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• Detect when a UITableView is being reordered

  - by Mike Weller

  I have a UITableView backed by an NSFetchedResultsController which may trigger updates at any time. If the user is currently reordering rows, applying these updates will cause an exception because the table view has temporarily taken over and you get an error like Invalid update: invalid number of rows in section [...] How can I detect when the user has started moving a cell so I can delay updates caused by the fetched results controller? There don't seem to be any table view delegate methods to detect this. This delegate method: - (NSIndexPath *)tableView:(UITableView *)tableView targetIndexPathForMoveFromRowAtIndexPath:(NSIndexPath *)sourceIndexPath toProposedIndexPath:(NSIndexPath *)proposedDestinationIndexPath { Doesn't get called when the user initially detaches the first cell, only when they actually move it somewhere else.

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• Log RuntimeException thrown from thread created by Spring via the @Async annotation

  - by Eugen

  I'm having some difficulty logging RuntimeException from a thread. My system is: Java 7 (b118), Spring 3.0.5. The threads are not created by hand, but via Spring's @Async annotation, which creates it's own executor behind the scenes, so I don't really have the option of overriding any methods of the thread, FutureTask or anything low level. So my question is if Spring has any support or if there are any best practices for handling (logging) these type of exceptions? Any suggestions are appreciated. Thanks.

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• Is Lightweight Code Generation (LCG) dead?

  - by Greg Beech

  In the .NET 2.0-3.5 frameworks, LCG (aka the DynamicMethod class) was a decent way to emit lightweight methods at runtime when no class structure was needed to support them. In .NET 4.0, expression trees now support statements and blocks, and as such appear to provide sufficient functionality to build just about any functionality you could require from such a method, and can be constructed in a much easier and safer way than directly emitting CIL op-codes. (This statement is borne from today's experimentation of converting some of our most complex LCG code to use expression tree building and compilation instead.) So is there any reason why one would use LCG in any new code? Is there anything it can do that expression trees cannot? Or is it now a 'dead' piece of functionality?

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• Designing constructors around type erasure in Java

  - by Internet Friend

  Yesterday, I was designing a Java class which I wanted to be initalized with Lists of various generic types: TheClass(List<String> list) { ... } TheClass(List<OtherType> list) { ... } This will not compile, as the constructors have the same erasure. I just went with factory methods differentiated by their names instead: public static TheClass createWithStrings(List<String> list) public static TheClass createWithOtherTypes(List<OtherType> list) This is less than optimal, as there isn't a single obvious location where all the different options for creating instances are available. I tried to search for better design ideas, but found surprisingly few results. What other patterns exist for designing around this problem?

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• Show facebook status stream of a dedicated person on a website

  - by Pascal

  Hi all, I've been stomping at this all day :( I want to display a status feed of both twitter and facebook on my website. For twitter, this is not a problem, as my account is public, I can easily get the feed. Facebook however, is a whole different story! I can't seem to find an easy way to just get my last status updates and display it on my website. The code I currently have, needs authentication of the visitor, and I don't want that! This is my current code: $facebook = new Facebook($api_key, $secret); $stream = $facebook->api_client->fql_query("SELECT message,source,time FROM status WHERE uid = $user_id LIMIT 6"); I've seen several possible solutions, including the RSS feed, but as Facebook keeps changing the way their site works, none of the previous methods I've seen (including those from as late as januari) currently work! Is there anybody who can provide me with a currently working solution to this (simple?) problem?

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• Select a data template by item type programatically in WPF

  - by Michael Stoll

  Hi all, unfortunately the WPF ToolbarTray does not support binding to a collection of ToolbarViewModels (Correct me, if I'm wrong). Thus I want to create the Toolbars programmatically. So there are two tasks, which I don't know how to do: Select the data template based on the item type. Instantiate the data template as toolbar Both should do the same as WPF does, when we use ItemsControl with an enumerable content and empty template. I used reflector to anaylse what WPF does. Task 1 is done by FrameworkElement.FindTemplateResourceInternal, but this is internal, and I couldn't find any public methods to acomplish the task. Of course one could enumerate all resources and match the data template data type property, but this seems sub-optimal. Who know's how to acomplish these tasks?

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• C++ Asymptotic Profiling

  - by Travis

  I have a performance issue where I suspect one standard C library function is taking too long and causing my entire system (suite of processes) to basically "hiccup". Sure enough if I comment out the library function call, the hiccup goes away. This prompted me to investigate what standard methods there are to prove this type of thing? What would be the best practice for testing a function to see if it causes an entire system to hang for a sec (causing other processes to be momentarily starved)? I would at least like to definitively correlate the function being called and the visible freeze. Thanks

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• C++ visitor pattern handling templated string types?

  - by Steve the Plant

  I'm trying to use the visitor pattern to serialize the contents of objects. However one snag I'm hitting is when I'm visiting strings. My strings are of a templated type, similar to STL's basic_string. So something like: basic_string<char_type, memory_allocator, other_possible_stuff> \\ many variations possible! Since I can have very many different templated string types, I can't go and add them to my visitor interface. It would be ridiculous. But I can't add templates to my VisitString method because C++ prevents using templates parameters in virtual methods. So what are my options to work around this?

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• What's the proper way to use sqlite on the iPhone?

  - by Elliot Chen

  Hi, Experts: Can you please give some suggestions on sqlite using on the iPhone? Within my application, I use a sqlite DB to store all local data. Two methods can be used to retrieve those data during running time. 1, Load all the data into memory at initialization stage. (More memory used, less DB open/close operation needed) 2, Read corresponding records when necessary, free the occupied memory after using. (Good habit for memory using, but much DB open/close operations needs). I prefer to use method 2, but not sure whether too many DB opening/closing operations could affect app's efficiency. Or do you think I can 'upgrade' method 2 by opening DB when app launches and closing DB when app quits? Thanks for your suggestions very much!

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• Load a bitmap from file in RGB format (without alpha)

  - by Robert

  Hi, i simply want to load a .BMP file and get the Bitmap object in 24bit RGB format (or 32bit in RGB format). All methods I tried return a Bitmap/Image object with PixelFormat = Format32bppArgb. Even if of course BMPs don't have alpha. new Bitmap(System.Drawing.Image.FromFile(fileName, true)); new Bitmap(fileName); I currently solve the problem by copying the first object to another in memory bitmap at 24bit RBG. Is there a single method to do it? Thanks

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• ASP.NET: How can I properly redirect requests with 404 errors?

  - by Adrian Grigore

  Hi, I'd like my ASP.NET MVC application to redirect failed requests to matching action methods of a certain controller. This works fine on my development machine running Windows 7, but not on my production machine running Windows 2008 R2. I set up my web.config as follows: <customErrors mode="On" defaultRedirect="/Error/ServerError/500"> <error statusCode="403" redirect="/Error/AccessDenied" /> <error statusCode="404" redirect="/Error/FileNotFound" /> </customErrors> This customErrors section works fine on both of my machines (production and development) for 500 Internal Server errors. It also works fine for 404 errors on my development machine. However, it does not properly redirect 404 errors on the production machine. Instead of /Error/FileNotFound, I get the standard 404 page that comes with IIS 7. What could be the problem here?

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• NET Framework Validation Library

  - by Kane

  As I see it most applications have a requirement for some form of validation and a number of fantastic free offerings are available (I.E., Fluent Validation, Validation Block, Spring, Castle Windsor, etc). My question is why does the .NET Framework not include any inbuilt validation libraries? I am aware the .NET Framework allows a developer the ability to build their own validation libraries/methods/etc. and anything provided as part of the .NET Framework would not always meet everyone’s needs. But surely something could have been included? ASP.NET has a minimal set of validators but these have not really been extended since .NET 2.0 was released.

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• Import module stored in a cStringIO data structure vs. physical disk file

  - by Malcolm

  Is there a way to import a Python module stored in a cStringIO data structure vs. physical disk file? It looks like "imp.load_compiled(name, pathname[, file])" is what I need, but the description of this method (and similar methods) has the following disclaimer: Quote: "The file argument is the byte-compiled code file, open for reading in binary mode, from the beginning. It must currently be a real file object, not a user-defined class emulating a file." [1] I tried using a cStringIO object vs. a real file object, but the help documentation is correct - only a real file object can be used. Any ideas on why these modules would impose such a restriction or is this just an historical artifact? Are there any techniques I can use to avoid this physical file requirement? Thanks, Malcolm [1] http://docs.python.org/library/imp.html#imp.load_module

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• Is this an UITableView -beginUpdates documentation error?

  - by mystify

  I can't wrap my head around what they tried to say here in the docs for -beginUpdate: Call this method if you want subsequent insertions, deletion, and selection operations (for example, cellForRowAtIndexPath: and indexPathsForVisibleRows) to be animated simultaneously. Let's see... cellForRowAtIndexPath: and indexPathsForVisibleRows are both GETTER methods. They do not update anything and do not change anything. So why should I call -beginUpdates before calling these? And what's animated regarding these? Well, nothing, huh? Just want to make sure this is really an error in the docs and I didn't miss something.

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• Using Routing helpers in a Rake task

  - by trobrock

  I have a rake task that sends out the next 'x' invitations to join a beta it uses this code: desc "This will send out the next batch of invites for the beta" task :send_invites => :environment do limit = ENV['limit'] c = 0 invitation = Invitation.all(:conditions => { :sent_at => nil, :sender_id => nil }, :limit => limit).each do |i| Mailer.deliver_invitation(i, register_url(i.token)) c.increment! end puts "Sent #{c} invitations." end I need to pass in the 'register_url' to the Mailer in order for the link to show up in the email, but since this is running from a rake task and not from a request it does not have a access to the helper methods. What is the best way of achieving this?

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• Autorelease for CGMutablePathRef?

  - by huggie

  Hi, I am developing for iphone. I want to creating a mutable path via CGPathCreateMutable(), and I want to return it out of the function which creates it. I'm suppose to call a CGPathRelease() when I'm done with it. But since I'm returning it I wish to autorelease it. Since Quartz path is a C code (and doesn't look like an objective C object), is it correct that I cannot call autorelease on it? Edit: For others who stumble upon this question, the below advise is for C functions returning Core foundation objects only. For objective C methods returning Core foundation objects, see http://stackoverflow.com/questions/2901942/ownership-regarding-to-returned-quartz-objects

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• How can I add a field with an array value to my Perl object?

  - by superstar

  What's the difference between these two constructors in perl? 1) sub new { my $class = shift; my $self = {}; $self->{firstName} = undef; $self->{lastName} = undef; $self->{PEERS} = []; bless ($self, $class); return $self; } 2) sub new { my $class = shift; my $self = { _firstName => shift, _lastName => shift, _ssn => shift, }; bless $self, $class; return $self; } I am using the second one so far, but I need to implement the PEERS array in the second one? How do I do it with the second constructor and how can we use get and set methods on those array variables?

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• Resetting Objects vs. Constructing New Objects

  - by byronh

  Is it considered better practice and/or more efficient to create a 'reset' function for a particular object that clears/defaults all the necessary member variables to allow for further operations, or to simply construct a new object from outside? I've seen both methods employed a lot, but I can't decide which one is better. Of course, for classes that represent database connections, you'd have to use a reset method rather than constructing a new one resulting in needless connecting/disconnecting, but I'm talking more in terms of abstraction classes. Can anyone give me some real-world examples of when to use each method? In my particular case I'm thinking mostly in terms of ORM or the Model in MVC. For example, if I would want to retrieve a bunch of database objects for display and modify them in one operation.

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• Core Data and BOOL setup

  - by John Valen

  I am working on an app that uses Core Data as its backend for managing SQLite records. I have everything working with strings and numbers, but have just tried adding BOOL fields and can't seem to get things to work. In the .xcdatamodel, I have added a field to my object called isCurrentlyForSale which is not Optional, not Transient, and not Indexed. The attribute's type is set to Boolean with default value NO. When I created the class files from the data model, the boilerplate code added for this property in the .h header was: @property (nonatomic, retain) NSNumber * isCurrentlyForSale; along with the @dynamic isCurrentlyForSale; in the .m implementation file. I've always worked with booleans as simple BOOLs. I've read that I could use NSNumber's numberWithBool and boolValue methods, but this seems like an aweful lot of extra code for something so simple. Can the @property in the header be changed to a simple BOOL? If so is there anything to watch out for? Thanks -John

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• In JSF, how to handle repeating over a list that mutates

  - by Jon

  Hello, In a JSF page, I am iterating over a list of items provided by a session-scoped backing bean. The list needs to be kept up-to-date, so it is replaced with a fresh list every X minutes by a thread (in a thread-safe way). On my page, for each item I provide some text inputs and an "Update" button. If the list is refreshed before I hit "Update", the update does not happen (which is my problem). I happen to be using a4j:repeat, but I think this could also apply to other methods of iteration, including using dataTables. Any thoughts on how I can do this in a non-hackish way? Thanks!

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• C# implementation of PushbackInputStream

  - by Mark Heath

  I need a C# implementation of Java's PushbackInputStream. I have made my own very basic one, but I wondered if there was a well tested and decently performing version already available somewhere. As it happens I always push back the same bytes I read so really it just needs to be able to reposition backwards, buffering up to a number of bytes I specify. (like Java's BufferedInputStream with the mark and reset methods). Update: I should add that I can't simply reposition the stream as CanSeek may be false. (e.g. when the input steam is a NetworkStream)

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• REST - why we need million urls and different HTTP request?

  - by Andre

  I asked this question. But I still don't understand why we need to utilize different HTTP requests: DELETE/PUT/POST/GET in order to build nice API Wouldn't it be a lot simpler to pass all information in request parameters and have a SINGLE ENTRY-POINT for your api?: GET www.example.com/api?id=1&method=delete&returnformat=JSON GET www.example.com/api?id=1&method=delete&returnformat=XML or POST www.example.com/api {post data: id=1&method=delete&returnformat=JSON} POST www.example.com/api {post data: id=1&method=delete&returnformat=XML} and then - we can handle all methods and data internally without the need for hundreds of urls... how would you call this type of API - It's not REST apparently, it's not SOAP. then - what is it? UPDATE I'm not proposing any new standards here. I merely asking a question in order to better understand why web services work the way they work.

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• How to increase query speed without using full-text search?

  - by andre matos

  This is my simple query; By searching selectnothing I'm sure I'll have no hits. SELECT nome_t FROM myTable WHERE nome_t ILIKE '%selectnothing%'; This is the EXPLAIN ANALYZE VERBOSE Seq Scan on myTable (cost=0.00..15259.04 rows=37 width=29) (actual time=2153.061..2153.061 rows=0 loops=1) Output: nome_t Filter: (nome_t ~~* '%selectnothing%'::text) Total runtime: 2153.116 ms myTable has around 350k rows and the table definition is something like: CREATE TABLE myTable ( nome_t text NOT NULL, ) I have an index on nome_t as stated below: CREATE INDEX idx_m_nome_t ON myTable USING btree (nome_t); Although this is clearly a good candidate for Fulltext search I would like to rule that option out for now. This query is meant to be run from a web application and currently it's taking around 2 seconds which is obviously too much; Is there anything I can do, like using other index methods, to improve the speed of this query?

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• Programmatic Website Screen Shots

  - by Ian

  I'm checking into the available methods for programmatically taking screenshots of an arbitrary website. For example, Facebook: http://clicktoverify.truste.com/pvr.php?page=validate&url=www.facebook.com&sealid=102 Salesforce.com: http://clicktoverify.truste.com/pvr.php?page=validate&companyName=Salesforce.com,%20Inc.&sealid=102&internal=true On that page you'll see they have a screenshot of the referenced site. What are my options for getting these kinds of screenshots in an automated fashion? I'm primarily working with PHP, but am open to all suggestions. Thanks!

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• Passing objects by reference or not in C#

  - by Piku

  Suppose I have a class like this: public class ThingManager { List<SomeClass> ItemList; public void AddToList (SomeClass Item) { ItemList.Add(Item); } public void ProcessListItems() { // go through list one item at a time, get item from list, // modify item according to class' purpose } } Assume "SomeClass" is a fairly large class containing methods and members that are quite complex (List<s and arrays, for example) and that there may be a large quantity of them, so not copying vast amounts of data around the program is important. Should the "AddToList" method have "ref" in it or not? And why? It's like trying to learn pointers in C all over again ;-) (which is probably why I am getting confused, I'm trying to relate these to pointers. In C it'd be "SomeClass *Item" and a list of "SomeClass *" variables)

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