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  • What is the root directory OR how do I set the directory in DotNetZip

    - by Chris
    where does DotNetZip get it's root directory for saving. All the save examples don't show the directory. My goal is to recurse a folder and subfolders. In each folder I want to zip all the files into one zip and delete the source files. private void CopyFolder(string srcPath, string dstPath) { if (!Directory.Exists(dstPath)) Directory.CreateDirectory(dstPath); string[] files = Directory.GetFiles(srcPath); string msg; string zipFileName; using (ZipFile z = new ZipFile(Path.Combine(srcPath,String.Format("Archive{0:yyyyMMdd}.zip", DateTime.Now)))) { z.ReadProgress += new EventHandler<ReadProgressEventArgs>(z_ReadProgress); foreach (string file in files) { FileInfo fi = new FileInfo(file); AddLog(String.Format("Adding {0}", file)); z.AddFile(file); } //z.Save(Path.Combine(srcPath, String.Format("Archive{0:yyyyMMdd}.zip", DateTime.Now))); z.Save(); if (deleteSource) { foreach (string file in files) { File.Delete(file); } } zipFileName = z.Name; } if (!compressOnly) File.Copy(Path.Combine(srcPath,zipFileName), Path.Combine(dstPath, Path.GetFileName(zipFileName))); string[] folders = Directory.GetDirectories(sourcePath); foreach (string folder in folders) { string name = Path.GetFileName(folder); string dest = Path.Combine(dstPath, name); Console.WriteLine(ln); log.Add(ln); msg = String.Format("{3}{4}Start Copy: {0}{4}Directory: {1}{4}To: {2}", DateTime.Now.ToString("G"), name, dest, ln, Environment.NewLine); AddLog(msg); if (recurseFolders) CopyFolder(folder, dest); msg = String.Format("Copied Directory: {0}{4}To: {1}\nAt: {2}{3}", folder, dest, DateTime.Now.ToString("G"), Environment.NewLine); AddLog(msg); } }

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  • Bash script to log in over SSH

    - by user1042928
    Sorry if this seems like a dumb question but I am just learning bash scripting. For a school project we need to code an RTX that runs in Unix. It runs as a process in terminal and takes in user input and then prints it to the screen. I want to write a bash script to test that it can respond to lots of quick user input without overflowing or failing. My main problem is that once the RTX starts the bash script will stop on that line until the RTX terminates and only then print the loop to the terminal (instead of printing it to the RTX prompt as I intend it to). I have tried running the RTX in the background but that didn't work. I need to find a way to redirect input to the RTX while it is still running with a bash script. Google searches didn't come up with examples that I understood/could adapt. Any help is appreciated. #!/bin/bash # declare STRING variable STRING="RTX Worked =D" #Start the rtx in a new process, stuck on this line until rtx terminates. ./main #Somehow redirect io to the rtx. for i in `seq 1 100`; do echo $i echo " \n" done echo $STRING

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  • C# Help with a basic pedagogic example of a BackGroundWorker process populating a DataGridView

    - by Roger
    Scenario: I have a windows form that holds a DataGridWiew with 3 pre-defined columns. I have 3 variables declared outside the function and assigned to inside the function. I have a function that enumerates stuff and puts it in the 3 columns, line by line: string VARIABLE1; string VARIABLE2; string VARIABLE3; private void FunctionEnumerateStuff() { foreach (StuffObject STUFF in StuffCollection) { VARIABLE1 = STUFF.SubStuff1.ToString(); VARIABLE2 = STUFF.SubStuff2.ToString(); VARIABLE3 = STUFF.SubStuff3.ToString(); DatagridWiew1.Rows.Add(VALUE1, VALUE2, VALUE3); } } What I want to do, is to execute this function from a BackGroundWorker process, so that the GUI of the application will be smooth and responsive. I have read up on backgroundworkers but I am having trouble relating, because all examples seems to be of entirely different scenarios and most of them are overwelmingly complex. San some helpful pedagogic soul help me and others with a very basic example of how to get this to work in the simplest way possible. Thanks.

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  • Are there some cases where Python threads can safely manipulate shared state?

    - by erikg
    Some discussion in another question has encouraged me to to better understand cases where locking is required in multithreaded Python programs. Per this article on threading in Python, I have several solid, testable examples of pitfalls that can occur when multiple threads access shared state. The example race condition provided on this page involves races between threads reading and manipulating a shared variable stored in a dictionary. I think the case for a race here is very obvious, and fortunately is eminently testable. However, I have been unable to evoke a race condition with atomic operations such as list appends or variable increments. This test exhaustively attempts to demonstrate such a race: from threading import Thread, Lock import operator def contains_all_ints(l, n): l.sort() for i in xrange(0, n): if l[i] != i: return False return True def test(ntests): results = [] threads = [] def lockless_append(i): results.append(i) for i in xrange(0, ntests): threads.append(Thread(target=lockless_append, args=(i,))) threads[i].start() for i in xrange(0, ntests): threads[i].join() if len(results) != ntests or not contains_all_ints(results, ntests): return False else: return True for i in range(0,100): if test(100000): print "OK", i else: print "appending to a list without locks *is* unsafe" exit() I have run the test above without failure (100x 100k multithreaded appends). Can anyone get it to fail? Is there another class of object which can be made to misbehave via atomic, incremental, modification by threads? Do these implicitly 'atomic' semantics apply to other operations in Python? Is this directly related to the GIL?

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  • process of connecting RTP with SIP via SDP & land lines

    - by TacB0sS
    Hello to everyone, I have a problem with starting a media session and to combine it with my SIP client. I've designed a recursive SIP client that reuse the same request template to send the next requests to server, according to the acceptable sequences noted in the RFC's, and examples that I read. as far as I could tell the SIP part is working fine registers to server invites, and authenticates. I didn't complete any calls to clients yet because of the content header needs to be filled up (which I didn't yet so I get a 503 from the server which is OK I guess). for a long time I didn't know where to start with the media session, and slowly learned how to use the JMF and I've constructed an object that handles RTP transmitting, now I'm standing at the cross road, on the one hand I have my SIP signaling but it needs the SDP content header to complete the invite, and on the other I have the RTP which is knows how to p2p. For me to complete my design I require your help with the following questions: Is there an easy//a simple//an implemented way to convert the Audio/Video format from the JMF into SDP media headers? or even a generator that I would input all the parameters for the content header, and it would generate a content header fast, or do I have to implement this myself? Once I've finished constructing the SDK and the SIP is up and running and I get an OK response from the server (after ringing and all), how do I start the media session? do I connect p2p according to caller details I send in the SIP invite? If 2 is correct, then how does a connection to land lines would be? does land lines knows that once they send an OK back to server they listen/start RTP session on a specific port? Or did I get everything wrong? :-/ I really appreciate any help I could I get, I looked every where for answers but they are not clear, they ignore question 2 as if it was an obvious thing, but for me it just isn't. Thank in advance, Adam Zehavi.

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  • Which languages support *recursive* function literals / anonymous functions?

    - by Hugh Allen
    It seems quite a few mainstream languages support function literals these days. They are also called anonymous functions, but I don't care if they have a name. The important thing is that a function literal is an expression which yields a function which hasn't already been defined elsewhere, so for example in C, &printf doesn't count. EDIT to add: if you have a genuine function literal expression <exp>, you should be able to pass it to a function f(<exp>) or immediately apply it to an argument, ie. <exp>(5). I'm curious which languages let you write function literals which are recursive. Wikipedia's "anonymous recursion" article doesn't give any programming examples. Let's use the recursive factorial function as the example. Here are the ones I know: JavaScript / ECMAScript can do it with callee: function(n){if (n<2) {return 1;} else {return n * arguments.callee(n-1);}} it's easy in languages with letrec, eg Haskell (which calls it let): let fac x = if x<2 then 1 else fac (x-1) * x in fac and there are equivalents in Lisp and Scheme. Note that the binding of fac is local to the expression, so the whole expression is in fact an anonymous function. Are there any others?

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  • How to cast sockaddr_storage and avoid breaking strict-aliasing rules

    - by sinoth
    I'm using Beej's Guide to Networking and came across an aliasing issue. He proposes a function to return either the IPv4 or IPv6 address of a particular struct: 1 void *get_in_addr( struct sockaddr *sa ) 2 { 3 if (sa->sa_family == AF_INET) 4 return &(((struct sockaddr_in*)sa)->sin_addr); 5 else 6 return &(((struct sockaddr_in6*)sa)->sin6_addr); 7 } This causes GCC to spit out a strict-aliasing error for sa on line 3. As I understand it, it is because I call this function like so: struct sockaddr_storage their_addr; ... inet_ntop(their_addr.ss_family, get_in_addr((struct sockaddr *)&their_addr), connection_name, sizeof connection_name); I'm guessing the aliasing has to do with the fact that the their_addr variable is of type sockaddr_storage and another pointer of a differing type points to the same memory. Is the best way to get around this sticking sockaddr_storage, sockaddr_in, and sockaddr_in6 into a union? It seems like this should be well worn territory in networking, I just can't find any good examples with best practices. Also, if anyone can explain exactly where the aliasing issue takes place, I'd much appreciate it.

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  • Please help me with database connection types in Windows.

    - by Hamish Grubijan
    Sorry for a badly-phrased question. I have a requirement coming from a non-technical person that I need to make sense of. I am basically told: "Here use 'Driver={SQL Server};Server=SERVERNAME\INSTANCENAME;Database=DATABASENAME;Uid=UNAME;Pwd=PASSWORD;'; and here use Server=SERVERNAME\INSTANCENAME;Database=DATABASENAME;Uid=UNAME;Pwd=PASSWORD;';. I am getting no additional help here. While this seems to miraculously fix a bug, I want to understand what is it that I am changing, so I can leave a proper comment for the next developer, plus I can structure the code and name variables differently, depending on the meaning of the change. The work revolves around ASP.net, reporting, SQL Server 2008. Please give me some examples about when you would use one connection string over another. Feel free to edit the question if you can see a way to improve it. When can you lose a 'Driver={SQL Server};? Thank you. EDIT: SQL Server 2008 is the target database, but other can be used ... or maybe will be used in the future.

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  • How to bind a table in a dataset to a WPF datagrid in C# and XAML

    - by Jim Thomas
    I have been searching to hours for something very simple: bind a WPF datagrid to a datatable in order to see the columns at design-time. I can’t get any of the examples to work for me. Here is the C# code to populate the datatable InfoWork inside the dataset info: info = new Info(); InfoTableAdapters.InfoWorkTableAdapter adapter = new InfoTableAdapters.InfoWorkTableAdapter(); adapter.Fill(info.InfoWork); The problem is no matter how I declare ‘info’ or ‘infoWork’ Visual Studio/XAML can’t find it. I have tried: <Window.Resources> <ObjectDataProvider x:Key="infoWork" ObjectType="{x:Type local:info}" /> </Window.Resources> I have also tried this example from wpf.codeplex, but XAML doesn’t even like the “local:” keyword! <Window.Resources> <local:info x:Key="infoWork"/> </Window.Resources> There are really two main questions here: 1) How do I declare the table InfoWork in C# so that XAML can see it? I tried declaring it Public in the window class that XAML exists in with no success. 2) How do I declare the windows resource in XAML, specifcally the datatable inside the dataset? Out of curiosity, is there a reason that ItemsSource just doesn't show up as a property that be set in the properties design window?

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  • JQGRID Master detail on different pages

    - by dennisg
    Hello, I need some help on next things. I was trying to do next few things. I have one grid_test.php (that creates jqgrid) and index_grid.php (just to display grid.php). jQGrid in grid.php have custom button named 'Prikazi'. I want the user to select one row from that grid and when press custom button 'Prikazi' to redirect to another page to show subgrid (and to pass parameter which is the id of the selected row). Subgrid is in the file detail_test.php and also I have file called index_detail.php (for displaying the file detail_test.php with jqgrid). These php files communicate by passing parameter id_reda (or id) that is id of the selected row in grid_test.php. I have tried many ways to achieve that but I wasn't able. Subgrid php file (detail_test.php) receives that parameter but when I add that to sql statement in subgrid file it shows next error: Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[42000]: Syntax error or access violation: 1064 You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'LIMIT 0, 0' at line 16' in C:\Zend\Apache2\htdocs\jqSuitePHP3811SourceRadna\php\jqGridPdo.php:62 I really don't know what am I doing wrong. Maybe the passing of parameter is wrong and maybe subgrid can't create colModel properly. Or it has something to do with sql statements. Actually my work was based on one of your examples masterdetail, but I wanted to have master grid on one page and when user clicks custom button, goes to another page with detail grid. You can see my example on next page: http://pljevlja.org/grid/index_test.php. And all my php files are here: -http://pljevlja.org/grid/TXT.zip<- Thanks in advance,

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  • Interactive Web Collaboration Platform

    - by user1477586
    I am currently unsatisfied with most, if not all, web-based collaboration tools I've ever used. Examples of what I'm considering a "web-based collaboration tool" are TWiki, WebEx, etc. What I have in mind of developing is to develop my own. The target "market" is for software/hardware developers who will likely be working on separate projects linked by a common goal. Example: You work at a company who is designing a brand new printer. So, one man is working on the ink cartridge, another on the paper feed, one on the circuitry of the printer and one more is working on the drivers. What I would like to make (unless it already exists) is a website that, upon loading, presents the user with a web that has each project within it's own bubble, graphically. These bubbles would all be linked to the central bubble of "[Company Name]". Upon selecting an individual bubble the browser would focus and zoom in on that project bubble and expand more information (in bullets or with more affiliated bubbles) about subprojects, progress, setbacks, etc. Then, at a terminal "node" (i.e. a bubble with no sub-bubbles) a selection would then load a page with information relevant to that node. That's a lot of monologue. In short, I want to know how I might approach this. My background is with algorithmic use of Python and C++. I've never done interactive web design like this; though, I have gone through the W3C tutorials on HTML4/5. I'm willing to learn a new language I'm just wondering which language/set of languages seem(s) most appropriate for this project. Thanks, world, for imparting your knowledge to me. An example of what the start page might look like is:

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  • Merging: hg/git vs. svn

    - by stmax
    I often read that hg (and git and...) are better at merging than svn but I have never seen practical examples of where hg/git can merge something where svn fails (or where svn needs manual intervention). Could you post a few step-by-step lists of branch/modify/commit/...-operations that show where svn would fail while hg/git happily moves on? Practical, not highly exceptional cases please... Some background: we have a few dozen developers working on projects using svn, with each project (or group of similar projects) in its own repo. We know how to apply release- and feature-branches so we don't run into problems very often (i.e. we've been there, but we've learned to overcome joel's problems of "one programmer causing trauma to the whole team" or "needing six developers for two weeks to reintegrate a branch"). We have release-branches that are very stable and only used to apply bugfixes. We have trunks that should be stable enough to be able to create a release within one week. And we have feature-branches that single developers or groups of developers can work on. Yes, they are deleted after reintegration so they don't clutter up the repository. ;) So I'm still trying to find the advantages of hg/git over svn. I'd love to get some hands-on experience, but there aren't any bigger projects we could move to hg/git yet, so I'm stuck with playing with small artifical projects that only contain a few made up files. And I'm looking for a few cases where you can feel the impressive power of hg/git, since so far I have often read about them but failed to find them myself.

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  • NSTableView Drag and Drop not working

    - by macatomy
    Hi, I'm trying to set up very basic drag and drop for my NSTableView. The table view has a single column (with a custom cell). The column is bound to an NSArrayController, and the array controller's content array is bound to an NSArray on my controller object. The data displays fine in the table. I connected the dataSource and delegate outlets of the table view to my controller object, and then implemented these methods: - (BOOL)tableView:(NSTableView *)aTableView writeRowsWithIndexes:(NSIndexSet *)rowIndexes toPasteboard:(NSPasteboard *)pboard { NSLog(@"dragging"); return YES; } - (NSDragOperation)tableView:(NSTableView*)tv validateDrop:(id <NSDraggingInfo>)info proposedRow:(NSInteger)row proposedDropOperation:(NSTableViewDropOperation)op { return NSDragOperationEvery; } - (BOOL)tableView:(NSTableView *)aTableView acceptDrop:(id <NSDraggingInfo>)info row:(NSInteger)row dropOperation:(NSTableViewDropOperation)operation { return YES; } I also registered the drag types in -awakeFromNib: #define MyDragType @"MyDragType" - (void)awakeFromNib { [super awakeFromNib]; [_myTable registerForDraggedTypes:[NSArray arrayWithObjects:MyDragType, nil]]; } The problem is that the -tableView:writeRowsWithIndexes:toPasteboard: method is never called. I've looked at a bunch of examples and I can't figure out anything I'm doing wrong. Could the problem be that I'm using a custom cell? Is there something I'm supposed to override in the cell subclass to enable this functionality? EDIT: Confirmed. Switching the custom cell for a regular NSTextFieldCell made dragging work. Now, how do I make drag and drop work with my custom cell?

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  • Proper use of the IDisposable interface

    - by cwick
    I know from reading the MSDN documentation that the "primary" use of the IDisposable interface is to clean up unmanaged resources http://msdn.microsoft.com/en-us/library/system.idisposable.aspx. To me, "unmanaged" means things like database connections, sockets, window handles, etc. But, I've seen code where the Dispose method is implemented to free managed resources, which seems redundant to me, since the garbage collector should take care of that for you. For example: public class MyCollection : IDisposable { private List<String> _theList = new List<String>(); private Dictionary<String, Point> _theDict = new Dictionary<String, Point>(); // Die, you gravy sucking pig dog! public void Dispose() { _theList.clear(); _theDict.clear(); _theList = null; _theDict = null; } My question is, does this make the garbage collector free memory used by MyCollection any faster than it normally would? edit: So far people have posted some good examples of using IDisposable to clean up unmanaged resources such as database connections and bitmaps. But suppose that _theList in the above code contained a million strings, and you wanted to free that memory now, rather than waiting for the garbage collector. Would the above code accomplish that?

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  • dynamically created radiobuttonlist

    - by Janet
    Have a master page. The content page has a list with hyperlinks containing request variables. You click on one of the links to go to the page containing the radiobuttonlist (maybe). First problem: When I get to the new page, I use one of the variables to determine whether to add a radiobuttonlist to a placeholder on the page. I tried to do it in page)_load but then couldn't get the values selected. When I played around doing it in preInit, the first time the page is there, I can't get to the page's controls. (Object reference not set to an instance of an object.) I think it has something to do with the MasterPage and page content? The controls aren't instantiated until later? (using vb by the way) Second problem: Say I get that to work, once I hit a button, can I still access the passed request variable to determine the selected item in the radiobuttonlist? Protected Sub Page_PreInit(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.PreInit 'get sessions for concurrent Dim Master As New MasterPage Master = Me.Master Dim myContent As ContentPlaceHolder = CType(Page.Master.FindControl("ContentPlaceHolder1"), ContentPlaceHolder) If Request("str") = "1" Then Dim myList As dsSql = New dsSql() ''''instantiate the function to get dataset Dim ds As New Data.DataSet ds = myList.dsConSessionTimes(Request("eid")) If ds.Tables("conSessionTimes").Rows.Count > 0 Then Dim conY As Integer = 1 CType(myContent.FindControl("lblSidCount"), Label).Text = ds.Tables("conSessionTimes").Rows.Count.ToString Sorry to be so needy - but maybe someone could direct me to a page with examples? Maybe seeing it would help it make sense? Thanks....JB

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  • How to connect remote EJB module from application client

    - by Zeck
    Hi guys, I have a EJB module in remote Glassfish server and application client in my computer. I want to connect from the application client to the remote EJB. Here is the my EJB interface: @Remote public interface BookEJBRemote { public String getTitle(); } Here is the my ejb: @Stateless public class BookEJB implements BookEJBRemote { @Override public String getTitle() { return "Twenty Thousand Leagues Under the Sea"; } } I have several questions : Can I use Dependency Injection in the remote application client to connect to the ejb? If so what can i do to achieve this. Do i need to configure in the sun-ejb-jar.xml and sun-application-client.xml? In other words, if i use DI like @EJB MyEJBRemote ejb; How application client container know what ejb to be injected? Where should i specify the information? How can i run the application client? I tried to run package-appclient in the glassfish server to get appclient.jar and copy it to my computer. Then i type appclient.jar -client myAppClient.jar . It didn't work. How do i point the target server? if i cannot use DI in the client then i guess i have to use JNDI lookup. Do i need to configure jndi name in sun-ejb-jar.xml or in the sun-application-client.xml? No matter how i try i never manage to run application client ? Can you guys put some working example? And thank you for every advises and examples?

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  • JAAS and WebLogic 10.3: Granting specific codebase permissions to a JAR bundled within an EAR

    - by Jason
    Here's my scenario: I have a JAR within the APP-INF/lib of my EAR, to be deployed within WebLogic 10g Release 3 against which I wish to grant specific permissions. e.g., grant codebase "file:/c:/somedir/my.jar" { permission java.net.SocketPermission "*:-","accept,connect,listen, resolve"; permission java.net.SocketPermission "localhost:-","accept,connect,listen,resolve"; permission java.net.SocketPermission "127.0.0.1:-","accept,connect,listen,resolve"; permission java.net.SocketPermission "230.0.0.1:-","accept,connect,listen,resolve"; permission java.util.PropertyPermission "*", "read,write"; permission java.lang.RuntimePermission "*"; permission java.io.FilePermission "<<ALL FILES>>","read,write,delete"; permission javax.security.auth.AuthPermission "*"; permission java.security.SecurityPermission "*"; }; Questions: Where is the best place to define this grant - in the java.policy of the JRE, WL server's weblogic.policy, or within a XML packaged within the EAR How do I define the codebase URL to the JAR? The examples I have seen have an explicit reference to the JAR on the file system, however I am deploying the JAR packaged up within an EAR. Thanks!

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  • Need Advice on designing ATL inproc Server (dll) that serves as both a soure and a sink of events.

    - by Andrew
    Hi, I need to design an ATL inproc server that besides exposing methods and properties, also can fire events (source) and serve as a sink for a third party COM control that fires events. I would assume that this is a fairly common requirement. I can also foresee several "gotchas" that I would like to read up on before commencing the design. My questions/concerns are: Can someone point me to an example? Which threading model to use? Should I have a seperate COM object for the sink? Should I, and how do I, protect certain memory. For example, my server will receive data from the third party control. It will save this, and in some cases, fire an event to interested clients. The interested clients will request the data through a standard method or property. I did try to research this myself. I can find many examples of COM servers that are soures, and some that are sinks, but never both. The only post I did find was this: http://www.generation-nt.com/us/atl-control-an-event-source-sink-help-9098542.html Which strongly advocates putting the sink on a seperate COM object. Any leads, tutorials or ideas would be much appreciated. Thanks, Andrew

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  • conceptual question : what do performSelectorOnMainThread do?

    - by hib
    Hello all, I just come across this strange situation . I was using the technique of lazy image loading from apple examples . when I was used the class in my application it gave me topic to learn but don't what was actually happening there . So here goes the scenario : I think everybody has seen the apple lazytableimagesloading . I was reloading my table on finishing the parsing of data : - (void)didFinishParsing:(NSMutableArray *)appList { self.upcomingArray = [NSMutableArray arrayWithArray:loadedApps]; // we are finished with the queue and our ParseOperation [self.upcomingTableView reloadData]; self.queue = nil; // we are finished with the queue and our ParseOperation } but as a result the the connection was not starting and images were not loading . when I completely copy the lazyimageloading and I replaced the above code with the following code it works fine - (void)didFinishParsing:(NSMutableArray *)appList { [self performSelectorOnMainThread:@selector(handleLoadedApps:) withObject:appList waitUntilDone:NO]; self.queue = nil; // we are finished with the queue and our ParseOperation } So I want to know what is the concept behind this . Please let me know if you can not understand the question or details are not enough because I desperately want to know why it is like this ?

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  • Getter and Setter vs. Builder strategy

    - by Extrakun
    I was reading a JavaWorld's article on Getter and Setter where the basic premise is that getters expose internal content of an object, hence tightening coupling, and go on to provide examples using builder objects. I was rather leery of abolishing getter/setter but on second reading of the article, see to quite like the idea. However, sometimes I just need one cruical element of an entity class, such as the user's id and writing one whole class just to extract that cruical element seems like overkill. It also implies that for different view, a different type of importer/exporter must be implemented (or the whole data of the class to be exported out, thus resulting in waste). Usually I tend towards filtering the result of a getter - for example, if I need to output the price of a product in different currency, I would code it as: return CurrencyOutput::convertTo($product->price(), 'USD'); This is with the understanding that the raw output of a getter is not necessary the final result to be pushed onto a screen or a database. Is getter/setter really as bad as it is protrayed to be? When should one adopt a builder strategy, or a 'get the result and filter it' approach? How do you avoid having a class needing to know about every other objects if you are not using getter/setter?

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  • Are lambda expressions/delegates in C# "pure", or can they be?

    - by Bob
    I recently asked about functional programs having no side effects, and learned what this means for making parallelized tasks trivial. Specifically, that "pure" functions make this trivial as they have no side effects. I've also recently been looking into LINQ and lambda expressions as I've run across examples many times here on StackOverflow involving enumeration. That got me to wondering if parallelizing an enumeration or loop can be "easier" in C# now. Are lambda expressions "pure" enough to pull off trivial parallelizing? Maybe it depends on what you're doing with the expression, but can they be pure enough? Would something like this be theoretically possible/trivial in C#?: Break the loop into chunks Run a thread to loop through each chunk Run a function that does something with the value from the current loop position of each thread For instance, say I had a bunch of objects in a game loop (as I am developing a game and was thinking about the possibility of multiple threads) and had to do something with each of them every frame, would the above be trivial to pull off? Looking at IEnumerable it seems it only keeps track of the current position, so I'm not sure I could use the normal generic collections to break the enumeration into "chunks". Sorry about this question. I used bullets above instead of pseudo-code because I don't even know enough to write pseudo-code off the top of my head. My .NET knowledge has been purely simple business stuff and I'm new to delegates and threads, etc. I mainly want to know if the above approach is good for pursuing, and if delegates/lambdas don't have to be worried about when it comes to their parallelization.

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  • How do i refactor this code by using Action<t> or Func<t> delegates

    - by user330612
    I have a sample program, which needs to execute 3 methods in a particular order. And after executing each method, should do error handling. Now i did this in a normal fashion, w/o using delegates like this. class Program { public static void Main() { MyTest(); } private static bool MyTest() { bool result = true; int m = 2; int temp = 0; try { temp = Function1(m); } catch (Exception e) { Console.WriteLine("Caught exception for function1" + e.Message); result = false; } try { Function2(temp); } catch (Exception e) { Console.WriteLine("Caught exception for function2" + e.Message); result = false; } try { Function3(temp); } catch (Exception e) { Console.WriteLine("Caught exception for function3" + e.Message); result = false; } return result; } public static int Function1(int x) { Console.WriteLine("Sum is calculated"); return x + x; } public static int Function2(int x) { Console.WriteLine("Difference is calculated "); return (x - x); } public static int Function3(int x) { return x * x; } } As you can see, this code looks ugly w/ so many try catch loops, which are all doing the same thing...so i decided that i can use delegates to refactor this code so that Try Catch can be all shoved into one method so that it looks neat. I was looking at some examples online and couldnt figure our if i shud use Action or Func delegates for this. Both look similar but im unable to get a clear idea how to implement this. Any help is gr8ly appreciated. I'm using .NET 4.0, so im allowed to use anonymous methods n lambda expressions also for this Thanks

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  • Atomic Instructions and Variable Update visibility

    - by dsimcha
    On most common platforms (the most important being x86; I understand that some platforms have extremely difficult memory models that provide almost no guarantees useful for multithreading, but I don't care about rare counter-examples), is the following code safe? Thread 1: someVariable = doStuff(); atomicSet(stuffDoneFlag, 1); Thread 2: while(!atomicRead(stuffDoneFlag)) {} // Wait for stuffDoneFlag to be set. doMoreStuff(someVariable); Assuming standard, reasonable implementations of atomic ops: Is Thread 1's assignment to someVariable guaranteed to complete before atomicSet() is called? Is Thread 2 guaranteed to see the assignment to someVariable before calling doMoreStuff() provided it reads stuffDoneFlag atomically? Edits: The implementation of atomic ops I'm using contains the x86 LOCK instruction in each operation, if that helps. Assume stuffDoneFlag is properly cleared somehow. How isn't important. This is a very simplified example. I created it this way so that you wouldn't have to understand the whole context of the problem to answer it. I know it's not efficient.

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  • best practice for boolean REST results

    - by Andrew Patterson
    I have a resource /system/resource And I wish to ask the system a boolean question about the resource that can't be answered by processing on the client (i.e I can't just GET the resource and look through the actual resource data - it requires some processing on the backend using data not available to the client). eg /system/resource/related/otherresourcename I want this is either return true or false. Does anyone have any best practice examples for this type of interaction? Possibilities that come to my mind: use of HTTP status code, no returned body (smells wrong) return plain text string (True, False, 1, 0) - Not sure what string values are appropriate to use, and furthermore this seems to be ignoring the Accept media type and always returning plain text come up with a boolean object for each of my support media types and return the appropriate type (a JSON document with a single boolean result, an XML document with a single boolean field). However this seems unwieldy. I don't particularly want to get into a long discussion about the true meaning of a RESTful system etc - I have used the word REST in the title because it best expresses the general flavour of system I am designing (even if perhaps I am tending more towards RPC over the web rather than true REST). However, if someone has some thoughts on how a true RESTful system avoids this problem entirely I would be happy to hear them.

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  • How to get SQL Function run a different query and return value from either query?

    - by RoguePlanetoid
    I need a function, but cannot seem to get it quite right, I have looked at examples here and elsewhere and cannot seem to get this just right, I need an optional item to be included in my query, I have this query (which works): SELECT TOP 100 PERCENT SKU, Description, LEN(CONVERT(VARCHAR (1000),Description)) AS LenDesc FROM tblItem WHERE Title = @Title AND Manufacturer = @Manufacturer ORDER BY LenDesc DESC This works within a Function, however the Manufacturer is Optional for this search - which is to find the description of a similar item, if none is present, the other query is: SELECT TOP 100 PERCENT SKU, Description, LEN(CONVERT(VARCHAR (1000),Description)) AS LenDesc FROM tblItem WHERE Title = @Title ORDER BY LenDesc DESC Which is missing the Manufacturer, how to I get my function to use either query based on the Manufacturer Value being present or not. The reason is I will have a function which first checks an SKU for a Description, if it is not present - it uses this method to get a Description from a Similar Product, then updates the product being added with the similar product's description. Here is the function so far: ALTER FUNCTION [dbo].[GetDescriptionByTitleManufacturer] ( @Title varchar(400), @Manufacturer varchar(160) ) RETURNS TABLE AS RETURN ( SELECT TOP 100 PERCENT SKU, Description, LEN(CONVERT(VARCHAR (1000),Description)) AS LenDesc FROM tblItem WHERE Title = @Title AND Manufacturer = @Manufacturer ORDER BY LenDesc DESC ) I've tried adding BEGINs and IF...ELSEs but get errors or syntax problems each way I try it, I want to be able to do something like this pseudo-function (which does not work): ALTER FUNCTION [dbo].[GetDescriptionByTitleManufacturer] ( @Title varchar(400), @Manufacturer varchar(160) ) RETURNS TABLE AS BEGIN IF (@Manufacturer = Null) RETURN ( SELECT TOP 100 PERCENT SKU, Description, LEN(CONVERT(VARCHAR (1000),Description)) AS LenDesc FROM tblItem WHERE Title = @Title ORDER BY LenDesc DESC ) ELSE RETURN ( SELECT TOP 100 PERCENT SKU, Description, LEN(CONVERT(VARCHAR (1000),Description)) AS LenDesc FROM tblItem WHERE Title = @Title AND Manufacturer = @Manufacturer ORDER BY LenDesc DESC ) END

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