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  • Calling a void async. - Event based pattern, or another method?

    - by alex
    I have a class that basically stores files in amazon s3. Here is what it looks like (simplified) public class S3FileStore { public void PutFile(string ID, Stream content) { //do stuff } } In my client app, I want to be able to call: var s3 = new() S3FileStore(); s3.PutFile ("myId", File.OpenRead(@"C:\myFile1")); s3.PutFile ("myId", File.OpenRead(@"C:\myFile2")); s3.PutFile ("myId", File.OpenRead(@"C:\myFile3")); I want this to be an asynchronous operation - I want the S3FileStore to handle this (i don't want my caller to have to execute PutFile asynchronously so to speak) but, i want to be able to trap exceptions / tell if the operation completed for each file. I've looked at event based async calls, especially this: http://blogs.windowsclient.net/rendle/archive/2008/11/04/functional-shortcuts-2-event-based-asynchronous-pattern.aspx However, I can't see how to call my PutFile (void) method? Are there any better examples?

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  • jQuery get value from checked element with a given name

    - by Travis Leleu
    I've got an input like so: I'd like to use jQuery to grab that element, and add the function call foo() to the change event. Currently I can get it done, but there are two hacks involved. My (working) code: $(":input[name*=myfield]").change( function( $(":input[name*=myfield]") ) { foo(); }); )}; There are two hacks in there I'd like to eliminate. Keeping in mind that the input names are multidimensional arrays, how can I use the :input[name=somename], versus [name*=someone]? I'd imagine it's faster using an exact name rather than *=, but I can't get the escape sequence correct for the brackets on the multidimensional arrays. Can I chain the call together so that I don't have to select the element twice? Is the standard practice for that to select the HTML element into a var, then use that var? Or can I chain it together? Thanks for the help. Still working on getting my footing in JS/JQ.

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  • How can I consolidate deferred/delayed calls in Objective-C ?

    - by thrusty
    I'd like to ensure that certain maintenance tasks are executed "eventually". For example, after I detect that some resources might no longer be used in a cache, I might call: [self performSelector:@selector(cleanupCache) withObject:nil afterDelay:0.5]; However, there might be numerous places where I detect this, and I don't want to be calling cleanupCache continuously. I'd like to consolidate multiple calls to cleanupCache so that we only periodically get ONE call to cleanupCache. Here's what I've come up with do to this-- is this the best way? [NSObject cancelPreviousPerformRequestsWithTarget:self selector:@selector(cleanupCache) object:nil]; [self performSelector:@selector(cleanupCache) withObject:nil afterDelay:0.5];

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  • Is it possible to change the pane locations in Chrome Developer Tools?

    - by T.J. Crowder
    When debugging browser-based apps using Google Chrome's Developer Tools, is there a way to change the locations of the various panes? E.g., the Watch Expressions, the Call Stack, the code pane, etc.? The defaults are okay (console at bottom, code pane upper left, a column of Watch Expressions, Call Stack, Scope Vars, etc. in the upper right), but I'd rather swap things around a bit of it's possible. There doesn't seem to be anything to grab (other than for sizing) and I haven't found a way in my searching so far, but there are (still) some things about Chrome's options that aren't ... well-advertised in the UI, shall we say :-), especially around developer tools.

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  • Can I destroy a class instance even if there are still references?

    - by DR
    For debugging reasons I want to destroy a class instance which still as references. Is that possible? It doesn't have to be elegant or stable, because this'll never end up in production code. To clarify: Public Sub Main Dim o as MyClass Set o = New MyClass //o is created, one reference DestroyObject o //Class_Terminate is called and the object destroyed //Further code, not using o End Sub //Possible runtime error here (don't care) Is that possible? One way would be to call IUnknown::Release to manually decrease the reference count, but how do I now how often I must call it?

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  • how have defined connection within function for pdo communication with DB

    - by Scarface
    hey guys I just started trying to convert my query structure to PDO and I have come across a weird problem. When I call a pdo query connection within a function and the connection is included outside the function, the connection becomes undefined. Anyone know what I am doing wrong here? I was just playing with it, my example is below. include("includes/connection.php"); function query(){ $user='user'; $id='100'; $sql = 'SELECT * FROM users'; $stmt = $conn->prepare($sql); $result=$stmt->execute(array($user, $id)); echo $count=$stmt->rowCount(); if (!$result || $stmt->rowCount()>=1){ echo 'balls'; } // now iterate over the result as if we obtained // the $stmt in a call to PDO::query() while($r = $stmt->fetch(PDO::FETCH_ASSOC)) { echo "$r[username] $r[id] \n"; } } query();

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  • car and cdr in Scheme are driving me crazy ...

    - by kristian Roger
    Hi Im facing a problem with the car and cdr functions for example: first I defined a list called it x (define x (a (bc) d ( (ef) g ) )) so x now is equal to (a (bc) d ( (ef) g ) ) now for example I need to get the g from this list using only car and cdr (!! noshortcuts as caddr cddr !!) the correct answer is: (car(cdr(car(cdr(cdr(cdr x)))))) BUT how ? :-( I work according to the rules (the car gives the head of list and cdr gives the tail) and instead of getting the answer above I keep reaching wrong answers. Can any one help me in understanding this ... give me step or a way to solve it step by step Thanks in advance. I'm really sick of Scheme.

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  • Why first arg to execve() must be path to executable

    - by EBM
    I understand that execve() and family require the first argument of its argument array to be the same as the executable that is also pointed to by its first argument. That is, in this: execve(prog, args, env); args[0] will usually be the same as prog. But I can't seem to find information as to why this is. I also understand that executables (er, at least shell scripts) always have their calling path as the first argument when running, but I would think that the shell would do the work to put it there, and execve() would just call the executable using the path given in its first argument ("prog" from above), then passing the argument array ("args" from above) as one would on the command line.... i.e., I don't call scripts on the command line with a duplicate executable path in the args list.... /bin/ls /bin/ls /home/john Can someone explain?

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  • Python json memory bloat

    - by Anoop
    import json import time from itertools import count def keygen(size): for i in count(1): s = str(i) yield '0' * (size - len(s)) + str(s) def jsontest(num): keys = keygen(20) kvjson = json.dumps(dict((keys.next(), '0' * 200) for i in range(num))) kvpairs = json.loads(kvjson) del kvpairs # Not required. Just to check if it makes any difference print 'load completed' jsontest(500000) while 1: time.sleep(1) Linux top indicates that the python process holds ~450Mb of RAM after completion of 'jsontest' function. If the call to 'json.loads' is omitted then this issue is not observed. A gc.collect after this function execution does releases the memory. Looks like the memory is not held in any caches or python's internal memory allocator as explicit call to gc.collect is releasing memory. Is this happening because the threshold for garbage collection (700, 10, 10) was never reached ? I did put some code after jsontest to simulate threshold. But it didn't help.

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  • Design pattern for mouse interaction

    - by mike
    I need some opinions on what is the "ideal" design pattern for a general mouse interaction. Here the simplified problem. I have a small 3d program (QT and openGL) and I use the mouse for interaction. Every interaction is normally not only a single function call, it is mostly performed by up to 3 function calls (initiate, perform, finalize). For example, camera rotation: here the initial function call will deliver the current first mouse position, whereas the performing function calls will update the camera etc. However, for only a couple of interactions, hardcoding these (inside MousePressEvent, MouseReleaseEvent MouseMoveEvent or MouseWheelEvent etc) is not a big deal, but if I think about a more advanced program (e.g 20 or more interactions) then a proper design is needed. Therefore, how would you design such a interactions inside QT. I hope I made my problem clear enough, otherwise don't bother complain :-) Thanks

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  • How bad is opening and closing a SQL connection for several times? What is the exact effect?

    - by Eren
    For example, I need to fill lots of DataTables with SQLDataAdapter's Fill() method: DataAdapter1.Fill(DataTable1); DataAdapter2.Fill(DataTable2); DataAdapter3.Fill(DataTable3); DataAdapter4.Fill(DataTable4); DataAdapter5.Fill(DataTable5); .... .... Even all the dataadapter objects use the same SQLConnection, each Fill method will open and close the connection unless the connection state is already open before the method call. What I want to know is how does unnecessarily opening and closing SQLConnections affect the performance of the application. How much does it need to scale to see the bad effects of this problem (100,000s of concurrent users?). In a mid-size website (daily 50000 users) does it worth bothering and searching for all the Fill() calls, keeping them together in the code and opening the connection before any Fill() call and closing afterwards?

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  • Passing variables from SQL proceedure to PHP

    - by Sam Corbet
    I am trying to create an sql proceedure that will return the results back to the php page. I want to be able to call the procedure as follows from the php call procedure_name($var1) which will run this script: -- --------------------------------------------------------------------------------- -- pUIGetCliStmtGenFlag -- -- This procedure returns the status of the Trading Period: -- -- --------------------------------------------------------------------------------- drop procedure if exists pUIGetCliStmtGenFlag; delimiter // create procedure pUIGetCliStmtGenFlag( IN pTradingPeriodMonth DATE ) MODIFIES SQL DATA COMMENT 'Checks if the TP has been closed' begin SELECT trading_period_month, dt_end, amt_traded_system_ccy FROM ca_trading_period WHERE trading_period_month=$var1 -- If amt_traded_system_ccy is NULL give the TP an open status otherwise mark as closed IF amt_traded_system_ccy is NULL $tpstatus='open' ELSE $tpstatus='closed' end; // delimiter ; I then want to be able to use $tpstatus in the rest of the php script. I know this is simple but this is completely new to me and I cant find the correct method

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  • How do I measure the time elapsed when calling a WCF Webservice?

    - by Manuel R.
    We want to track the time taken by a web service call between a client and the server. This time should not include the time taken by the server to process the request. The idea is that we want to see how much time of a web service call is lost due to the actual transfer trough the network. Does WCF already offer something in this direction? Of course I could just add a timer on the client and subtract the server processing time but that wouldn't be very elegant.

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  • How can I receive messages over http without MSMQ

    - by pduncan
    I need a reliable messaging framework that runs over http/https (due to client security requirements) and that doesn't use MSMQ (because some clients will use Windows XP Home). The clients only need to be able to receive messages, not send them. We already have a message queue on the server for each user, and the receivers have been getting messages by connecting to an HttpHandler on the server and getting a Stream from WebResponse.GetResponseStream() We keep this stream open, and pull messages off of it using Stream.Read(). This MOSTLY works, but Stream.Read() is a blocking call, and we can't reliably interrupt it. We need to be able to stop and start the receiver without losing messages, but the old stream often hangs around, even after we call Thread.Abort on its thread. Any suggestions?

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  • Is there an optimal way to render images in cocoa? Im using setNeedsDisplay

    - by Edward An
    Currently, any time I manually move a UIImage (via handling the touchesMoved event) the last thing I call in that event is [self setNeedsDisplay], which effectively redraws the entire view. My images are also being animated, so every time a frame of animation changes, i have to call setNeedsDisplay. I find this to be horrific since I don't expect iphone/cocoa to be able to perform such frequent screen redraws very quickly. Is there an optimal, more efficient way that I could be doing this? Perhaps somehow telling cocoa to update only a particular region of the screen (the rect region of the image)?

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  • [R] multiple functions in one R script

    - by Philipp
    Hi, I guess it's a stupid question, but I don't get it :-( I wrote an R script, which creates heatmaps out of xls files. I am calling this R script with a Perl system call and pass over all the arguments. This all works fine. Now I wanted to make the R script less confusing by writing different functions in the R script, for example: args <- commandArgs(TRUE) parsexls <- function(filepath) { data <- read.xls(...) assign("data", data, globalenv()) } reorder <- function(var) { data <- data[order...] assign("data", data, globalenv()) } When I want to call the functions with parsexls(args[1]) reorder(args[2]) nothing happens. But when I place the parsexls(args[1]) in the script between the two functions shown above, the file is parsed correctly! The reorder(args[2]) seems never to be read. Any ideas what I am doing wrong? Phil

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  • RAII: Initializing data member in const method

    - by Thomas Matthews
    In RAII, resources are not initialized until they are accessed. However, many access methods are declared constant. I need to call a mutable (non-const) function to initialize a data member. Example: Loading from a data base struct MyClass { int get_value(void) const; private: void load_from_database(void); // Loads the data member from database. int m_value; }; int MyClass :: get_value(void) const { static bool value_initialized(false); if (!value_initialized) { // The compiler complains about this call because // the method is non-const and called from a const // method. load_from_database(); } return m_value; } My primitive solution is to declare the data member as mutable. I would rather not do this, because it suggests that other methods can change the member. How would I cast the load_from_database() statement to get rid of the compiler errors?

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  • Cannot import SQLite with Python 2.6

    - by David McLaughlin
    I'm running Python 2.6 on Unix and when I run the interactive prompt (SQLite is supposed to be preinstalled) I get: [root@idev htdocs]# python Python 2.6 (r26:66714, Oct 23 2008, 16:25:34) [GCC 3.2.2 20030222 (Red Hat Linux 3.2.2-5)] on linux2 Type "help", "copyright", "credits" or "license" for more information. >>> import sqlite Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: No module named sqlite >>> import sqlite Traceback (most recent call last): File "<stdin>", line 1, in <module> ImportError: No module named sqlite >>> How do I resolve this?

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  • How to programatically set cell.textLabel.text from a different view?

    - by Andy
    I've got a view controller, call it VC1, that's a table view. When I tap a cell in the table view, I am presented with a new view controller, call it VC2, which is a short list of choices. After making a choice, I want to dismiss VC2 and set the cell.textLabel.text property of the VC1 cell I originally tapped to the value I selected in VC2. Conceptually speaking, what is the proper way to do this? I've tried a handful of different approaches, but all of them seem wonky at best, and only one of them actually worked - although it was the most cumbersome of all, passing references to both view controllers and table view cells and all kinds of things. It just feels like I'm making a mountain out of what is probably a mole hill. This is such a common paradigm that I find it hard to believe there's not a simple method for doing it. Thanks in advance for any input you can offer.

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  • LuaInterface - how to register overloaded methods?

    - by JeffreySadeli
    Hello world! I'm trying to integrate Lua to my C# app when I hit a little snag. I was hoping someone with more expertise could help point me to the right direction. Let's say I have the following C# methods: public void MyMethod(int foo) { ... } public void MyMethod(int foo, int bar) { ... } I would like to register it to my Lua script environment so that I can do something like this: -- call method with one param MyMethod(123) -- call method with two params MyMethod(123, 456) I tried RegisterFunction("MyMethod", this, this.GetType().GetMethod("MyMethod")) but it reasonably complains about ambiguous match. Any ideas?

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  • RIA Services and multiple/dynamic "Include" strategies

    - by user326526
    As an example, assume the following simple model: public class Order { public List<LineItem> LineItems { get; set; } public List<Fee> Fees { get; set; } } public class LineItem { } public class Fee { } With RIA Services, if I want to retrieve an Order and include all of it's line items in the same network call, I can statically place an [Include] attribute on the above LineItems collection. This works great for a single scenario, but what happens when I need multiple "include strategies"? For instance, one situation might call for including the Fees collection and NOT the LineItems collection. Is there any way with RIA Services to control what's included at runtime without redefining your model and/or creating dtos with the attributes statically placed for each use-case?

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  • cflock do not throw timeout for same url called in same browser

    - by Pritesh Patel
    I am trying lock block on page test.cfm and below is code written on page. <cfscript> writeOutput("Before lock at #now()#"); lock name="threadlock" timeout="3" type="exclusive" { writeOutput("<br/>started at #now()#"); thread action="sleep" duration="10000"; writeOutput("<br/>ended at #now()#"); } writeOutput("<br/>After lock at #now()#"); </cfscript> assuming my url for page is http://localhost.local/test.cfm and running it on browser in two different tabs. I was expecting one of the url will throw timeout error after 3 second since another url lock it atleast for 10 seconds due to thread sleep. Surprisingly I do not get any timeout error rather second page call run after 10 seconds as first call finish execution. But I am appending some url parameter (e.g. http://localhost.local/test.cfm?q=1) will throw error. Also I am calling same url in different browser then one of the call will throw timeout issue. Is lock based on session and url? Update Here is output for two different cases: Case 1: TAB1 Url: http://localhost.local/test/test.cfm Before lock at {ts '2013-10-18 09:21:35'} started at {ts '2013-10-18 09:21:35'} ended at {ts '2013-10-18 09:21:45'} After lock at {ts '2013-10-18 09:21:45'} TAB2 Url: http://localhost.local/test/test.cfm Before lock at {ts '2013-10-18 09:21:45'} started at {ts '2013-10-18 09:21:45'} ended at {ts '2013-10-18 09:21:55'} After lock at {ts '2013-10-18 09:21:55'} Case 2: TAB1 Url: http://localhost.local/test/test.cfm Before lock at {ts '2013-10-18 09:27:18'} started at {ts '2013-10-18 09:27:18'} ended at {ts '2013-10-18 09:27:28'} After lock at {ts '2013-10-18 09:27:28'} TAB2 Url: http://localhost.local/test/test.cfm? (Added ? at the end) Before lock at {ts '2013-10-18 09:27:20'} A timeout occurred while attempting to lock threadlock. The error occurred in C:/inetpub/wwwroot/test/test.cfm: line 13 11 : 12 : <cfoutput>Before lock at #now()#</cfoutput> 13 : <cflock name="threadlock" timeout="3" type="exclusive"> 14 : <cfoutput><br/>started at #now()#</cfoutput> 15 : <cfthread action="sleep" duration="10000"/> ... Result for case 2 as expected. For case 1, strange thing I just noticed is tab 2 output "Before lock at {ts '2013-10-18 09:21:45'} indicates that whole request start after 10 seconds (means after the complete execution of first tab) when I have fired it in second URL just after 2 seconds of first tabs.

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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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