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• How to learn proper C++?

  - by Chris

  While reading a long series of really, really interesting threads, I've come to a realization: I don't think I really know C++. I know C, I know classes, I know inheritance, I know templates (& the STL) and I know exceptions. Not C++. To clarify, I've been writing "C++" for more than 5 years now. I know C, and I know that C and C++ share a common subset. What I've begun to realize, though, is that more times than not, I wind up treating C++ something vaguely like "C with classes," although I do practice RAII. I've never used Boost, and have only read up on TR1 and C++0x - I haven't used any of these features in practice. I don't use namespaces. I see a list of #defines, and I think - "Gracious, that's horrible! Very un-C++-like," only to go and mindlessly write class wrappers for the sake of it, and I wind up with large numbers (maybe a few per class) of static methods, and for some reason, that just doesn't seem right lately. The professional in me yells "just get the job done," the academic yells "you should write proper C++ when writing C++" and I feel like the point of balance is somewhere in between. I'd like to note that I don't want to program "pure" C++ just for the sake of it. I know several languages. I have a good feel for what "Pythonic" is. I know what clean and clear PHP is. Good C code I can read and write better than English. The issue is that I learned C by example, and picked up C++ as a "series of modifications" to C. And a lot of my early C++ work was creating class wrappers for C libraries. I feel like my own personal C-heavy background while learning C++ has sort of... clouded my acceptance of C++ in it's own right, as it's own language. Do the weathered C++ lags here have any advice for me? Good examples of clean, sharp C++ to learn from? What habits of C does my inner-C++ really need to break from? My goal here is not to go forth and trumpet "good" C++ paradigm from rooftops for the sake of it. C and C++ are two different languages, and I want to start treating them that way. How? Where to start? Thanks in advance! Cheers, -Chris

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• C# Property Access vs Interface Implementation

  - by ehdv

  I'm writing a class to represent a Pivot Collection, the root object recognized by Pivot. A Collection has several attributes, a list of facet categories (each represented by a FacetCategory object) and a list of items (each represented by a PivotItem object). Therefore, an extremely simplified Collection reads: public class Collection { private List<FacetCategory> categories; private List<PivotItem> items; // other attributes } What I'm unsure of is how to properly grant access to those two lists. Because declaration order of both facet categories and items is visible to the user, I can't use sets, but the class also shouldn't allow duplicate categories or items. Furthermore, I'd like to make the Collection object as easy to use as possible. So my choices are: Have Collection implement IList<PivotItem> and have accessor methods for FacetCategory: In this case, one would add an item to Collection foo by writing foo.Add(bar). This works, but since a Collection is equally both kinds of list making it only pass as a list for one type (category or item) seems like a subpar solution. Create nested wrapper classes for List (CategoryList and ItemList). This has the advantage of making a consistent interface but the downside is that these properties would no longer be able to serve as lists (because I need to override the non-virtual Add method I have to implement IList rather than subclass List. Implicit casting wouldn't work because that would return the Add method to its normal behavior. Also, for reasons I can't figure out, IList is missing an AddRange method... public class Collection { private class CategoryList: IList<FacetCategory> { // ... } private readonly CategoryList categories = new CategoryList(); private readonly ItemList items = new ItemList(); public CategoryList FacetCategories { get { return categories; } set { categories.Clear(); categories.AddRange(value); } } public ItemList Items { get { return items; } set { items.Clear(); items.AddRange(value); } } } Finally, the third option is to combine options one and two, so that Collection implements IList<PivotItem> and has a property FacetCategories. Question: Which of these three is most appropriate, and why?

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• How is "clean" testing done on the Macintosh without virtualization?

  - by Schnapple

  One of the things I've run across on Windows is when a web browser plugin or program you're developing makes an assumption that something is installed that, by default, isn't always present on Windows. A perfect example would be .NET - a whole lot of people running Windows XP have never installed any versions of .NET and so the installer needs to detect and remedy this if necessary. The way I've been testing this in Windows is to have a virtual machine with a snapshot of a clean, patched, but otherwise untouched install of XP or Vista or 7 or whatever. When I'm done testing I just discard any changes since the snapshot. Works great. I'm now developing something for the Macintosh, a platform which is very new to me, and I'm seeing that virtualization does not appear to be an option. It's explicitly forbidden in the EULA of Mac OS X, it's only allowed from Mac OS X Server, which seeing as how I'm targeting an end product is of no use to me, and the one program I see which can virtualize it - VirtualBox - only supports the server and actively nukes any discussion of running the consumer/client version of Mac OS X. And the only instructions I find anywhere on the topic seem to involve the use of "hacking" programs which is very much incompatible with the full-time gig I'm trying to do this for. So it looks like virtualization is out, but at various points I'm going to want or need to simulate what it's like to install and run this software on a "clean" Macintosh. How do people usually do this? Just buy multiple Macintoshes and use Time Machine? Am I thinking about this all wrong and everything Just Works? To be clear I'm not trying to run Mac OS X on a Windows machine. I have a Macintosh, I'm fine with virtualizing Mac OS X on Apple hardware, I'm just not seeing a route to making the non-Server version do this. I'm aware that Mac OS X Server can be virtualized but that's not what I'm going for. I'm aware that there are unsanctioned/unsupported methods of making Mac OS X run in virtualization programs like VirtualBox but for legal reasons I am not interested in those. My question is not "how can I do this?" but rather "so this thing I do on Windows seems to not be possible, generally, on the Macintosh, so what do people do to achieve what I'm going for?"

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• Hierarchy inheritance

  - by reito

  I had faced the problem. In my C++ hierarchy tree I have two branches for entities of difference nature, but same behavior - same interface. I created such hierarchy trees (first in image below). And now I want to work with Item or Base classes independetly of their nature (first or second). Then I create one abstract branch for this use. My mind build (second in image below). But it not working. Working scheme seems (third in image below). It's bad logic, I think... Do anybody have some ideas about such hierarchy inheritance? How make it more logical? More simple for understanding? Image Sorry for my english - russian internet didn't help:) Update: You ask me to be more explicit, and I will be. In my project (plugins for Adobe Framemaker) I need to work with dialogs and GUI controls. In some places I working with WinAPI controls, and some other places with FDK (internal Framemaker) controls, but I want to work throw same interface. I can't use one base class and inherite others from it, because all needed controls - is a hierarchy tree (not one class). So I have one hierarchy tree for WinAPI controls, one for FDK and one abstract tree to use anyone control. For example, there is an Edit control (WinEdit and FdkEdit realization), a Button control (WinButton and FdkButton realization) and base entity - Control (WinControl and FdkControl realization). For now I can link my classes in realization trees (Win and Fdk) with inheritence between each of them (WinControl is base class for WinButton and WinEdit; FdkControl is base class for FdkButton and FdkEdit). And I can link to abstract classes (Control is base class for WinControl and FdkControl; Edit is base class for WinEdit and FdkEdit; Button is base class for WinButton and FdkButton). But I can't link my abstract tree - compiler swears. In fact I have two hierarchy trees, that I want to inherite from another one. Update: I have done this quest! :) I used the virtual inheritence and get such scheme (http://img12.imageshack.us/img12/7782/99614779.png). Abstract tree has only absolute abstract methods. All inheritence in abstract tree are virtual. Link from realization tree to abstract are virtual. On image shown only one realization tree for simplicity. Thanks for help!

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• multithreading with database

  - by Darsin

  I am looking out for a strategy to utilize multithreading (probably asynchronous delegates) to do a synchronous operation. I am new to multithreading so i will outline my scenario first. This synchronous operation right now is done for one set of data (portfolio) based on the the parameters provided. The (psudeo-code) implementation is given below: public DataSet DoTests(int fundId, DateTime portfolioDate) { // Get test results for the portfolio // Call the database adapter method, which in turn is a stored procedure, // which in turns runs a series of "rule" stored procs and fills a local temp table and returns it back. DataSet resultsDataSet = GetTestResults(fundId, portfolioDate); try { // Do some local processing on the results DoSomeProcessing(resultsDataSet); // Save the results in Test, TestResults and TestAllocations tables in a transaction. // Sets a global transaction which is provided to all the adapter methods called below // It is defined in the Base class StartTransaction("TestTransaction"); // Save Test and get a testId int testId = UpdateTest(resultsDataSet); // Adapter method, uses the same transaction // Update testId in the other tables in the dataset UpdateTestId(resultsDataSet, testId); // Update TestResults UpdateTestResults(resultsDataSet); // Adapter method, uses the same transaction // Update TestAllocations UpdateTestAllocations(resultsDataSet); // Adapter method, uses the same transaction // It is defined in the base class CommitTransaction("TestTransaction"); } catch { RollbackTransaction("TestTransaction"); } return resultsDataSet; } Now the requirement is to do it for multiple set of data. One way would be to call the above DoTests() method in a loop and get the data. I would prefer doing it in parallel. But there are certain catches: StartTransaction() method creates a connection (and transaction) every time it is called. All the underlying database tables, procedures are the same for each call of DoTests(). (obviously). Thus my question are: Will using multithreading anyway improve performance? What are the chances of deadlock especially when new TestId's are being created and the Tests, TestResults and TestAllocations are being saved? How can these deadlocked be handled? Is there any other more efficient way of doing the above operation apart from looping over the DoTests() method repeatedly?

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• translating specifications into query predicates

  - by Jeroen

  I'm trying to find a nice and elegant way to query database content based on DDD "specifications". In domain driven design, a specification is used to check if some object, also known as the candidate, is compliant to a (domain specific) requirement. For example, the specification 'IsTaskDone' goes like: class IsTaskDone extends Specification<Task> { boolean isSatisfiedBy(Task candidate) { return candidate.isDone(); } } The above specification can be used for many purposes, e.g. it can be used to validate if a task has been completed, or to filter all completed tasks from a collection. However, I want to re-use this, nice, domain related specification to query on the database. Of course, the easiest solution would be to retrieve all entities of our desired type from the database, and filter that list in-memory by looping and removing non-matching entities. But clearly that would not be optimal for performance, especially when the entity count in our db increases. Proposal So my idea is to create a 'ConversionManager' that translates my specification into a persistence technique specific criteria, think of the JPA predicate class. The services looks as follows: public interface JpaSpecificationConversionManager { <T> Predicate getPredicateFor(Specification<T> specification, Root<T> root, CriteriaQuery<?> cq, CriteriaBuilder cb); JpaSpecificationConversionManager registerConverter(JpaSpecificationConverter<?, ?> converter); } By using our manager, the users can register their own conversion logic, isolating the domain related specification from persistence specific logic. To minimize the configuration of our manager, I want to use annotations on my converter classes, allowing the manager to automatically register those converters. JPA repository implementations could then use my manager, via dependency injection, to offer a find by specification method. Providing a find by specification should drastically reduce the number of methods on our repository interface. In theory, this all sounds decent, but I feel like I'm missing something critical. What do you guys think of my proposal, does it comply to the DDD way of thinking? Or is there already a framework that does something identical to what I just described?

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• Public class: The best way to store and access NSMutableDictionary?

  - by meridimus

  I have a class to help me store persistent data across sessions. The problem is I want to store a running sample of the property list or "plist" file in an NSMutableArray throughout the instance of the Persistance class so I can read and edit the values and write them back when I need to. The problem is, as the methods are publicly defined I cannot seem to access the declared NSMutableDictionary without errors. The particular error I get on compilation is: warning: 'Persistence' may not respond to '+saveData' So it kind of renders my entire process unusable until I work out this problem. Here is my full persistence class (please note, it's unfinished so it's just to show this problem): Persistence.h #import <UIKit/UIKit.h> #define kSaveFilename @"saveData.plist" @interface Persistence : NSObject { NSMutableDictionary *saveData; } @property (nonatomic, retain) NSMutableDictionary *saveData; + (NSString *)dataFilePath; + (NSDictionary *)getSaveWithCampaign:(NSUInteger)campaign andLevel:(NSUInteger)level; + (void)writeSaveWithCampaign:(NSUInteger)campaign andLevel:(NSUInteger)level withData:(NSDictionary *)saveData; + (NSString *)makeCampaign:(NSUInteger)campaign andLevelKey:(NSUInteger)level; @end Persistence.m #import "Persistence.h" @implementation Persistence @synthesize saveData; + (NSString *)dataFilePath { NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES); NSString *documentsDirectory = [paths objectAtIndex:0]; return [documentsDirectory stringByAppendingPathComponent:kSaveFilename]; } + (NSDictionary *)getSaveWithCampaign:(NSUInteger)campaign andLevel:(NSUInteger)level { NSString *filePath = [self dataFilePath]; if([[NSFileManager defaultManager] fileExistsAtPath:filePath]) { NSLog(@"File found"); [[self saveData] setDictionary:[[NSDictionary alloc] initWithContentsOfFile:filePath]]; // This is where the warning "warning: 'Persistence' may not respond to '+saveData'" occurs NSString *campaignAndLevelKey = [self makeCampaign:campaign andLevelKey:level]; NSDictionary *campaignAndLevelData = [[self saveData] objectForKey:campaignAndLevelKey]; return campaignAndLevelData; } else { return nil; } } + (void)writeSaveWithCampaign:(NSUInteger)campaign andLevel:(NSUInteger)level withData:(NSDictionary *)saveData { NSString *campaignAndLevelKey = [self makeCampaign:campaign andLevelKey:level]; NSDictionary *saveDataWithKey = [[NSDictionary alloc] initWithObjectsAndKeys:saveData, campaignAndLevelKey, nil]; //[campaignAndLevelKey release]; [saveDataWithKey writeToFile:[self dataFilePath] atomically:YES]; } + (NSString *)makeCampaign:(NSUInteger)campaign andLevelKey:(NSUInteger)level { return [[NSString stringWithFormat:@"%d - ", campaign+1] stringByAppendingString:[NSString stringWithFormat:@"%d", level+1]]; } @end I call this class like any other, by including the header file in my desired location: @import "Persistence.h" Then I call the function itself like so: NSDictionary *tempSaveData = [[NSDictionary alloc] [Persistence getSaveWithCampaign:currentCampaign andLevel:currentLevel]];

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• Can this way of storing typed objects be improved?

  - by Pindatjuh

  This is an "can it be improved"-question. Topic: Storing typed objects in memory. Background information: I'm building a compiler for the x86-32 Windows platform for my language. My goal includes typed objects. Idea: Every primitive is a semi-class (it can be used as if it was a normal class, but it's stored more compact). Every class is represented by primitives and some meta-data (containing class-properties, inheritance stuff, etc.). The meta-data is complex: it doesn't use fields but instead context-switches. For primitives, the meta-data is very small, compared to a "real" class, which is alot bigger. This enables another idea that "primitives are objects", in my language, which I found nessecairy. Example: If I have an array of 32 booleans, then the pure content of this array is exactly 4 byte (32 bits of booleans). The meta-data will contain flags that the type is an array of booleans, which contains 32 entries. The meta-data is very compacted, on bit-level: using a sort of "packing" mechanism, which is read by a FSM at runtime, when doing inspection of the type (like when passing the object to methods for checking, etc.) For instance (read from left to right, top to bottom, remember vertical position when going to the right, and check nearest column header for meaning of switch): Primitive? Array? Type-Meta 1 Byte? || Size (1 byte) 1 1 [...] 1 [...] done 0 2 Bytes? || Size (2 bytes) 1 [...] done || Size (4 bytes) 0 [...] done Integer? 1 Byte? 2 Bytes? 0 1 0 1 done 1 done 0 done Boolean? Byte? 0 1 0 done 1 done More-Primitives 0 .... Class-Stuff (Huge) 0 ... (After reaching done the data is inserted. || = byte alignment. [...] is variable sized. ... is not described here, for simplicity. And let's call them cost-based-data-structures.) For an array of 32 booleans containing all true values, the memory for this type would be (read top-down): 1 Primitive 1 Array 1 ArrayType: Primitive 0 Not-Array 0 Not-Integer 1 Boolean 0 Not-Byte (thus bit) 1 Integer Size: 1 Byte 00100000 Array size 01010101 01010101 01010101 01010101 Data (user defined) Thus, 8 bytes represent 32 booleans in an array: 11100101 00100000 01010101 01010101 01010101 01010101 How can I improve this? (Both performance- and memory-consumption wise)

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• Hibernate3: Self-Referencing Objects

  - by monojohnny

  Need some help on understanding how to do this; I'm going to be running recursive 'find' on a file system and I want to keep the information in a single DB table - with a self-referencing hierarchial structure: This is my DB Table structure I want to populate. DirObject Table: id int NOT NULL, name varchar(255) NOT NULL, parentid int NOT NULL); Here is the proposed Java Class I want to map (Fields only shown): public DirObject { int id; String name; DirObject parent; ... For the 'root' directory was going to use parentid=0; real ids will start at 1, and ideally I want hibernate to autogenerate the ids. Can somebody provide a suggested mapping file for this please; as a secondary question I thought about doing the Java Class like this instead: public DirObject { int id; String name; List<DirObject> subdirs; Could I use the same data model for either of these two methods ? (With a different mapping file of course). --- UPDATE: so I tried the mapping file suggested below (thanks!), repeated here for reference: <hibernate-mapping> <class name="my.proj.DirObject" table="category"> ... <set name="subDirs" lazy="true" inverse="true"> <key column="parentId"/> <one-to-many class="my.proj.DirObject"/> </set> <many-to-one name="parent" class="my.proj.DirObject" column="parentId" cascade="all" /> </class> ...and altered my Java class to have BOTH 'parentid' and 'getSubDirs' [returning a 'HashSet']. This appears to work - thanks, but this is the test code I used to drive this - I think I'm not doing something right here, because I thought Hibernate would take care of saving the subordinate objects in the Set without me having to do this explicitly ? DirObject dirobject=new DirObject(); dirobject.setName("/files"); dirobject.setParent(dirobject); DirObject d1, d2; d1=new DirObject(); d1.setName("subdir1"); d1.setParent(dirobject); d2=new DirObject(); d2.setName("subdir2"); d2.setParent(dirobject); HashSet<DirObject> subdirs=new HashSet<DirObject>(); subdirs.add(d1); subdirs.add(d2); dirobject.setSubdirs(subdirs); session.save(dirobject); session.save(d1); session.save(d2);

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• NSArraycontroller selectionIndexes bindings

  - by Michael Scherbaum

  Hi all, I have the following set-up: A Window that has a splitView in which I display I NSCollectionView in the left view and a detailView in the right view. Both views are set-up in separate xibs. Furthermore I have a Datacontroller (of class NSArrayController) that manages a mutable Array of NSMutableDictionaries (moviesForChoice). The dataController is set-up as application delegate. The movie objects in the array have properties like (name, plot, genre etc.) so far so good... In the xib for the NScollectionview I bound a NSArraycontroller content property to my datacontroller via Application.delegate.moviesForChoice The collectionView accesses the arraycontroller.arrrangedObjects and arraycontroller.selectionIndexes. This works fine the contents are displayed and the selection works fine in the collectionview (my collectionviewItem renders a selection color) In the xib for the detailView I want to display information for the selected object in the collectionview. Therefore I also added an arraycontroller to the xib, bound the content aray to Application.delegate.moviesForChoice and bound the NSTextfields in the view to e.g. arraycontroller.selection.name Here comes my issue: everytime I open the window with the two xibs, my collectionview displays all movies that are for choice correctly, and the detailview displays the information for the 1st object in my collectionview. Whenever I click on a different movie in the collectionView the res. item renders a selection color, but the detailView doesn't update. My understanding of it would be that the DataController is not informed about updates in the selectionIndexes and can therefore not trigger an update in the detailView. Correct me if I'm wrong... To remedy this I tried to bind the selectionIndexes property of the arraycontroller in the collectionView xib to Application.delegate.moviesForChoice.selecionIndexes but this failed with: addObserver:forKeyPath:options:context:] is not supported. Key path: selectionIndexes I could imagine that this means that the datacontroller is not KVO compliant for my Array moviesForChoice, but I implemented the following methods for it: -(void)insertObject:(NSDictionary *)dict inMoviesForChoiceAtIndex:(NSUInteger)index { [moviesForChoice insertObject:dict atIndex:index]; } -(void)removeObjectFromMoviesForChoiceAtIndex:(NSUInteger)index { [moviesForChoice removeObjectAtIndex:index]; } -(void)setMoviesForChoice:(NSMutableArray *)a { moviesForChoice = a; } -(NSArray*)moviesForChoice { return moviesForChoice; } -(NSUInteger)countOfMoviesForChoice { return [moviesForChoice count]; } - (void)addMovieForChoiceObject:(Movie *)anObject { [moviesForChoice addObject:anObject]; } So where am I wrong? How do I correctly bind to the selectionIndexes? You help is much appreciated! M

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• how to create a system-wide independent universal counter object primarily for Database keys?

  - by andora

  I would like to create/use a system-wide independent universal 'counter object' that can be called via COM in a thread-safe manner. The counter object will be passed an ID to identify which counter to return, handle the counting, 'persist' the count (occasionally), have reasonable performance (as fast as possible) perhaps capable of 1000 counts per second or better (1mS) and be accessible cross-process/out-of-process. The current count status must be persisted between object restarts/shutdowns. The counter object is liklely to be a 'singleton' type object implemented in some form of free-threaded dictionary, containing maybe 10 counters (perhaps 50 max). The count needs to be monotonic and consistent, (ie: guaranteed unique sequential values). Each counter should have a few methods, like reset, inc, dec, set, clear, remove. As a luxury, I would like to have a variable-increment (ie: 'step by' value). To support thread-safefty, perhaps some sorm of critical-section or mutex call. It just needs to return a long/4byte signed integer. I really want something that can be called from anywhere, including VBScript, so I figure COM is my preferred solution. The primary use of this is for database keys. I am unable to use autoinc or guid type keys and have ruled out database-generated counting systems at this point. I've spent days researching this and I have really struggled to find a solution. The best I can find is a free-threaded dictionary object that can be instantiated using COM+ from Motobit - it seems to offer all the 'basics' and I guess I could create some form of wrapper for this. So, here are my questions: Does such a 'general purpose counter-object already exist? Can you direct me to it? (MS did do an IIS/ASP object called 'MSWC.Counter' but this isn't 'cross-process'/ out-of-process component and isn't thread-safe. (but if it was, it would do!) What is the best way of creating such a Component? (I'd prefer VB6 right-now, [don't ask!] but can do in VB.NET2005 if I had to). I don't have the skills/knowledge/tools to use anything else. I am desparate for a workable solution. I need specific guidance! If anybody can code something up for me I am prepared to pay for it.

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• How can I create the XML::Simple data structure using a Perl XML SAX parser?

  - by DVK

  Summary: I am looking a fast XML parser (most likely a wrapper around some standard SAX parser) which will produce per-record data structure 100% identical to those produced by XML::Simple. Details: We have a large code infrastructure which depends on processing records one-by-one and expects the record to be a data structure in a format produced by XML::Simple since it always used XML::Simple since early Jurassic era. An example simple XML is: <root> <rec><f1>v1</f1><f2>v2</f2></rec> <rec><f1>v1b</f1><f2>v2b</f2></rec> <rec><f1>v1c</f1><f2>v2c</f2></rec> </root> And example rough code is: sub process_record { my ($obj, $record_hash) = @_; # do_stuff } my $records = XML::Simple->XMLin(@args)->{root}; foreach my $record (@$records) { $obj->process_record($record) }; As everyone knows XML::Simple is, well, simple. And more importantly, it is very slow and a memory hog—due to being a DOM parser and needing to build/store 100% of data in memory. So, it's not the best tool for parsing an XML file consisting of large amount of small records record-by-record. However, re-writing the entire code (which consist of large amount of "process_record"-like methods) to work with standard SAX parser seems like an big task not worth the resources, even at the cost of living with XML::Simple. I'm looking for an existing module which will probably be based on a SAX parser (or anything fast with small memory footprint) which can be used to produce $record hashrefs one by one based on the XML pictured above that can be passed to $obj->process_record($record) and be 100% identical to what XML::Simple's hashrefs would have been. I don't care much what the interface of the new module is; e.g whether I need to call next_record() or give it a callback coderef accepting a record.

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• Sorting a list of colors in one dimension?

  - by Ptah- Opener of the Mouth

  I would like to sort a one-dimensional list of colors so that colors that a typical human would perceive as "like" each other are near each other. Obviously this is a difficult or perhaps impossible problem to get "perfectly", since colors are typically described with three dimensions, but that doesn't mean that there aren't some sorting methods that look obviously more natural than others. For example, sorting by RGB doesn't work very well, as it will sort in the following order, for example: (1) R=254 G=0 B=0 (2) R=254 G=255 B=0 (3) R=255 G=0 B=0 (4) R=255 G=255 B=0 That is, it will alternate those colors red, yellow, red, yellow, with the two "reds" being essentially imperceivably different than each other, and the two yellows also being imperceivably different from each other. But sorting by HLS works much better, generally speaking, and I think HSL even better than that; with either, the reds will be next to each other, and the yellows will be next to each other. But HLS/HSL has some problems, too; things that people would perceive as "black" could be split far apart from each other, as could things that people would perceive as "white". Again, I understand that I pretty much have to accept that there will be some splits like this; I'm just wondering if anyone has found a better way than HLS/HSL. And I'm aware that "better" is somewhat arbitrary; I mean "more natural to a typical human". For example, a vague thought I've had, but have not yet tried, is perhaps "L is the most important thing if it is very high or very low", but otherwise it is the least important. Has anyone tried this? Has it worked well? What specifically did you decide "very low" and "very high" meant? And so on. Or has anyone found anything else that would improve upon HSL? I should also note that I am aware that I can define a space-filling curve through the cube of colors, and order them one-dimensionally as they would be encountered while travelling along that curve. That would eliminate perceived discontinuities. However, it's not really what I want; I want decent overall large-scale groupings more than I want perfect small-scale groupings. Thanks in advance for any help.

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• iPhone: Can't animate contentInset while animating Nav Bar show/hide

  - by Cuzog

  In my app, I have a table view. When the user clicks a button, a UIView overlays part of that table view. It's essentially a partial modal. That table view is intentionally still scrollable while that modal is active. To allow the user to scroll to the bottom of the table view, I change the contentInset and scrollIndicatorInsets values to adjust for the smaller area above the modal. When the modal is taken away, I reset those inset values. The problem is that when the user has scrolled to the bottom of the newly adjusted inset and then dismisses the modal, the table view jumps abruptly to a new scroll position because the inset is changed instantly. I would like to animate it so there is a transition, but the beginAnimation/commitAnimations methods aren't affecting it for some reason. Edit: More info. I found the conflict. When presenting the modal, I also hide the navigation bar. The navigation bar natively animates the table view up and down as it shows and hides. When I stop animating the navigation bar, the inset animation works fine. Does anyone know what I can do to work around this conflict? Do I have to wait for the navigation bar animation to finish before adjusting the inset? If so, how to I hook onto that? Any help is greatly appreciated! The relevant code from the table view controller is here: - (void)viewDidLoad { [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(modalOpened) name:@"ModalStartedOpening" object:nil]; [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(modalDismissed) name:@"ModalStartedClosing" object:nil]; [super viewDidLoad]; } - (void)modalOpened { [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:0.5]; [UIView setAnimationDelegate:self]; self.tableView.contentInset = UIEdgeInsetsMake(0, 0, 201, 0); self.tableView.scrollIndicatorInsets = UIEdgeInsetsMake(0, 0, 201, 0); [UIView commitAnimations]; } - (void)modalDismissed { [UIView beginAnimations:nil context:NULL]; [UIView setAnimationDuration:0.5]; [UIView setAnimationDelegate:self]; self.tableView.contentInset = UIEdgeInsetsMake(0, 0, 0, 0); self.tableView.scrollIndicatorInsets = UIEdgeInsetsMake(0, 0, 0, 0); [UIView commitAnimations]; }

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• Multiple checkbox values search javascript

  - by JV10

  I have a list of keywords, and I've created a checkbox for each. My template has a form wrapping the content, so I can't have a nested form around the checkbox list. How can I send the selected checkbox values to my search results page? The form that wraps the content doesn't have any actions or methods applied: <form id="BoostMasterForm" runat="server"> This the HTML markup of my checkbox list: <div class="checkboxes"> <ul> <li> <input type="checkbox" name="search" class="options" value="one"> <label>one</label> </li> <li> <input type="checkbox" name="search" class="options" value="two"> <label>two</label> </li> <li> <input type="checkbox" name="search" class="options" value="three"> <label>three</label> </li> </ul> <input type="submit" value="Submit"/> </div> How can I use javascript or jQuery to submit the values of the multiple checkbox selections and on submit action them to the following URL: '/imagery/image-search.aspx' The resulting URL for a search where option 1 and 3 are submitted should be: '/imagery/image-search.aspx?search=one%20three' I'm using this javascript that I found on another post, however I need it to append the form an the action and the method. My website is ASP, where this post is for a PHP site: Sending multiple checkbox options $('.options').click(function() { var selectedItems = new Array(); $(".checkboxes input:checkbox[name=search]:checked").each(function() {selectedItems.push($(this).val());}); var data = selectedItems.join('|'); $("#opts").val(data); }); If anyone can help, it'd be greatly appreciated. Cheers, JV

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• How to get Media Picker Field via proxy record of many-to-many in orchard

  - by Sergey Schipanov

  I need to access mediapickerfield in Widget view. This field is relative to 'ActionPart'. I have a problem, when I create many-to-many relationships to display my 'ActionPart' in the widget. When I mapped many-to-many I take an 'ActionPart' and but cannot access the mediapickerfield. Records classes public class ActionPartRecord : ContentPartRecord { public virtual string Text { get; set; } public virtual double Price { get; set; } public virtual int TextPosX { get; set; } public virtual int TextPosY { get; set; } public virtual String TextSale { get; set; } public virtual int Color { get; set; } } public class ActionListRecord { public virtual int Id { get; set; } public virtual ActionPartRecord ActionPartRecord { get; set; } public virtual ActionWidgetPartRecord ActionWidgetPartRecord { get; set; } } public class ActionWidgetPartRecord : ContentPartRecord { public ActionWidgetPartRecord() { ActionList = new List<ActionListRecord>(); } public virtual IList<ActionListRecord> ActionList { get; set; } } public class ActionWidgetPart : ContentPart<ActionWidgetPartRecord> { public IEnumerable<ActionPartRecord> ActionList { get { return Record.ActionList.Select(x => x.ActionPartRecord); } } } ActionPart class public class ActionPart : ContentPart<ActionPartRecord> { public String Text { get { return Record.Text; } set { Record.Text = value; } } /*other field*/ } Migrations public int Create() { SchemaBuilder.CreateTable("ActionPartRecord", table => table .ContentPartRecord() .Column<string>("Text") .Column<double>("Price") .Column<int>("TextPosX") .Column<int>("TextPosY") .Column<string>("TextSale") .Column<int>("Color") ); ContentDefinitionManager.AlterPartDefinition("ActionPart", builder => builder .WithField("BaseImage", fieldBuilder => fieldBuilder.OfType("MediaPickerField").WithDisplayName("Action Image")) .WithField("PatternImage", fieldBuilder => fieldBuilder.OfType("MediaPickerField").WithDisplayName("Pattern Image")) .WithField("TimeExp", fieldBuilder => fieldBuilder.OfType("DateTimeField").WithDisplayName("Expecting date")) .Attachable()); ContentDefinitionManager.AlterTypeDefinition("Action", cfg => cfg .WithPart("CommonPart") .WithPart("TitlePart") .WithPart("RoutePart") .WithPart("BodyPart") .WithPart("ActionPart") .Creatable() .Indexed()); SchemaBuilder.CreateTable("ActionListRecord", table => table .Column<int>("Id", column => column.PrimaryKey().Identity()) .Column<int>("ActionPartRecord_Id") .Column<int>("ActionWidgetPartRecord_Id") ); SchemaBuilder.CreateTable("ActionWidgetPartRecord", table => table .ContentPartRecord() ); ContentDefinitionManager.AlterPartDefinition( "ActionWidgetPart", builder => builder.Attachable()); ContentDefinitionManager.AlterTypeDefinition("ActionWidget", cfg => cfg .WithPart("ActionWidgetPart") .WithPart("WidgetPart") .WithPart("CommonPart") .WithSetting("Stereotype", "Widget")); return 1; } Driver Display method protected override DriverResult Display( ActionWidgetPart part, string displayType, dynamic shapeHelper) { return ContentShape("Parts_ActionWidget", () => shapeHelper.Parts_ActionWidget( ContentPart: part, ActionList: part.ActionList)); } Widget View @foreach (var action in Model.ActionList) { <div class="item"> *How to access BaseImage Field in this row* <div class="sale-pattern"></div> <div class="container"> <div class="carousel-caption"> <h1>@action.Text</h1> <h1 class="price">@action.Price</h1> </div> </div> </div> }

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• Implementing events to communicate between two processes - C

  - by Jamie Keeling

  Hello all! I have an application consisting of two windows, one communicates to the other and sends it a struct constaining two integers (In this case two rolls of a dice). I will be using events for the following circumstances: Process a sends data to process b, process b displays data Process a closes, in turn closing process b Process b closes a, in turn closing process a I have noticed that if the second process is constantly waiting for the first process to send data then the program will be just sat waiting, which is where the idea of implementing threads on each process occurred and I have started to implement this already. The problem i'm having is that I don't exactly have a lot of experience with threads and events so I'm not sure of the best way to actually implement what I want to do. Following is a small snippet of what I have so far in the producer application; Create thread: case IDM_FILE_ROLLDICE: { hDiceRoll = CreateThread( NULL, // lpThreadAttributes (default) 0, // dwStackSize (default) ThreadFunc(hMainWindow), // lpStartAddress NULL, // lpParameter 0, // dwCreationFlags &hDiceID // lpThreadId (returned by function) ); } break; The data being sent to the other process: DWORD WINAPI ThreadFunc(LPVOID passedHandle) { HANDLE hMainHandle = *((HANDLE*)passedHandle); WCHAR buffer[256]; LPCTSTR pBuf; LPVOID lpMsgBuf; LPVOID lpDisplayBuf; struct diceData storage; HANDLE hMapFile; DWORD dw; //Roll dice and store results in variable storage = RollDice(); hMapFile = CreateFileMapping( (HANDLE)0xFFFFFFFF, // use paging file NULL, // default security PAGE_READWRITE, // read/write access 0, // maximum object size (high-order DWORD) BUF_SIZE, // maximum object size (low-order DWORD) szName); // name of mapping object if (hMapFile == NULL) { dw = GetLastError(); MessageBox(hMainHandle,L"Could not create file mapping object",L"Error",MB_OK); return 1; } pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object FILE_MAP_ALL_ACCESS, // read/write permission 0, 0, BUF_SIZE); if (pBuf == NULL) { MessageBox(hMainHandle,L"Could not map view of file",L"Error",MB_OK); CloseHandle(hMapFile); return 1; } CopyMemory((PVOID)pBuf, &storage, (_tcslen(szMsg) * sizeof(TCHAR))); //_getch(); MessageBox(hMainHandle,L"Completed!",L"Success",MB_OK); UnmapViewOfFile(pBuf); return 0; } I'm trying to find out how I would integrate an event with the threaded code to signify to the other process that something has happened, I've seen an MSDN article on using events but it's just confused me if anything, I'm coming up on empty whilst searching on the internet too. Thanks for any help Edit: I can only use the Create/Set/Open methods for events, sorry for not mentioning it earlier.

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• A better UPDATE method in LINQ to SQL

  - by Refracted Paladin

  The below is a typical, for me, Update method in L2S. I am still fairly new to a lot of this(L2S & business app development) but this just FEELs wrong. Like there MUST be a smarter way of doing this. Unfortunately, I am having trouble visualizing it and am hoping someone can provide an example or point me in the right direction. To take a stab in the dark, would I have a Person Object that has all these fields as Properties? Then what, though? Is that redundant since L2S already mapped my Person Table to a Class? Is this just 'how it goes', that you eventually end up passing 30 parameters(or MORE) to an UPDATE statement at some point? For reference, this is a business app using C#, WinForms, .Net 3.5, and L2S over SQL 2005 Standard. Here is a typical Update Call for me. This is in a file(BLLConnect.cs) with other CRUD methods. Connect is the name of the DB that holds tblPerson When a user clicks save() this is what is eventually called with all of these fields having, potentially, been updated-- public static void UpdatePerson(int personID, string userID, string titleID, string firstName, string middleName, string lastName, string suffixID, string ssn, char gender, DateTime? birthDate, DateTime? deathDate, string driversLicenseNumber, string driversLicenseStateID, string primaryRaceID, string secondaryRaceID, bool hispanicOrigin, bool citizenFlag, bool veteranFlag, short ? residencyCountyID, short? responsibilityCountyID, string emailAddress, string maritalStatusID) { using (var context = ConnectDataContext.Create()) { var personToUpdate = (from person in context.tblPersons where person.PersonID == personID select person).Single(); personToUpdate.TitleID = titleID; personToUpdate.FirstName = firstName; personToUpdate.MiddleName = middleName; personToUpdate.LastName = lastName; personToUpdate.SuffixID = suffixID; personToUpdate.SSN = ssn; personToUpdate.Gender = gender; personToUpdate.BirthDate = birthDate; personToUpdate.DeathDate = deathDate; personToUpdate.DriversLicenseNumber = driversLicenseNumber; personToUpdate.DriversLicenseStateID = driversLicenseStateID; personToUpdate.PrimaryRaceID = primaryRaceID; personToUpdate.SecondaryRaceID = secondaryRaceID; personToUpdate.HispanicOriginFlag = hispanicOrigin; personToUpdate.CitizenFlag = citizenFlag; personToUpdate.VeteranFlag = veteranFlag; personToUpdate.ResidencyCountyID = residencyCountyID; personToUpdate.ResponsibilityCountyID = responsibilityCountyID; personToUpdate.EmailAddress = emailAddress; personToUpdate.MaritalStatusID = maritalStatusID; personToUpdate.UpdateUserID = userID; personToUpdate.UpdateDateTime = DateTime.Now; context.SubmitChanges(); } }

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• C++: Templates for static functions?

  - by Rosarch

  I have a static Utils class. I want certain methods to be templated, but not the entire class. How do I do this? This fails: #pragma once #include <string> using std::string; class Utils { private: template<class InputIterator, class Predicate> static set<char> findAll_if_rec(InputIterator begin, InputIterator end, Predicate pred, set<char> result); public: static void PrintLine(const string& line, int tabLevel = 0); static string getTabs(int tabLevel); template<class InputIterator, class Predicate> static set<char> Utils::findAll_if(InputIterator begin, InputIterator end, Predicate pred); }; Error: utils.h(10): error C2143: syntax error : missing ';' before '<' utils.h(10): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int utils.h(10): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int utils.h(10): error C2238: unexpected token(s) preceding ';' utils.h(10): error C2988: unrecognizable template declaration/definition utils.h(10): error C2059: syntax error : '<' What am I doing wrong? What is the correct syntax for this? Incidentally, I'd like to templatize the return value, too. So instead of: template<class InputIterator, class Predicate> static set<char> findAll_if_rec(InputIterator begin, InputIterator end, Predicate pred, set<char> result); I'd have: template<class return_t, class InputIterator, class Predicate> static return_t findAll_if_rec(InputIterator begin, InputIterator end, Predicate pred, set<char> result); How would I specify that: 1) return_t must be a set of some sort 2) InputIterator must be an iterator 3) InputIterator's type must work with return_t's type. Thanks.

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• How not to abort http response c#

  - by user194076

  I need to run several methods after sending file to a user for a download. What happens is that after I send a file to a user, response is aborted and I can no longer do anything after response.end(). for example, this is my sample code: Response.Clear(); Response.AddHeader("content-disposition", "attachment; filename=test.pdf"); Response.ContentType = "application/pdf"; byte[] a = System.Text.Encoding.UTF8.GetBytes("test"); Response.BinaryWrite(a); Response.End(); StartNextMethod(); Response.Redirect(URL); So, in this example StartNextMethod and Response.Redirect are not executing. What I tried is I created a separate handler(ashx) with the following code: public void ProcessRequest(HttpContext context) { context.Response.Clear(); context.Response.AddHeader("content-disposition", "attachment; filename=test.pdf"); context.Response.ContentType = "application/pdf"; byte[] a = System.Text.Encoding.UTF8.GetBytes("test"); context.Response.BinaryWrite(a); context.Response.End(); } and call it like this: Download d = new Download(); d.ProcessRequest(HttpContext.Current); StartNextMethod(); Response.Redirect(URL); but the same error happen. I've tryied to replace Response.End with CompleteRequest but it doesn't help. I guess the problem is that I'm using HttpContext.Current but should use a separate response stream. Is that correct? how do I do that in a separate method generically (Assume that I want my handler to accept byte array of data and content type and be downloadable from a separate response. I really do not want to use a separate page for a response. UPDATE I still didn't find a good solution. I'd like to do some actions after user has downloaded a file, but without using a separate page for a response\request thing.

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• Getting 404 when attempting to POST file to Google Cloud Storage from service account

  - by klactose

  I'm wondering if anyone can tell me the proper syntax & formatting for a service account to send a POST Object to bucket request? I'm attempting it programmatically using the HttpComponents library. I manage to get a token from my GoogleCredential, but every time I construct the POST request, I get: HTTP/1.1 403 Forbidden <?xml version='1.0' encoding='UTF-8'?><Error><Code>AccessDenied</Code><Message>Access denied.</Message><Detailsbucket-name</Details></Error The Google documentation that describes the request methods, mentions posting using html forms, but I'm hoping that wasn't suggesting the ONLY way to get the job done. I know that HttpComponents has a way to explicitly create form data by using UrlEncodedFormEntity, but it doesn't support multipart data. Which is why I went with using the MultipartEntity class. My code is below: MultipartEntity entity = new MultipartEntity( HttpMultipartMode.BROWSER_COMPATIBLE ); String token = credential.getAccessToken(); entity.addPart("Authorization", new StringBody("OAuth " + token)); String date = formatDate(new Date()); entity.addPart("Date", new StringBody(date)); entity.addPart("Content-Encoding", new StringBody("UTF-8")); entity.addPart("Content-Type", new StringBody("multipart/form-data")); entity.addPart("bucket", new StringBody(bucket)); entity.addPart("key", new StringBody("fileName")); entity.addPart("success_action_redirect", new StringBody("/storage")); File uploadFile = new File("pathToFile"); FileBody fileBody = new FileBody(uploadFile, "text/xml"); entity.addPart("file", fileBody); httppost.setEntity(entity); System.out.println("Posting URI = "+httppost.toString()); HttpResponse response = client.execute(httppost); HttpEntity resp_entity = response.getEntity(); As I mentioned, I am able to get an actual token, so I'm pretty sure the problem is in how I've formed the request as opposed to not being properly authenticated. Keep in mind: This is being performed by a service account. Which means that it does have Read/Write access Thanks for reading, and I appreciate any help!

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• Passing objects to a UITypeEditor

  - by Kath

  I am currently hoping to use a PropertyGrid to allow users to edit some of my classes, however I've hit a wall with passing objects to the UITypeEditor(s) they use. When the user presses the drop down I want to show a listbox of already loaded textures to choose from, if they want to use a texture the application hasn't loaded yet they can click a button to choose one from a file dialog. In case I make no sense here a mock of the form: . My problem: To fill the listbox I need access to the class that manages the list of resources from the UITypeEditor. Now I've solved this problem for my own classes by giving them a reference on creation to their managing object. In the UITypeEditor I then use that reference to access what I need. However I can't do this for classes I haven't written, such as the XNA Texture2D class. Here are what the classes I'm using look like: class StaticGeometryChunk { // Geometry data to draw with. Contains a reference to its managing // class for use in its UITypeEditor. public GeometryData { get; set; } .... } class Material { // These are XNA classes. I can't just add a reference to its managing // class (I think?). public Texture2D Texture1 { get; set; } public Texture2D Texture2 { get; set; } .... } I've been looking at my options and they seem to be: Make the managing classes static. I don't really want to do this. There are several managing classes as each resource is loaded differently. There are also classes that need to be created before these and are passed in. Make the managing classes singletons. I don't really want to do this either. It seems like a quick and dirty way to "hide" the problem instead of "solve" it. I also might want the option of having several managing classes in the future which the singletons eliminate. Create a wrapper class which holds the reference to a managing class and its target (such as the XNA Texture2D). This is currently what I'm thinking of doing. Its would be quite simple and quick to do but something about it nags me but I don't know what. Any thoughts on the above or other methods to pass what I need into the UITypeEditor? Thank you for reading.

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• Updating UISearchDisplayController with Core Data results using GCD

  - by Brian Halpin

  I'm having trouble displaying the results from Core Data in my UISearchDisplayController when I implement GCD. Without it, it works, but obviously blocks the UI. In my SearchTableViewController I have the following two methods: - (BOOL)searchDisplayController:(UISearchDisplayController *)controller shouldReloadTableForSearchString:(NSString *)searchString { // Tell the table data source to reload when text changes [self filterContentForSearchText:searchString]; // Return YES to cause the search result table view to be reloaded. return YES; } // Update the filtered array based on the search text -(void)filterContentForSearchText:(NSString*)searchText { // Remove all objects from the filtered search array [self.filteredLocationsArray removeAllObjects]; NSPredicate *predicate = [CoreDataMaster predicateForLocationUsingSearchText:@"Limerick"]; CoreDataMaster *coreDataMaster = [[CoreDataMaster alloc] init]; // Filter the array using NSPredicate self.filteredLocationsArray = [NSMutableArray arrayWithArray: [coreDataMaster fetchResultsFromCoreDataEntity:@"City" UsingPredicate:predicate]]; } You can probably guess that my problem is with returning the array from [coreDataMaster fetchResultsFromCoreDataEntity]. Below is the method: - (NSArray *)fetchResultsFromCoreDataEntity:(NSString *)entity UsingPredicate:(NSPredicate *)predicate { NSMutableArray *fetchedResults = [[NSMutableArray alloc] init]; dispatch_queue_t coreDataQueue = dispatch_queue_create("com.coredata.queue", DISPATCH_QUEUE_SERIAL); dispatch_async(coreDataQueue, ^{ NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; NSEntityDescription *entityDescription = [NSEntityDescription entityForName:entity inManagedObjectContext:self.managedObjectContext]; NSSortDescriptor *nameSort = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES]; NSArray *sortDescriptors = [NSArray arrayWithObjects:nameSort, nil]; [fetchRequest setEntity:entityDescription]; [fetchRequest setSortDescriptors:sortDescriptors]; // Check if predicate is set if (predicate) { [fetchRequest setPredicate:predicate]; } NSError *error = nil; NSArray *fetchedManagedObjects = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error]; for (City *city in fetchedManagedObjects) { [fetchedResults addObject:city]; } NSDictionary *userInfo = [NSDictionary dictionaryWithObject:[NSArray arrayWithArray:fetchedResults] forKey:@"results"]; [[NSNotificationCenter defaultCenter] postNotificationName:@"fetchResultsComplete" object:nil userInfo:userInfo]; }); return [NSArray arrayWithArray:fetchedResults]; } So the thread hasn't finished executing by the time it returns the results to self.filteredLocationsArray. I've tried added a NSNotification which passes the NSDictionary to this method: - (void)updateSearchResults:(NSNotification *)notification { NSDictionary *userInfo = notification.userInfo; NSArray *array = [userInfo objectForKey:@"results"]; self.filteredLocationsArray = [NSMutableArray arrayWithArray:array]; [self.tableView reloadData]; } I've also tried refreshing the searchViewController like [self.searchDisplayController.searchResultsTableView reloadData]; but to no avail. I'd really appreciate it if someone could point me in the right direction and show me where I might be going wrong. Thanks

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• How to perform add/update of a model object that contains EntitySet

  - by David Liddle

  I have a similar concept to the SO questions/tags scenario however am trying to decide the best way of implementation. Tables Questions, QuestionTags and Tags Questions QuestionTags Tags --------- ------------ ---- QID QID TID QName TID TName When adding/updating a question I have 2 textboxes. The important part is a single textbox that allows users to enter in multiple Tags separated by spaces. I am using Linq2Sql so the Questions model has an EntitySet of QuestionTags with then link to Tags. My question is regarding the adding/updating of Questions (part 1), and also how to best show QuestionTags for a Question (part 2). Part 1 Before performing an add/update, my service layer needs to deal with 3 scenarios before passing to their respective repositories. Insert Tags that do not already exist Insert/Update Question Insert QuestionTags - when updating need to remove existing QuestionTags Here is my code below however started to get into a bit of a muddle. I've created extension methods on my repositories to get Tags WithNames etc. public void Add(Question q, string tags) { var tagList = tags.Split(new string[] { " " }, StringSplitOptions.RemoveEmptyEntries).ToList(); using (DB.TransactionScope ts = new DB.TransactionScope()) { var existingTags = TagsRepository.Get() .WithName(tagList) .ToList(); var newTags = (from t in tagList select new Tag { TName = t }).Except(existingTags, new TagsComparer()).ToList(); TagsRepository.Add(newTags); //need to insert QuestionTags QuestionsRepository.Add(q); ts.Complete(); } } Part 2 My second question is, when displaying a list of Questions how is it best to show their QuestionTags? For example, I have an Index view that shows a list of Questions in a table. One of the columns shows an image and when the user hovers over it shows the list of Tags. My current implementation is to create a custom ViewModel and show a List of QuestionIndexViewModel in the View. QuestionIndexViewModel { Question Question { get; set; } string Tags { get; set; } } However, this seems a bit clumsy and quite a few DB calls. public ViewResult Index() { var model= new List<QuestionIndexViewModel>(); //make a call to get a list of questions //foreach question make a call to get their QuestionTags, //to be able to get their Tag names and then join them //to form a single string. return View(model); } Also, just for test purposes using SQL Profiler, I decided to iterate through the QuestionTags entity set of a Question in my ViewModel however nothing was picked up in Profiler? What would be the reason for this?

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• Parallel Task Library WaitAny Design

  - by colithium

  I've just begun to explore the PTL and have a design question. My Scenario: I have a list of URLs that each refer to an image. I want each image to be downloaded in parallel. As soon as at least one image is downloaded, I want to execute a method that does something with the downloaded image. That method should NOT be parallelized -- it should be serial. I think the following will work but I'm not sure if this is the right way to do it. Because I have separate classes for collecting the images and for doing "something" with the collected images, I end up passing around an array of Tasks which seems wrong since it exposes the inner workings of how images are retrieved. But I don't know a way around it. In reality there is more to both of these methods but that's not important for this. Just know that they really shouldn't be lumped into one large method that both retrieves and does something with the image. Task<Image>[] downloadTasks = collector.RetrieveImages(listOfURLs); for (int i = 0; i < listOfURLs.Count; i++) { //Wait for any of the remaining downloads to complete int completedIndex = Task<Image>.WaitAny(downloadTasks); Image completedImage = downloadTasks[completedIndex].Result; //Now do something with the image (this "something" must happen serially) } /////////////////////////////////////////////////// public Task<Image>[] RetrieveImages(List<string> urls) { Task<Image>[] tasks = new Task<Image>[urls.Count]; int index = 0; foreach (string url in urls) { string lambdaVar = url; //Required... Bleh tasks[index] = Task<Image>.Factory.StartNew(() => { using (WebClient client = new WebClient()) { //TODO: Replace with live image locations string fileName = String.Format("{0}.png", i); client.DownloadFile(lambdaVar, Path.Combine(Application.StartupPath, fileName)); } return Image.FromFile(Path.Combine(Application.StartupPath, fileName)); }, TaskCreationOptions.LongRunning | TaskCreationOptions.AttachedToParent); index++; } return tasks; }

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