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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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• Where are the function literals in c++?

  - by academicRobot

  First of all, maybe literals is not the right term for this concept, but its the closest I could think of (not literals in the sense of functions as first class citizens). The idea is that when you make a conventional function call, it compiles to something like this: callq <immediate address> But if you make a function call using a function pointer, it compiles to something like this: mov <memory location>,%rax callq *%rax Which is all well and good. However, what if I'm writing a template library that requires a callback of some sort with a specified argument list and the user of the library is expected to know what function they want to call at compile time? Then I would like to write my template to accept a function literal as a template parameter. So, similar to template <int int_literal> struct my_template {...};` I'd like to write template <func_literal_t func_literal> struct my_template {...}; and have calls to func_literal within my_template compile to callq <immediate address>. Is there a facility in C++ for this, or a work around to achieve the same effect? If not, why not (e.g. some cataclysmic side effects)? How about C++0x or another language? Solutions that are not portable are fine. Solutions that include the use of member function pointers would be ideal. I'm not particularly interested in being told "You are a <socially unacceptable term for a person of low IQ>, just use function pointers/functors." This is a curiosity based question, and it seems that it might be useful in some (albeit limited) applications. It seems like this should be possible since function names are just placeholders for a (relative) memory address, so why not allow more liberal use (e.g. aliasing) of this placeholder. p.s. I use function pointers and functions objects all the the time and they are great. But this post got me thinking about the don't pay for what you don't use principle in relation to function calls, and it seems like forcing the use of function pointers or similar facility when the function is known at compile time is a violation of this principle, though a small one.

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• Perform Push Segue From a Tab View Controller

  - by user1416492

  I have a Tab Bar Controller App, the tab bar controller is forked into several "tab" view controller, in one of the view controller I want to redirect the user to an other view controller. I create a segue from that tab view controller to the destination view controller and given it an Identifer. And I call "performSegueWithIdentifier" in "viewDidAppear" to redirect the user. It works fine when the segue is "Modal", however since I want to retain the tabs, I want to call the segue through "Push". However, once I change the segue to "Push", it is not working anymore (it does not try to go to the destination view controller). The app did not crash on the simulator but just staying on the origin tab view controller.

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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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• Python: User-Defined Exception That Proves The Rule

  - by bandana

  Python documentations states: Exceptions should typically be derived from the Exception class, either directly or indirectly. the word 'typically' leaves me in an ambiguous state. consider the code: class good(Exception): pass class bad(object): pass Heaven = good() Hell = bad() >>> raise Heaven Traceback (most recent call last): File "<pyshell#163>", line 1, in <module> raise Heaven good >>> raise Hell Traceback (most recent call last): File "<pyshell#171>", line 1, in <module> raise Hell TypeError: exceptions must be classes or instances, not bad so when reading the python docs, should i change 'typically' with ''? what if i have a class hierarchy that has nothing to do with the Exception class, and i want to 'raise' objects belonging to the hierarchy? i can always raise an exception with an argument: raise Exception, Hell This seems slightly awkward to me What's so special about the Exception class, that only its family members can be raised?

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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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• 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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• 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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• How to override inner class methods if the inner class is defined as a property of the top class

  - by Maddy

  I have a code snippet like this class A(object): class b: def print_hello(self): print "Hello world" b = property(b) And I want to override the inner class b (please dont worry about the lowercase name) behaviour. Say, I want to add a new method or I want to change an existing method, like: class C(A): class b(A.b): def print_hello(self): print "Inner Class: Hello world" b = property(b) Now if I create C's object as c = C(), and call c.b I get TypeError: 'property' object is not callable error. How would I get pass this and call print_hello of the extended inner class? Disclaimer: I dont want to change the code for A class.

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• How should I generate HTML to represent class and its properties?

  - by Mike

  Currently I have a class that represents a document. This document needs to be displayed as HTML. I would like to have a method to call such as GetHTML() that would then call GetHTML() on any properties/sections of the document that needed to be rendered. I was initially thinking about using linq and XElement but am wondering if that may cause issues with certain tags in HTML. Would I better off using an HtmlTextWriter? I am open to any suggestions or best practives for this situation. Thanks!

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• How to manage db connections on server?

  - by simpatico

  I have a severe problem with my database connection in my web application. Since I use a single database connection for the whole application from singleton Database class, if i try concurrent db operations (two users) the database rollsback the transactions. This is my static method used: All threads/servlets call static Database.doSomething(...) methods, which in turn call the the below method. private static /* synchronized*/ Connection getConnection(final boolean autoCommit) throws SQLException { if (con == null) { con = new MyRegistrationBean().getConnection(); } con.setAutoCommit(true); //TODO return con; } What's the recommended way to manage this db connection/s I have, so that I don't incurr in the same problem.

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• GTKMM/C++ Window Event on loosing/regaining focus?

  - by ace

  How can i call a function whenever my gtkmm app looses or regains focus? Thanks.

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• php and javascript?

  - by anitabehal

  how to call php variables or queries in javascript?

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• How to build third party libraries with Android NDK

  - by heiko.witte

  How can I compile third party libraries with the android NDK? I am compiling a wrapper which implements the JNI functions as a shared lib, which depends on another 3rd party lib (HTK). I don't know how to setup the makefile. The following does not work: LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) include HTKLib/Android.mk LOCAL_PATH := $(call my-dir) include $(CLEAR_VARS) LOCAL_MODULE := gaitfuncs LOCAL_SRC_FILES := gaitfuncs.c %LOCAL_LDLIBS := -L$(SYSROOT)/usr/lib -llog include $(BUILD_SHARED_LIBRARY) The second makefile should then build a static lib which my shared lib links to. How can I include this subdir makefile properly? Is this the correct way of doing it? And as a bonus: Are there wildcards for the LOCAL_SRC_FILES variable to take all files ending in .c for example. 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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• 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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• How to store and access ajax data in javascript without using global variables ?

  - by mike_t2e

  I may be missing something obvious here, but how could I rewrite this code so that it doesn't need the theVariable to be a global variable ? <script language="javascript"> theVariable = ""; function setValue() /* called on page load */ { /* make ajax call to the server here */ theVariable = "a string of json data waiting to be eval()'d"; } function getValue() { alert(theVariable); } </script> <input type="button" onClick="javascript:getValue()" value="Get the value"> In my actual situation, the setValue function makes an ajax call to the server, receives a json string and the data from that is accessed when you mouseover various parts of the page. I end up using several global variables which works fine, but is messy and I'd like to know if there's a better and more elegant way of doing it ?

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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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• 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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• Public static variables and Android activity life cycle management

  - by jsstp24n5

  According to the documentation the Android OS can kill the activity at the rear of the backstack. So, say for example I have an app and open the Main Activity (let's call it Activity A). In this public activity class I declare and initialize a public static variable (let's call it "foo"). In Activity A's onCreate() method I then change the value of "foo." From Activity A the user starts another activity within my app called Activity B. Variable "foo" is used in Activity B. Activity B is then paused after the user navigates to some other activities in other apps. Eventually, after a memory shortage occurs, Activity A then Activity B can be killed. After the user navigates back to my app it restarts (actually "recreates") activity B. What happens: 1) Will variable "foo" at this point have the value that was set to it when Activity A's onCreate() method ran? 2) Variable "foo" does not exist? 3) Variable "foo" exists and but is now the initialized value and not the value set in Activity A's onCreate() method?

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• Remove items from SWT tables

  - by Dima

  This is more of an answer I'd like to share for the problem I was chasing for some time in RCP application using large SWT tables. The problem is the performance of SWT Table.remove(int start, int end) method. It gives really bad performance - about 50msec per 100 items on my Windows XP. But the real show stopper was on Vista and Windows 7, where deleting 100 items would take up to 5 seconds! Looking into the source code of the Table shows that there are huge amount of windowing events flying around in this call.. That brings the windowing system to its knees. The solution was to hide the damn thing during this call: table.setVisible(false); table.remove(from, to); table.setVisible(true); That does wonders - deleting 500 items on both XP & Windows7 takes ~15msec, which is just an overhead for printing out time stamps I used. nice :)

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• Calling a web service from a windows service

  - by Arun

  I'm sure there's an elegant solution to the problem but I just can't get my head around it. I am trying to call a web service from within a Windows service. The web service is secured (using Windows authentication). The account that the windows service runs under does have the rights to call the web service but I can't figure out how to get those credentials and send them off to the web service. The web service is WCF and is hosted on the same machine (in IIS) as the windows service.

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• user notification while waiting

  - by user315445

  I am writing a simple win forms app in C#. There is a method call in my method which loads files but is taking a while to respond. Below is the method call Directory.GetFiles(selectedFolder, "*.xml", SearchOption.AllDirectories); I want to notify this to users. Is there a way to show them that file loading is in progress? I want a simplest way. I suppose Splash screen is too costly for my app.

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• Performance of DirectX and Recent Windows Mobile Version

  - by Kevin

  I'm seeing very poor performance while using the managed DirectDraw wrappers for WindowsMobile. Microsoft.WindowsMobile.DirectX.Direct3D I would appear the biggest bottle neck is calling Device.Present() after building up the scene. When using the System.Diagnostics.Stopwatch and running this very trivial exmaple Using Sprites on MSDN I'm seeing it's taking approximately 150ms to call the Device.Present() method. I'm seeing this on my AT&T Tilt and on the emulator. In larger applications such as the UltimateGMan sample it's taking over a second to call this method. Does anyone have any experience with using DirectX on mobile devices? What am I missing? I would prefer to stay in the managed world but if I drop back into C++ would I see better performance?

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• pywinauto: taking more than one app windows

  - by Denis Barmenkov

  I have a GUI application which can create many similar windows on desktop. All windows have same title. I have to enumerate all dialogs with same title and make some tests against each of such dialogs. If I call: dialog = app['Window Name'] pywinauto returns a WindowSpecification object which is useful along with accessing controls by name. When I call: dialogs = app.windows_(title='Window Name') pywinauto returns me a list of HwndWrapper instances which are not so useful. How to obtain a list of windows with specified title but as WindowSpecification objects?

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