLatitude() { return latitude; } public void setLatitude(int latitude) { this.latitude = latitude; } public int getLongitude() { return longitude; } public void setLongitude(int longitude) { this.longitude = longitude; } public String getName() { return name; } public void setName(String name) { this.name = name; } public Set getShows() { return shows; } public void setShows(Set shows) { this.shows = shows; } } Might the problem be related to the lack of annotations?

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