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• Consolidating coding styles: Funcs, private method, single method classes

  - by jdoig

  Hi all, We currently have 3 devs with, some, conflicting styles and I'm looking for a way to bring peace to the kingdom... The Coders: Foo 1: Likes to use Func's & Action's inside public methods. He uses actions to alias off lengthy method calls and Func's to perform simple tasks that can be expressed in 1 or 2 lines and will be used frequently through out the code Pros: The main body of his code is succinct and very readable, often with only one or 2 public methods per class and rarely any private methods. Cons: The start of methods contain blocks of lambda rich code that other developers don't enjoy reading; and, on occasion, can contain higher order functions that other dev's REALLY don't like reading. Foo 2: Likes to create a private method for (almost) everything the public method will have to do . Pros: Public methods remain small and readable (to all developers). Cons: Private methods are numerous. With private methods that call into other private methods, that call into... etc, etc. Making code hard to navigate. Foo 3: Likes to create a public class with a, single, public method for every, non-trivial, task that needs performing, then dependency inject them into other objects. Pros: Easily testable, easy to understand (one object, one responsibility). Cons: project gets littered by classes, opening multiple class files to understand what code does makes navigation awkward. It would be great to take the best of all these techniques... Foo-1 Has really nice, readable (almost dsl-like) code... for the most part, except for all the Action and Func lambda shenanigans bulked together at the start of a method. Foo-3 Has highly testable and extensible code that just feels a bit "belt-&-braces" for some solutions and has some code-navigation niggles (constantly hitting F12 in VS and opening 5 other .cs files to find out what a single method does). And Foo-2... Well I'm not sure I like anything about the one-huge .cs file with 2 public methods and 12 private ones, except for the fact it's easier for juniors to dig into. I admit I grossly over-simplified the explanations of those coding styles; but if any one knows of any patterns, practices or diplomatic-manoeuvres that can help unite our three developers (without just telling any of them to just "stop it!") that would be great. From a feasibility standpoint : Foo-1's style meets with the most resistance due to some developers finding lambda and/or Func's hard to read. Foo-2's style meets with a less resistance as it's just so easy to fall into. Foo-3's style requires the most forward thinking and is difficult to enforce when time is short. Any ideas on some coding styles or conventions that can make this work?

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• C program using inotify to monitor multiple directories along with sub-directories?

  - by lakshmipathi

  I have program which monitors a directory (/test) and notify me. I want to improve this to monitor another directory (say /opt). And also how to monitor it's subdirectories , current i'll get notified if any changes made to files under /test . but i'm not getting any inotifcation if changes made sub-directory of /test, that is touch /test/sub-dir/files.txt .. Here my current code - hope this will help /* Simple example for inotify in Linux. inotify has 3 main functions. inotify_init1 to initialize inotify_add_watch to add monitor then inotify_??_watch to rm monitor.you the what to replace with ??. yes third one is inotify_rm_watch() */ #include <sys/inotify.h> int main(){ int fd,wd,wd1,i=0,len=0; char pathname[100],buf[1024]; struct inotify_event *event; fd=inotify_init1(IN_NONBLOCK); /* watch /test directory for any activity and report it back to me */ wd=inotify_add_watch(fd,"/test",IN_ALL_EVENTS); while(1){ //read 1024 bytes of events from fd into buf i=0; len=read(fd,buf,1024); while(i<len){ event=(struct inotify_event *) &buf[i]; /* check for changes */ if(event->mask & IN_OPEN) printf("%s :was opened\n",event->name); if(event->mask & IN_MODIFY) printf("%s : modified\n",event->name); if(event->mask & IN_ATTRIB) printf("%s :meta data changed\n",event->name); if(event->mask & IN_ACCESS) printf("%s :was read\n",event->name); if(event->mask & IN_CLOSE_WRITE) printf("%s :file opened for writing was closed\n",event->name); if(event->mask & IN_CLOSE_NOWRITE) printf("%s :file opened not for writing was closed\n",event->name); if(event->mask & IN_DELETE_SELF) printf("%s :deleted\n",event->name); if(event->mask & IN_DELETE) printf("%s :deleted\n",event->name); /* update index to start of next event */ i+=sizeof(struct inotify_event)+event->len; } } }

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• How to properly downcast in C# with a SWIG generated interface?

  - by JG

  I've got a very large and mature C++ code base that I'm trying to use SWIG on to generate a C# interface for. I cannot change the actual C++ code itself but we can use whatever SWIG offers in the way of extending/updating it. I'm facing an issue where a function C++ is written as such: A* SomeClass::next(A*) The caller might do something like: A* acurr = 0; while( (acurr = sc->next(acurr)) != 0 ){ if( acurr isoftype B ){ B* b = (B*)a; ...do some stuff with b.. } elseif( acurr isoftype C ) ... } Essentially, iterating through a container elements that depending on their true type, do something different. The SWIG generated C# layer for the "next" function unfortunately does the following: return new A(); So the calling code in C# land cannot determine if the returned object is actually a derived class or not, it actually appears to always be the base class (which does make sense). I've come across several solutions: Use the %extend SWIG keyword to add a method on an object and ultimately call dynamic_cast. The downside to this approach, as I see it, is that this requires you to know the inheritance hierarchy. In my case it is rather huge and I see this is as a maintenance issue. Use the %factory keyword to supply the method and the derived types and have SWIG automatically generate the dynamic_cast code. This appears to be a better solution that the first, however upon a deeper look it still requires you to hunt down all the methods and all the possible derived types it could return. Again, a huge maintenance issue. I wish I had a doc link for this but I can't find one. I found out about this functionality by looking through the example code that comes with SWIG. Create a C# method to create an instance of the derived object and transfer the cPtr to the new instance. While I consider this clumsy, it does work. See an example below. public static object castTo(object fromObj, Type toType) { object retval = null; BaseClass fromObj2 = fromObj as BaseClass; HandleRef hr = BaseClass.getCPtr(fromObj2); IntPtr cPtr = hr.Handle; object toObj = Activator.CreateInstance(toType, cPtr, false); // make sure it actually is what we think it is if (fromObj.GetType().IsInstanceOfType(toObj)) { return toObj; } return retval; } Are these really the options? And if I'm not willing to dig through all the existing functions and class derivations, then I'm left with #3? Any help would be appreciated.

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• How do I get the next token in a Cstring if I want to use it as an int? (c++)

  - by Van

  My objective is to take directions from a user and eventually a text file to move a robot. The catch is that I must use Cstrings(such as char word[];) rather than the std::string and tokenize them for use. the code looks like this: void Navigator::manualDrive() { char uinput[1]; char delim[] = " "; char *token; cout << "Enter your directions below: \n"; cin.ignore(); cin.getline (uinput, 256); token=strtok(uinput, delim); if(token == "forward") { int inches; inches=token+1; travel(inches); } } I've never used Cstrings I've never tokenized anything before, and I don't know how to write this. Our T.A.'s expect us to google and find all the answers because they are aware we've never been taught these methods. Everyone in my lab is having much more trouble than usual. I don't know the code to write but I know what I want my program to do. I want it to execute like this: 1) Ask for directions. 2) cin.getline the users input 3) tokenize the inputed string 4) if the first word token == "forward" move to the next token and find out how many inches to move forward then move forward 5) else if the first token == "turn" move to the next token. if the next token == "left" move to the next token and find out how many degrees to turn left I will have to do this for forward x, backward x, turn left x, turn right x, and stop(where x is in inches or degrees). I already wrote functions that tell the robot how to move forward an inch and turn in degrees. I just need to know how to convert the inputted strings to all lowercase letters and move from token to token and convert or extract the numbers from the string to use them as integers. If all is not clear you can read my lab write up at this link: http://www.cs.utk.edu/~cs102/robot_labs/Lab9.html If anything is unclear please let me know, and I will clarify as best I can.

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• Seeking STL-aware c++filt

  - by Don Wakefield

  In my development environment, I'm compiling a code base using GNU C++ 3.4.6. Code is under development, and unfortunately crashes now and then. It's nice to be able to run the traceback through a demangler, and I use c++filt 3.4. The problem comes when functions have a number of STL parameters. Consider My_callback::operator()( Status&, std::set<std::string> const&, std::vector<My_parameter*> const&, My_attribute_set const&, std::vector<My_parameter_base*> const&, std::vector<My_parameter> const&, std::set<std::string> const& ) { // ... } When this function is in the traceback, the mangled output on my platform is: (_ZN30My_callbackclER11StatusRKSt3setISsSt4lessISsESaISsEERKSt6vectorIP13My_parameterSaISB_EERK17My_attribute_setRKS9_IP18My_parameter_baseSaISK_EERKS9_ISA_SaISA_EES8_+0x76a) [0x13ffdaa] c++filt kindly demangles it to (My_callback::operator()(Status&, std::set<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&, std::vector<My_parameter*, std::allocator<My_parameter*> > const&, My_attribute_set const&, std::vector<My_parameter_base*, std::allocator<My_parameter_base*> > const&, std::vector<My_parameter, std::allocator<My_parameter> > const&, std::set<std::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::less<std::basic_string<char, std::char_traits<char>, std::allocator<char> > >, std::allocator<std::basic_string<char, std::char_traits<char>, std::allocator<char> > > > const&)+0x76a) [0x13ffdaa] This is the same problem as compiler errors encountered when using templates. However, the STL is a fairly regular and recognizable package of templates. So what I'm hoping is that someone out there has created an enhanced version of c++filt which would dump something closer to the original function signature. Any hints?

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• Abstract Data Type: Any1 can help me this? thanks..

  - by Aga Hibaya

  Objectives: Implement the Abstract Data Type (ADT) List using dynamically allocated arrays and structures. Description A LIST is an ordered collection of items where items may be inserted anywhere in the list. Implement a LIST using an array as follows: struct list { int *items; // pointer to the array int size; // actual size of the array int count; // number of items in the array }; typedef struct list *List; // pointer to the structure Implement the following functions: a) List newList(int size); - will create a new List and return its pointer. Allocate space for the structure, allocate space for the array, then initialize size and count, return the pointer. b) void isEmpty(List list); c) void display(List list); d) int contains(List list, int item); e) void remove(List list, int i) ; f) void insertAfter(List list,int item, int i); g) void addEnd(List list,int item) - add item at the end of the list – simply store the data at position count, then increment count. If the array is full, allocate an array twice as big as the original. count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 addEnd(list,40) will result to count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 40 h) void addFront(List list,int item) - shift all elements to the right so that the item can be placed at position 0, then increment count. Bonus: if the array is full, allocate an array twice as big as the original. count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 addFront(list,40) will result to count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 10 15 20 30 i) void removeFront(List list) - shift all elements to the left and decrement count; count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 10 15 20 30 removeFront(list) will result to count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 5 10 15 20 30 j) void remove(List list,int item) - get the index of the item in the list and then shift all elements to the count = 6 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 10 15 20 30 remove(list,10) will result to count = 5 size = 10 0 1 2 3 4 5 6 7 8 9 40 5 15 20 30 Remarks

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• Good style for handling constructor failure of critical object

  - by mtlphil

  I'm trying to decide between two ways of instantiating an object & handling any constructor exceptions for an object that is critical to my program, i.e. if construction fails the program can't continue. I have a class SimpleMIDIOut that wraps basic Win32 MIDI functions. It will open a MIDI device in the constructor and close it in the destructor. It will throw an exception inherited from std::exception in the constructor if the MIDI device cannot be opened. Which of the following ways of catching constructor exceptions for this object would be more in line with C++ best practices Method 1 - Stack allocated object, only in scope inside try block #include <iostream> #include "simplemidiout.h" int main() { try { SimpleMIDIOut myOut; //constructor will throw if MIDI device cannot be opened myOut.PlayNote(60,100); //..... //myOut goes out of scope outside this block //so basically the whole program has to be inside //this block. //On the plus side, it's on the stack so //destructor that handles object cleanup //is called automatically, more inline with RAII idiom? } catch(const std::exception& e) { std::cout << e.what() << std::endl; std::cin.ignore(); return 1; } std::cin.ignore(); return 0; } Method 2 - Pointer to object, heap allocated, nicer structured code? #include <iostream> #include "simplemidiout.h" int main() { SimpleMIDIOut *myOut; try { myOut = new SimpleMIDIOut(); } catch(const std::exception& e) { std::cout << e.what() << std::endl; delete myOut; return 1; } myOut->PlayNote(60,100); std::cin.ignore(); delete myOut; return 0; } I like the look of the code in Method 2 better, don't have to jam my whole program into a try block, but Method 1 creates the object on the stack so C++ manages the object's life time, which is more in tune with RAII philosophy isn't it? I'm still a novice at this so any feedback on the above is much appreciated. If there's an even better way to check for/handle constructor failure in a siatuation like this please let me know.

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• Best method for converting several sets of numbers with several different ratios

  - by C Patton

  I'm working on an open-source harm reduction application for opioid addicts. One of the features in this application is the conversion (in mg/mcg) between common opioids, so people don't overdose by accident. If you're morally against opioid addiction and wouldn't respond because of your morals, please consider that this application is for HARM REDUCTION.. So people don't end up dead. I have this data.. 3mg morphine IV = 10mcg fentanyl IV 2mg morphine oral = 1mg oxycodone oral 3mg oral morphine = 1mg oxymorphone oral 7.0mg morphine oral = 1mg hydromorphone oral 1mg morphine iv = .10mg oxymorphone iv 1mg morphine oral = 1mg hydrocodone oral 1mg morphine oral = 6.67mg codeine oral 1mg morphine oral = .10mg methadone oral And I have a textbox that is the source dosage in mg (a double) that the user can enter in. Underneath this, I have radio boxes for the source substance (ie: morphine) and the destination substance (ie oxycodone) for conversion.. I've been trying to think of the most efficient way to do this, but nearly every seems sloppy. If I were to do something like public static double MorphinetoOxycodone(string morphineValue) { double morphine = Double.Parse(morphineValue); return (morphine / 2 ); } I would also have to make a function for OxycodonetoMorphine, OxycodonetoCodeine, etc.. and then would end up with dozens functions.. There must be an easier way than this that I'm missing. If you'll notice, all of my conversions use morphine as the base value.. what might be the easiest way to use the morphine value to convert one opioid to another? For example, if 1mg morphine oral is equal to 1mg hydrocodone and 1mg morphine oral is equal to .10mg methadone, wouldn't I just multiply 1*.10 to get the hydrocodone-methadone value? Implementing this idea is what I'm having the most trouble with. Any help would be GREATLY appreciated.. and if you'd like, I would add your name/nickname to the credits in this program. It's possible that many, many people around the world will use this (I'm translating it into several languages as well) and to know that your work could've helped an addict from dying.. I think that's a great thing :) -cory

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• How do I recover from an unchecked exception?

  - by erickson

  Unchecked exceptions are alright if you want to handle every failure the same way, for example by logging it and skipping to the next request, displaying a message to the user and handling the next event, etc. If this is my use case, all I have to do is catch some general exception type at a high level in my system, and handle everything the same way. But I want to recover from specific problems, and I'm not sure the best way to approach it with unchecked exceptions. Here is a concrete example. Suppose I have a web application, built using Struts2 and Hibernate. If an exception bubbles up to my "action", I log it, and display a pretty apology to the user. But one of the functions of my web application is creating new user accounts, that require a unique user name. If a user picks a name that already exists, Hibernate throws an org.hibernate.exception.ConstraintViolationException (an unchecked exception) down in the guts of my system. I'd really like to recover from this particular problem by asking the user to choose another user name, rather than giving them the same "we logged your problem but for now you're hosed" message. Here are a few points to consider: There a lot of people creating accounts simultaneously. I don't want to lock the whole user table between a "SELECT" to see if the name exists and an "INSERT" if it doesn't. In the case of relational databases, there might be some tricks to work around this, but what I'm really interested in is the general case where pre-checking for an exception won't work because of a fundamental race condition. Same thing could apply to looking for a file on the file system, etc. Given my CTO's propensity for drive-by management induced by reading technology columns in "Inc.", I need a layer of indirection around the persistence mechanism so that I can throw out Hibernate and use Kodo, or whatever, without changing anything except the lowest layer of persistence code. As a matter of fact, there are several such layers of abstraction in my system. How can I prevent them from leaking in spite of unchecked exceptions? One of the declaimed weaknesses of checked exceptions is having to "handle" them in every call on the stack—either by declaring that a calling method throws them, or by catching them and handling them. Handling them often means wrapping them in another checked exception of a type appropriate to the level of abstraction. So, for example, in checked-exception land, a file-system–based implementation of my UserRegistry might catch IOException, while a database implementation would catch SQLException, but both would throw a UserNotFoundException that hides the underlying implementation. How do I take advantage of unchecked exceptions, sparing myself of the burden of this wrapping at each layer, without leaking implementation details?

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• How does Sentry aggregate errors?

  - by Hugo Rodger-Brown

  I am using Sentry (in a django project), and I'd like to know how I can get the errors to aggregate properly. I am logging certain user actions as errors, so there is no underlying system exception, and am using the culprit attribute to set a friendly error name. The message is templated, and contains a common message ("User 'x' was unable to perform action because 'y'"), but is never exactly the same (different users, different conditions). Sentry clearly uses some set of attributes under the hood to determine whether to aggregate errors as the same exception, but despite having looked through the code, I can't work out how. Can anyone short-cut my having to dig further into the code and tell me what properties I need to set in order to manage aggregation as I would like? [UPDATE 1: event grouping] This line appears in sentry.models.Group: class Group(MessageBase): """ Aggregated message which summarizes a set of Events. """ ... class Meta: unique_together = (('project', 'logger', 'culprit', 'checksum'),) ... Which makes sense - project, logger and culprit I am setting at the moment - the problem is checksum. I will investigate further, however 'checksum' suggests that binary equivalence, which is never going to work - it must be possible to group instances of the same exception, with differenct attributes? [UPDATE 2: event checksums] The event checksum comes from the sentry.manager.get_checksum_from_event method: def get_checksum_from_event(event): for interface in event.interfaces.itervalues(): result = interface.get_hash() if result: hash = hashlib.md5() for r in result: hash.update(to_string(r)) return hash.hexdigest() return hashlib.md5(to_string(event.message)).hexdigest() Next stop - where do the event interfaces come from? [UPDATE 3: event interfaces] I have worked out that interfaces refer to the standard mechanism for describing data passed into sentry events, and that I am using the standard sentry.interfaces.Message and sentry.interfaces.User interfaces. Both of these will contain different data depending on the exception instance - and so a checksum will never match. Is there any way that I can exclude these from the checksum calculation? (Or at least the User interface value, as that has to be different - the Message interface value I could standardise.) [UPDATE 4: solution] Here are the two get_hash functions for the Message and User interfaces respectively: # sentry.interfaces.Message def get_hash(self): return [self.message] # sentry.interfaces.User def get_hash(self): return [] Looking at these two, only the Message.get_hash interface will return a value that is picked up by the get_checksum_for_event method, and so this is the one that will be returned (hashed etc.) The net effect of this is that the the checksum is evaluated on the message alone - which in theory means that I can standardise the message and keep the user definition unique. I've answered my own question here, but hopefully my investigation is of use to others having the same problem. (As an aside, I've also submitted a pull request against the Sentry documentation as part of this ;-)) (Note to anyone using / extending Sentry with custom interfaces - if you want to avoid your interface being use to group exceptions, return an empty list.)

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• Rails 3: How do I call a javascript function from a js.erb file

  - by user321775

  Now that I've upgraded to Rails 3, I'm trying to figure out the proper way to separate and reuse pieces of javascript. Here's the scenario I'm dealing with: I have a page with two areas: one with elements that should be draggable, the other with droppables. When the page loads I use jQuery to setup the draggables and droppables. Currently I have the script in the head portion of application.html.erb, which I'm sure is not the right solution but at least works. When I press a button on the page, an ajax call is made to my controller that replaces the draggables with a new set of elements that should also be draggable. I have a js.erb file that renders a partial in the correct location. After rendering I need to make the new elements draggable, so I'd like to reuse the code that currently lives in application.html.erb, but I haven't found the right way to do it. I can only make the new elements draggable by pasting the code directly into my js.erb file (yuck). What I'd like to have: - a javascript file that contains the functions prepdraggables() and prepdroppables() - a way to call either function from application.html.erb or from a js.erb file I've tried using :content_for to store and reuse the code, but can't seem to get it working correctly. What I currently have in the head section of application.html.erb <% content_for :drag_drop_prep do %> <script type="text/javascript" charset="utf-8"> $(document).ready(function () { // declare all DOM elements with class draggable to be draggable $( ".draggable" ).draggable( { revert : 'invalid' }); // declare all DOM elements with class legal to be droppable $(".legal").droppable({ hoverClass : 'legal_hover', drop : function(event, ui) { var c = new Object(); c['die'] = ui.draggable.attr("id"); c['cell'] = $(this).attr("id"); c['authenticity_token'] = encodeURIComponent(window._token); $.ajax({ type: "POST", url: "/placeDie", data: c, timeout: 5000 }); }}); }); </script> <% end %> undo.js.erb $("#board").html("<%= escape_javascript(render :partial => 'shared/board', :locals => { :playable => true, :restartable => !session[:challenge]}) %>") // This is where I want to prepare draggables. <%= javascript_include_tag "customdragdrop.js" %> // assuming this file had the draggables code from above in a prepdraggables() function prepdraggables();

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• Overwhelmed by design patterns... where to begin?

  - by Pete

  I am writing a simple prototype code to demonstrate & profile I/O schemes (HDF4, HDF5, HDF5 using parallel IO, NetCDF, etc.) for a physics code. Since focus is on IO, the rest of the program is very simple: class Grid { public: floatArray x,y,z; }; class MyModel { public: MyModel(const int &nip1, const int &njp1, const int &nkp1, const int &numProcs); Grid grid; map<string, floatArray> plasmaVariables; }; Where floatArray is a simple class that lets me define arbitrary dimensioned arrays and do mathematical operations on them (i.e. x+y is point-wise addition). Of course, I could use better encapsulation (write accessors/setters, etc.), but that's not the concept I'm struggling with. For the I/O routines, I am envisioning applying simple inheritance: Abstract I/O class defines read & write functions to fill in the "myModel" object HDF4 derived class HDF5 HDF5 using parallel IO NetCDF etc... The code should read data in any of these formats, then write out to any of these formats. In the past, I would add an AbstractIO member to myModel and create/destroy this object depending on which I/O scheme I want. In this way, I could do something like: myModelObj.ioObj->read('input.hdf') myModelObj.ioObj->write('output.hdf') I have a bit of OOP experience but very little on the Design Patterns front, so I recently acquired the Gang of Four book "Design Patterns: Elements of Reusable Object-Oriented Software". OOP designers: Which pattern(s) would you recommend I use to integrate I/O with the myModel object? I am interested in answering this for two reasons: To learn more about design patterns in general Apply what I learn to help refactor an large old crufty/legacy physics code to be more human-readable & extensible. I am leaning towards applying the Decerator pattern to myModel, so I can attach the I/O responsibilities dynamically to myModel (i.e. whether to use HDF4, HDF5, etc.). However, I don't feel very confident that this is the best pattern to apply. Reading the Gang of Four book cover-to-cover before I start coding feels like a good way to develop an unhealthy caffeine addiction. What patterns do you recommend?

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• USB windows xp final USB access issues

  - by Lex Dean

  I basically understand you C++ people, Please do not get distracted because I'm writing in Delphi. I have a stable USB Listing method that accesses all my USB devices I get the devicepath, and this structure: TSPDevInfoData = packed record Size: DWORD; ClassGuid: TGUID; DevInst: DWORD; // DEVINST handle Reserved: DWord; end; I get my ProductID and VenderID successfully from my DevicePath Lists all USB devices connected to the computer at the time That enables me to access the registry data to each device in a stable way. What I'm lacking is a little direction Is friendly name able to be written inside the connected USB Micro chips by the firmware programmer? (I'm thinking of this to identify the device even further, or is this to help identify Bulk data transfer devices like memory sticks and camera's) Can I use SPDRP_REMOVAL_POLICY_OVERRIDE to some how reset these polices What else can I do with the registry details. Identifying when some one unplugs a device The program is using (in windows XP standard) I used a documented windows event that did not respond. Can I read a registry value to identify if its still connected? using CreateFileA (DevicePath) to send and receive data I have read when some one unplugs in the middle of a data transfer its difficult clearing resources. what can IoCreateDevice do for me and how does one use it for that task This two way point of connection status and system lock up situations is very concerning. Has some one read anything about this subject recently? My objectives are to 1. list connected USB devices identify a in development Micro Controller from everything else send and receive data in a stable and fast way to the limits of the controller No lock up's transferring data Note I'm not using any service packs I understand everything USB is in ANSI when windows xp is not and .Net is all about ANSI (what a waste of memory) I plan to continue this project into a .net at a later date as an addition. MSDN gives me Structures and Functions and what should link to what ok but say little to what they get used for. What is available in my language Delphi is way over priced that it needs a major price drop.

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• How to develop a Jquery plugin to find the first child that match with a selector?

  - by Ivan

  I'm trying to make a Jquery plugin (findFirst()) to find the first child with a given characteristics (something in the middle of the find() and children() functions. For instance, given this markup: <div id="start"> <div> <span>Hello world</span> <ul class="valid-result"> ... </ul> <ul class="valid-result"> <li> <ul class="not-a-result"> ... </ul> </li> </ul> <div> <ul class="valid-result"> ... </ul> </div> </div> </div> If you ask for $("#start").findFirst('ul') it should return all ul lists that I have tagged with the valid-result class, but not the ul with class not-a-result. It is, this function has to find the first elements that matches with a given selector, but not the inner elements that match this selector. This is the first time I try to code a Jquery function, and what I've already read doesn't helps me too much with this. The function I have developed is this: jQuery.fn.findFirst = function (sel) { return this.map(function() { return $(this).children().map(function() { if ($(this).is(sel)) { return $(this); } else { return $(this).findFirst(sel); } }); }); } It works in the sense it tries to return the expected result, but the format it returns the result is very rare for me. I suppose the problem is something I don't understand about Jquery. Here you have the JFiddle where I'm testing. EDIT The expected result after $("#start").findFirst('ul') is a set with all UL that have the class 'valid-result' BUT it's not possible to use this class because it doesn't exist in a real case (it's just to try to explain the result). This is not equivalent to first(), because first returns only one element!

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• File sizing issue in DOS/FAT

  - by Heather

  I've been tasked with writing a data collection program for a Unitech HT630, which runs a proprietary DOS operating system that can run executables compiled for 16-bit MS DOS with some restrictions. I'm using the Digital Mars C/C++ compiler, which is working well thus far. One of the application requirements is that the data file must be human-readable plain text, meaning the file can be imported into Excel or opened by Notepad. I'm using a variable length record format much like CSV that I've successfully implemented using the C standard library file I/O functions. When saving a record, I have to calculate whether the updated record is larger or smaller than the version of the record currently in the data file. If larger, I first shift all records immediately after the current record forward by the size difference calculated before saving the updated record. EOF is extended automatically by the OS to accommodate the extra data. If smaller, I shift all records backwards by my calculated offset. This is working well, however I have found no way to modify the EOF marker or file size to ignore the data after the end of the last record. Most of the time records will grow in size because the data collection program will be filling some of the empty fields with data when saving a record. Records will only shrink in size when a correction is made on an existing entry, or on a normal record save if the descriptive data in the record is longer than what the program reads in memory. In the situation of a shrinking record, after the last record in the file I'm left with whatever data was sitting there before the shift. I have been writing an EOF delimiter into the file after a "shrinking record save" to signal where the end of my records are and space-filling the remaining data, but then I no longer have a clean file until a "growing record save" extends the size of the file over the space-filled area. The truncate() function in unistd.h does not work (I'm now thinking this is for *nix flavors only?). One proposed solution I've seen involves creating a second file and writing all the data you wish to save into that file, and then deleting the original. Since I only have 4MB worth of disk space to use, this works if the file size is less than 2MB minus the size of my program executable and configuration files, but would fail otherwise. It is very likely that when this goes into production, users would end up with a file exceeding 2MB in size. I've looked at Ralph Brown's Interrupt List and the interrupt reference in IBM PC Assembly Language and Programming and I can't seem to find anything to update the file size or similar. Is reducing a file's size without creating a second file even possible in DOS?

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• how i can use SAX parser

  - by moustafa

  This is what the result should look like when i parse it through a SAX parser http://img13.imageshack.us/img13/6950/75914446.jpg This is the XML source code from which i need to generate the display: <orders> <order> <count>37</count> <price>49.99</price> <book> <isbn>0130897930</isbn> <title>Core Web Programming Second Edition</title> <authors> <count>2</count> <author>Marty Hall</author> <author>Larry Brown</author> </authors> </book> </order> <order> <count>1</count> <price>9.95</price> <yacht> <manufacturer>Luxury Yachts, Inc.</manufacturer> <model>M-1</model> <standardFeatures oars="plastic" lifeVests="none">false</standardFeatures> </yacht> </order> <order> <count>3</count> <price>22.22</price> <book> <isbn>B000059Z4H</isbn> <title>Harry Potter and the Order of the Phoenix</title> <authors> <count>1</count> <author>J.K. Rowling</author> </authors> </book> </order> i really have no clue how to code the functions but i have just set up the parser $xmlParser = xml_parser_create("UTF-8"); xml_parser_set_option($xmlParser, XML_OPTION_CASE_FOLDING, false); xml_set_element_handler($xmlParser, 'startElement', 'endElement'); xml_set_character_data_handler($xmlParser, 'HandleCharacterData'); $fileName = 'orders.xml'; if (!($fp = fopen($fileName, 'r'))){ die('Cannot open the XML file: ' . $fileName); } while ($data = fread($fp, 4096)){ $parsedOkay = xml_parse($xmlParser, $data, feof($fp)); if (!$parsedOkay){ print ("There was an error or the parser was finished."); break; } } xml_parser_free($xmlParser); function startElement($xmlParser, $name, $attribs) { } function endElement($parser, $name) { } function HandleCharacterData($parser, $data) { }

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• Cepstral Analysis for pitch detection

  - by Ohmu

  Hi! I'm looking to extract pitches from a sound signal. Someone on IRC just explain to me how taking a double FFT achieves this. Specifically: take FFT take log of square of absolute value (can be done with lookup table) take another FFT take absolute value I am attempting this using vDSP I can't understand how I didn't come across this technique earlier. I did a lot of hunting and asking questions; several weeks worth. More to the point, I can't understand why I didn't think of it. I am attempting to achieve this with vDSP library. it looks as though it has functions to handle all of these tasks. However, I'm wondering about the accuracy of the final result. I have previously used a technique which scours the frequency bins of a single FFT for local maxima. when it encounters one, it uses a cunning technique (the change in phase since the last FFT) to more accurately place the actual peak within the bin. I am worried that this precision will be lost with this technique I'm presenting here. I guess the technique could be used after the second FFT to get the fundamental accurately. But it kind of looks like the information is lost in step 2. as this is a potentially tricky process, could someone with some experience just look over what I'm doing and check it for sanity? also, I've heard there is an alternative technique involving fitting a quadratic over neighbouring bins. Is this of comparable accuracy? if so, I would favour it, as it doesn't involve remembering bin phases. so questions: does this approach makes sense? Can it be improved? I'm a bit worried about And the log square component; there seems to be a vDSP function to do exactly that: vDSP_vdbcon however, there is no indication it precalculates a log-table -- I assume it doesn't, as the FFT function requires an explicit pre-calculation function to be called and passed into it. and this function doesn't. Is there some danger of harmonics being picked up? is there any cunning way of making vDSP pull out the maxima, biggest first? Can anyone point me towards some research or literature on this technique? the main question: is it accurate enough? Can the accuracy be improved? I have just been told by an expert that the accuracy IS INDEED not sufficient. Is this the end of the line? Pi PS I get SO annoyed (npi) when I want to create tags, but cannot. :| I have suggested to the maintainers that SO keep track of attempted tags, but I'm sure I was ignored. we need tags for vDSP, accelerate framework, cepstral analysis

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• What variable dictates position of non-focused elements in the roundabout plugin?

  - by kristina childs

  Part of the problem here is that i'm not sure what the best language to use in order to find the solution. I search and searched so please forgive if this is already a thread somewhere. I'm using the roundabout plugin to cycle through 3 divs. Each div is 794px wide, which makes the roundabout-in-focus element 794 and the two not in focus 315.218px wide, positioned so half of each is hidden by the in-focus div. This is all well and good, however the total width of the display needs to stay within 1000px (ideally 980px, but i can fudge if need be.) Basically I want to make the non-focused divs be 3/4 hidden by the in-focus div but for the life of me can't figure out what variables i need to edit in order to do it. Unfortunately it's not one of the many easily-changed options like z-index and minScale. i tried minScale but it's clear this isn't going to work. the plugin outputs this code: <li class="roundabout-moveable-item" style="position: absolute; left: -57px; top: 205px; width: 319.982px; height: 149.513px; opacity: 0.7; z-index: 146; font-size: 5.6px;"> i need to find out what changes the left positioning so it's shifted closer to the center of the stage, like this: <li class="roundabout-moveable-item" style="position: absolute; left: 5px; top: 205px; width: 319.982px; height: 149.513px; opacity: 0.7; z-index: 146; font-size: 5.6px;"> i tried playing with the positioning functions of the plugin but all that did was shift everything in tandem left or right. any help is greatly appreciated. this site is going to be awesome once i figure out all this jquery stuff! here is a link to my .js file: http://avalon.eaw.com/scripts/jquery.roundabout2.js i've got an overflow:hidden on the to help guide the positioning of those no-focused items.

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• How do I use a custom #theme function to a fieldset in a drupal module?

  - by Rob Crowell

  I have a module that builds a form that includes a fieldset. Instead of using the <legend> element to render the fieldset title, I want to place this content in a <div> element instead. But I want to change the behavior only for the form returned by my module, so I don't want to place any new functionality into my theme's template.php file. In mymod.module I have defined: // custom rendering function for fieldset elements function theme_mymod_fieldset($element) { return 'test'; } // implement hook_theme function mymod_theme() { return array( 'mymod_fieldset' => array('arguments' => array('element' => NULL)), 'mymod_form' => array('arguments' => array()) ); } // return a form that is based on the 'Basic Account Info' category of the user profile function mymod_form() { // load the user's profile global $user; $account = user_load($user->uid); // load the profile form, and then edit it $form_state = array(); $form = drupal_retrieve_form('user_profile_form', $form_state, $account, 'Basic Account Info'); // set the custom #theme function for this fieldset $form['Basic Account Info']['#theme'] = 'mymod_fieldset'; // more form manipulations // ... return $form; } When my page gets rendered, I expected to see the fieldset representing 'Basic Account Info' to be wholly replaced by my test message 'test'. Instead what happens is that the <fieldset> and <legend> elements are rendered as normal, but with the body of the fieldset replaced by the test message instead, like this: <fieldset> <legend>Basic Account Info</legend> test </fieldset> Why doesn't my #theme function have the chance to replace the entire <fieldset> element? If I wrap a textfield in this function instead, I am able to completely replace the <input> element along with its label. Furthermore, if I provide an override in my site's template.php for theme_fieldset, it works as expected and I am able to completely replace the <fieldset>, so I know it is possible. What's different about providing #theme functions to fieldsets inside a module?

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• Javascript Global Variables Not Working as expected. Help?

  - by capri corn

  I am new to Javascript. I am facing a problem with global variables. I can't figure out that why the global variables are not working as the code looks ok. Please Help me solve this problem. I will breifly explain the code first.I have some text on a page which changes to text field when clicked. When I define the variables inside the functions body the code starts working fine. When these variables are defined globally as in the following code, the console displays this error: the variable is not defined. Here my code: <!DOCTYPE HTML> <html> <head> <title>Span to Text Box - Demo - DOM</title> <script type="text/javascript" language="javascript"> var textNode = document.getElementById('text'); var textValue = textNode.firstChild.nodeValue; var textboxNode = document.getElementById('textbox'); var doneButton = document.getElementById('done'); function change() { textboxNode.setAttribute('value', textValue); textNode.style.display = 'none'; textboxNode.setAttribute('type','text'); doneButton.setAttribute('type','button'); } function changeBack() { textNode.firstChild.nodeValue = textboxNode.value; textNode.style.display = 'block'; textboxNode.setAttribute('type', 'hidden'); doneButton.setAttribute('type','hidden'); } </script> </head> <body> <p id="text" onClick="change()">Click me!</p> <form onSubmit="return false;"> <input type="hidden" id="textbox" /> <input type="hidden" id="done" onClick="changeBack()" value="Done" /> </form> </body> </html> Please Help! Thanks in Advance.

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• Implicit vs explicit getters/setters in AS3, which to use and why?

  - by James

  Since the advent of AS3 I have been working like this: private var loggy:String; public function getLoggy ():String { return loggy; } public function setLoggy ( loggy:String ):void { // checking to make sure loggy's new value is kosher etc... this.loggy = loggy; } and have avoided working like this: private var _loggy:String; public function get loggy ():String { return loggy; } public function set loggy ( loggy:String ):void { // checking to make sure loggy's new value is kosher etc... this.loggy = loggy; } I have avoided using AS3's implicit getters/setters partly so that I can just start typing "get.." and content assist will give me a list of all my getters, and likewise for my setters. I also dislike underscores in my code which turned me off the implicit route. Another reason is that I prefer the feel of this: whateverObject.setLoggy( "loggy's awesome new value!" ); to this: whateverObject.loggy = "loggy's awesome new value!"; I feel that the former better reflects what is actually happening in the code. I am calling functions, not setting values directly. After installing Flash Builder and the great new plugin SourceMate ( which helps to get some of the useful features that FDT is famous into FB ) I realized that when I use SourceMate's "generate getters and setters" feature it automatically sets my code up using the implicit route: private var _loggy:String; public function get loggy ():String { return loggy; } public function set loggy ( loggy:String ):void { // do whatever is needed to check to make sure loggy is an acceptable value this.loggy = loggy; } I figure that these SourceMate people must know what they are doing or they wouldn't be writing workflow enhancement plugins for coding in AS3, so now I am questioning my ways. So my question to you is: Can anyone give me a good reason why I should give up my explicit g/s ways, start using the implicit technique, and embrace those stinky little _underscores for my private vars? Or back me up in my reasons for doing things the way that I do?

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• Setting up Netbeans/Eclipse for Linux Kernel Development

  - by red.october

  Hi: I'm doing some Linux kernel development, and I'm trying to use Netbeans. Despite declared support for Make-based C projects, I cannot create a fully functional Netbeans project. This is despite compiling having Netbeans analyze a kernel binary that was compiled with full debugging information. Problems include: files are wrongly excluded: Some files are incorrectly greyed out in the project, which means Netbeans does not believe they should be included in the project, when in fact they are compiled into the kernel. The main problem is that Netbeans will miss any definitions that exist in these files, such as data structures and functions, but also miss macro definitions. cannot find definitions: Pretty self-explanatory - often times, Netbeans cannot find the definition of something. This is partly a result of the above problem. can't find header files: self-explanatory I'm wondering if anyone has had success with setting up Netbeans for Linux kernel development, and if so, what settings they used. Ultimately, I'm looking for Netbeans to be able to either parse the Makefile (preferred) or extract the debug information from the binary (less desirable, since this can significantly slow down compilation), and automatically determine which files are actually compiled and which macros are actually defined. Then, based on this, I would like to be able to find the definitions of any data structure, variable, function, etc. and have complete auto-completion. Let me preface this question with some points: I'm not interested in solutions involving Vim/Emacs. I know some people like them, but I'm not one of them. As the title suggest, I would be also happy to know how to set-up Eclipse to do what I need While I would prefer perfect coverage, something that only misses one in a million definitions is obviously fine SO's useful "Related Questions" feature has informed me that the following question is related: http://stackoverflow.com/questions/149321/what-ide-would-be-good-for-linux-kernel-driver-development. Upon reading it, the question is more of a comparison between IDE's, whereas I'm looking for how to set-up a particular IDE. Even so, the user Wade Mealing seems to have some expertise in working with Eclipse on this kind of development, so I would certainly appreciate his (and of course all of your) answers. Cheers

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• Runtime.exec causes duplicate JVM to hang indefinitely until killed (Solaris 10)

  - by John

  All, We are running a J2EE application on WebLogic server 9.2 MP2 with a jrockit 64-bit JVM (27.3.1) on Solaris 10. We call use runtime.exec to call an executable called jfmerge to create PDF documents. We have found that in Solaris, when runtime.exec is called, a duplicate JVM is temporarily spawned to kick off the jfmerge process. While this is inefficient (our JVM is 5 GB, thus the duplicated shell JVM is also 5 GB), the major problem lies in the fact that when there is heavy load on this functionality (PDF generation) in our application, sometimes the duplicated JVM never exits. When the JVM hangs, the servers create large issues (extreme application slowness and terminated user sessions) as the entire duplicate JVM get's all of its 5 GB of process size written to disk swap. We have noted the following hung thread correlated with a hung JVM process until the process is manually killed: "[STUCK] ExecuteThread: '17' for queue: 'weblogic.kernel.Default (self-tuning)'" id=3463 idx=0x158 tid=3460 prio=1 alive, in native, daemon at jrockit/io/FileNativeIO.readBytesPinned(Ljava/io/FileDescriptor;[BII)I(Native Method) at jrockit/io/FileNativeIO.readBytes(FileNativeIO.java:30) at java/io/FileInputStream.readBytes([BII)I(FileInputStream.java) at java/io/FileInputStream.read(FileInputStream.java:194) at java/lang/UNIXProcess$DeferredCloseInputStream.read(UNIXProcess.java:227) at java/io/BufferedInputStream.fill(BufferedInputStream.java:218) at java/io/BufferedInputStream.read(BufferedInputStream.java:235) ^-- Holding lock: java/io/BufferedInputStream@0xfffffffec6510470[thin lock] at gov/v3/common/formgeneration/sessionbean/FormsBean.getProcessStatus(FormsBean.java:809) at gov/v3/common/formgeneration/sessionbean/FormsBean.createPDF(FormsBean.java:750) at gov/v3/common/formgeneration/sessionbean/FormsBean.getTemplateDetails(FormsBean.java:450) at gov/v3/common/formgeneration/sessionbean/FormsBean.generateSinglePDF(FormsBean.java:1371) at gov/v3/common/formgeneration/sessionbean/FormsBean.generatePDF(FormsBean.java:263) at gov/v3/common/formgeneration/sessionbean/FormsBean.endorseDocument(FormsBean.java:2377) at gov/v3/common/formgeneration/sessionbean/Forms_qaco28_EOImpl.endorseDocument(Forms_qaco28_EOImpl.java:214) at gov/v3/delegates/common/FormsAndNoticesDelegate.endorseDocument(FormsAndNoticesDelegate.java:128) at gov/v3/actions/common/EndorseDocumentAction.executeRequest(EndorseDocumentAction.java:68) at gov/v3/fwk/controller/struts/action/V3CommonDispatchAction.dispatchToExecuteMethod(V3CommonDispatchAction.java:532) at gov/v3/fwk/controller/struts/action/V3CommonDispatchAction.executeBaseAction(V3CommonDispatchAction.java:336) at gov/v3/fwk/controller/struts/action/V3BaseDispatchAction.execute(V3BaseDispatchAction.java:69) at org/apache/struts/action/RequestProcessor.processActionPerform(RequestProcessor.java:484) at gov/v3/fwk/controller/struts/requestprocessor/V3TilesRequestProcessor.processActionPerform(V3TilesRequestProcessor.java:384) at org/apache/struts/action/RequestProcessor.process(RequestProcessor.java:274) at org/apache/struts/action/ActionServlet.process(ActionServlet.java:1482) at org/apache/struts/action/ActionServlet.doGet(ActionServlet.java:507) at gov/v3/fwk/controller/struts/servlet/V3ControllerServlet.doGet(V3ControllerServlet.java:110) at javax/servlet/http/HttpServlet.service(HttpServlet.java:743) at javax/servlet/http/HttpServlet.service(HttpServlet.java:856) at weblogic/servlet/internal/StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227) at weblogic/servlet/internal/StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125) at weblogic/servlet/internal/ServletStubImpl.execute(ServletStubImpl.java:283) at weblogic/servlet/internal/ServletStubImpl.execute(ServletStubImpl.java:175) at weblogic/servlet/internal/WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3231) at weblogic/security/acl/internal/AuthenticatedSubject.doAs(AuthenticatedSubject.java:321) at weblogic/security/service/SecurityManager.runAs(SecurityManager.java:121) at weblogic/servlet/internal/WebAppServletContext.securedExecute(WebAppServletContext.java:2002) at weblogic/servlet/internal/WebAppServletContext.execute(WebAppServletContext.java:1908) at weblogic/servlet/internal/ServletRequestImpl.run(ServletRequestImpl.java:1362) at weblogic/work/ExecuteThread.execute(ExecuteThread.java:209) at weblogic/work/ExecuteThread.run(ExecuteThread.java:181) at jrockit/vm/RNI.c2java(JJJJJ)V(Native Method) -- end of trace We would like to do a couple of things: 1.) Prevent the spawning of a duplicate JVM, as we do not need any of it's functions when executing the simple jfmerge executable, and it creates massive overhead. 2.) In the short term at least prevent this duplicate JVM from handing indefinitely.

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• log4bash: Cannot find a way to add MaxBackupIndex to this logger implementation

  - by Syffys

  I have been trying to modify this log4bash implementation but I cannot manage to make it work. Here's a sample: #!/bin/bash TRUE=1 FALSE=0 ############### Added for testing log4bash_LOG_ENABLED=$TRUE log4bash_rootLogger=$TRACE,f,s log4bash_appender_f=file log4bash_appender_f_dir=$(pwd) log4bash_appender_f_file=test.log log4bash_appender_f_roll_format=%Y%m log4bash_appender_f_roll=$TRUE log4bash_appender_f_maxBackupIndex=10 #################################### log4bash_abs(){ if [ "${1:0:1}" == "." ]; then builtin echo ${rootDir}/${1} else builtin echo ${1} fi } log4bash_check_app_dir(){ if [ "$log4bash_LOG_ENABLED" -eq $TRUE ]; then dir=$(log4bash_abs $1) if [ ! -d ${dir} ]; then #log a seperation line mkdir $dir fi fi } # Delete old log files # $1 Log directory # $2 Log filename # $3 Log filename suffix # $4 Max backup index log4bash_delete_old_files(){ ##### Added for testing builtin echo "Running log4bash_delete_old_files $@" &2 ##### if [ "$log4bash_LOG_ENABLED" -eq $TRUE ] && [ -n "$3" ] && [ "$4" -gt 0 ]; then local directory=$(log4bash_abs $1) local filename=$2 local maxBackupIndex=$4 local suffix=$(echo "${3}" | sed -re 's/[^.]/?/g') local logFileList=$(find "${directory}" -mindepth 1 -maxdepth 1 -name "${filename}${suffix}" -type f | xargs ls -1rt) local fileCnt=$(builtin echo -e "${logFileList}" | wc -l) local fileToDeleteCnt=$(($fileCnt-$maxBackupIndex)) local fileToDelete=($(builtin echo -e "${logFileList}" | head -n "${fileToDeleteCnt}" | sed ':a;N;$!ba;s/\n/ /g')) ##### Added for testing builtin echo "log4bash_delete_old_files About to start deletion ${fileToDelete[@]}" &2 ##### if [ ${fileToDeleteCnt} -gt 0 ]; then for f in "${fileToDelete[@]}"; do #### Added for testing builtin echo "Removing file ${f}" &2 #### builtin eval rm -f ${f} done fi fi } #Appender # $1 Log directory # $2 Log file # $3 Log file roll ? # $4 Appender Name log4bash_filename(){ builtin echo "Running log4bash_filename $@" &2 local format local filename log4bash_check_app_dir "${1}" if [ ${3} -eq 1 ];then local formatProp=${4}_roll_format format=${!formatProp} if [ -z ${format} ]; then format=$log4bash_appender_file_format fi local suffix=.`date "+${format}"` filename=${1}/${2}${suffix} # Old log files deletion local previousFilenameVar=int_${4}_file_previous local maxBackupIndexVar=${4}_maxBackupIndex if [ -n "${!maxBackupIndexVar}" ] && [ "${!previousFilenameVar}" != "${filename}" ]; then builtin eval export $previousFilenameVar=$filename log4bash_delete_old_files "${1}" "${2}" "${suffix}" "${!maxBackupIndexVar}" else builtin echo "log4bash_filename $previousFilenameVar = ${!previousFilenameVar}" fi else filename=${1}/${2} fi builtin echo $filename } ######################## Added for testing filename_caller(){ builtin echo "filename_caller Call $1" output=$(log4bash_abs $(log4bash_filename "${log4bash_appender_f_dir}" "${log4bash_appender_f_file}" "1" "log4bash_appender_f" )) builtin echo ${output} } #### Previous logs generation for i in {1101..1120}; do file="${log4bash_appender_f_file}.2012${i:2:3}" builtin echo "${file} $i" touch -m -t "2012${i}0000" ${log4bash_appender_f_dir}/$file done for i in {1..4}; do filename_caller $i done I expect log4bash_filename function to step into the following if only when the calculated log filename is different from the previous one: if [ -n "${!maxBackupIndexVar}" ] && [ "${!previousFilenameVar}" != "${filename}" ]; then For this scenario to apply, I'd need ${!previousFilenameVar} to be correctly set, but it's not the case, so log4bash_filename steps into this if all the time which is really not necessary... It looks like the issue is due to the following line not working properly: builtin eval export $previousFilenameVar=$filename I have a some theories to explain why: in the original code, functions are declared and exported as readonly which makes them unable to modify global variable. I removed readonly declarations in the above sample, but probleme persists. Function calls are performed in $() which should make them run into seperated shell instances so variable modified are not exported to the main shell But I cannot manage to find a workaround to this issue... Any help is appreciated, thanks in advance!

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• In a PHP project, how do you organize and access your helper objects?

  - by Pekka

  How do you organize and manage your helper objects like the database engine, user notification, error handling and so on in a PHP based, object oriented project? Say I have a large PHP CMS. The CMS is organized in various classes. A few examples: the database object user management an API to create/modify/delete items a messaging object to display messages to the end user a context handler that takes you to the right page a navigation bar class that shows buttons a logging object possibly, custom error handling etc. I am dealing with the eternal question, how to best make these objects accessible to each part of the system that needs it. my first apporach, many years ago was to have a $application global that contained initialized instances of these classes. global $application; $application->messageHandler->addMessage("Item successfully inserted"); I then changed over to the Singleton pattern and a factory function: $mh =&factory("messageHandler"); $mh->addMessage("Item successfully inserted"); but I'm not happy with that either. Unit tests and encapsulation become more and more important to me, and in my understanding the logic behind globals/singletons destroys the basic idea of OOP. Then there is of course the possibility of giving each object a number of pointers to the helper objects it needs, probably the very cleanest, resource-saving and testing-friendly way but I have doubts about the maintainability of this in the long run. Most PHP frameworks I have looked into use either the singleton pattern, or functions that access the initialized objects. Both fine approaches, but as I said I'm happy with neither. I would like to broaden my horizon on what is possible here and what others have done. I am looking for examples, additional ideas and pointers towards resources that discuss this from a long-term, real-world perspective. Also, I'm interested to hear about specialized, niche or plain weird approaches to the issue. Bounty I am following the popular vote in awarding the bounty, the answer which is probably also going to give me the most. Thank you for all your answers!

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