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• Including the functionality of a tool within another program?

  - by darren

  Hi there I would like to write an application, for my own interest, that graphically visualizes some network concepts. Basically I would like to show the output from tools like ping, traceroute and nmap. The most obvious approach seems to be to use pipes to call out to these tools from my C program, and process the information they return. However, I would like to avoid this heavy-handed approach if possible. My question is, is it possible to somehow link against these tools, or are there APIs that can be used to gain programatic access instead? If so, is this behavior available on a tool-by-tool basis only? One reason for wanting to do this is to keep everything in a single process / address space and to avoid dependance on these external tools. For example, if I wrote an iphone application, I would not be able to spawn processes to call out to the external tools themselves. Thanks for any advice or suggestions.

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• How to adjust microphone gain from C# (needs to work on XP & W7)...

  - by Ed

  First, note that I know there are a few questions like this already posted; however they don't seem to address the problem adequately. I have a C# application, with all the pInvoke hooks to talk to the waveXXX API, and I'm able to do capture and play back of audio with that. I'm also able to adjust speaker (WaveOut) volume with that API. The problem is that for whatever reason, that API does not allow me to adjust microphone (WaveIn) volume. So, I managed to find some mixer code that I've also pulled in and access through pInvoke and that allows me to adjust microphone volume, but only on my W7 PC. The mixer code I started with comes from here: http://social.msdn.microsoft.com/Forums/en-US/isvvba/thread/05dc2d35-1d45-4837-8e16-562ee919da85 and it works, but is written to adjust speaker volume. I added the SetMicVolume method shown here... public static void SetMicVolume(int mxid, int percentage) { bool rc; int mixer, vVolume; MIXERCONTROL volCtrl = new MIXERCONTROL(); int currentVol; mixerOpen(out mixer, mxid, 0, 0, MIXER_OBJECTF_WAVEIN); int type = MIXERCONTROL_CONTROLTYPE_VOLUME; rc = GetVolumeControl(mixer, MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE, type, out volCtrl, out currentVol); if (rc == false) { mixerClose(mixer); mixerOpen(out mixer, 0, 0, 0, 0); rc = GetVolumeControl(mixer, MIXERLINE_COMPONENTTYPE_SRC_MICROPHONE, type, out volCtrl, out currentVol); if (rc == false) throw new Exception("SetMicVolume/GetVolumeControl() failed"); } vVolume = ((int)((float)(volCtrl.lMaximum - volCtrl.lMinimum) / 100.0F) * percentage); rc = SetVolumeControl(mixer, volCtrl, vVolume); if (rc == false) throw new Exception("SetMicVolume/SetVolumeControl() failed"); mixerClose(mixer); } Note the "second attempt" to call GetVolumeControl(). This is done because on XP, in the first call to GetVolumeControl (refer to site above for that code), the call to mixerGetLineControlsA() fails with XP systems returning MIXERR_INVALCONTROL. Then, with this second attempt using mixerOpen(out mixer, 0, 0, 0, 0), the code doesn't return a failure but the mic gain is unaffected. Note, as I said above, this works on W7 (the second attempt is never executed because it doesn't fail using mixerOpen(out mixer, mxid, 0, 0, MIXER_OBJECTF_WAVEIN)). I admit to not having a good grasp on the mixer API, so that's what I'm looking into now; however if anyone has a clue why this would work on W7, but not XP, I'd sure like to hear it. Meanwhile, if I figure it out before I get a response, I'll post my own answer...

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• Singletons and other design issues

  - by Ahmed Saleh

  I have worked using different languages like C++/Java and currently AS3. Most applications were computer vision, and small 2D computer games. Most companies that I have worked for, they use Singletons in a language like AS3, to retrieve elements or classes in an easy way. Their problem is basically they needs some variables or to call other functions from other classes. In a language like AS3, there is no private constructor, and they write a hacky code to prevent new instances. In Java and C++ I also faced the situation that I need to use other classe's members or to call their functions in different classes. The question is, is there a better or another design, to let other classes interact with each others without using singletons? I feel that composition is the answer, but I need more detailed solutions or design suggestions.

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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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• c# Generic overloaded method dispatching ambiguous

  - by sebgod

  Hello, I just hit a situation where a method dispatch was ambiguous and wondered if anyone could explain on what basis the compiler (.NET 4.0.30319) chooses what overload to call interface IfaceA { } interface IfaceB<T> { void Add(IfaceA a); T Add(T t); } class ConcreteA : IfaceA { } class abstract BaseClassB<T> : IfaceB<T> { public virtual T Add(T t) { ... } public virtual void Add(IfaceA a) { ... } } class ConcreteB : BaseClassB<IfaceA> { // does not override one of the relevant methods } void code() { var concreteB = new ConcreteB(); // it will call void Add(IfaceA a) concreteB.Add(new ConcreteA()); } In any case, why does the compiler not warn me or even why does it compile? Thank you very much for any answers.

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• how to use @ in python.. and the @property and the @classmethods

  - by zjm1126

  this is my code: def a(): print 'sss' @a() def b(): print 'aaa' b() and the Traceback is: sss Traceback (most recent call last): File "D:\zjm_code\a.py", line 8, in <module> @a() TypeError: 'NoneType' object is not callable so how to use the '@' thanks updated class a: @property def b(x): print 'sss' aa=a() print aa.b it print : sss None how to use @property thanks updated2 and the classmethods: class a: @classmethods def b(x): print 'sss' aa=a() print aa.b the Traceback is : Traceback (most recent call last): File "D:\zjm_code\a.py", line 5, in <module> class a: File "D:\zjm_code\a.py", line 6, in a @classmethods NameError: name 'classmethods' is not defined

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• Best way to test if a generic type is a string? (c#)

  - by Rex M

  I have a generic class that should allow any type, primitive or otherwise. The only problem with this is using default(T). When you call default on a value type or a string, it initializes it to a reasonable value (such as empty string). When you call default(T) on an object, it returns null. For various reasons we need to ensure that if it is not a primitive type, then we will have a default instance of the type, not null. Here is attempt 1: T createDefault() { if(typeof(T).IsValueType) { return default(T); } else { return Activator.CreateInstance<T>(); } } Problem - string is not a value type, but it does not have a parameterless constructor. So, the current solution is: T createDefault() { if(typeof(T).IsValueType || typeof(T).FullName == "System.String") { return default(T); } else { return Activator.CreateInstance<T>(); } } But this feels like a kludge. Is there a nicer way to handle the string case?

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• WCF REST Does Not Contain All of the Relative File Path

  - by Brandon

  I have a RESTful WCF 3.5 endpoint as such: System.Security.User.svc This is supposed to represent the namespace of the User class and is desired behavior by our client. I have another endpoint I created for testing called: Echo.svc I am writing an overridden IHttpModule and in my module, I follow what almost everyone does by doing: string path = HttpContext.Current.Request.AppRelativeCurrentExecutionFilePath; If I make a call to: http://localhost/services/Echo/test My path variable has a value of '~/echo/test' However, when I make a call to: http://localhost/services/System.Security.User/test My path variable has a value of '~/system.security.user' In my 2nd situation, it is stripping off the '/test' on the end of any endpoint that contains multiple periods. This is undesired behavior and the only solution I have found to fixing this is some ugly string manipulation using the property which does contain the complete URL path: string rawPath = HttpContext.Current.Request.RawUrl; This returns '/services/system.security.user/test'. Does anyone know why my first situation does not return the rest of the URL path for endpoints that contain multiple periods in the name?

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• How can I quickly set up a RESTful site using PHP without a Framework?

  - by Sanoj

  I would like to quickly set up a RESTful site using PHP without learning a PHP Framework. I would like to use a single .htaccess-file in Apache (no mod_rewrite) or a single rule using Nginx, so I easyli can change web server without changing my code. So I want to direct all requests to a single PHP-file, and that file takes care of the RESTful-handling and call the right PHP-file. In example: The user request http://mysite.com/test The server sends all requests to rest.php The rest.php call test.php (maybe with a querystring). If this can be done, is there a free PHP-script that works like my rest.php? or how can I do this PHP-script?

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• multithreading with database

  - by Darsin

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

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• passing self data into a recursive function

  - by user272689

  I'm trying to set a function to do something like this def __binaryTreeInsert(self, toInsert, currentNode=getRoot(), parentNode=None): where current node starts as root, and then we change it to a different node in the method and recursivly call it again. However, i cannot get the 'currentNode=getRoot()' to work. If i try calling the funcion getRoot() (as above) it says im not giving it all the required variables, but if i try to call self.getRoot() it complains that self is an undefined variable. Is there a way i can do this without having to specify the root while calling this method?

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• [PHP] Sending Email Notification in Facebook JavaScript API

  - by Veera

  I'm trying to send a email notification to the user from my Facebook application. I'm trying to use the FaceBook JavaScript API function notifications_sendEmail(Array recipients, String subject, String text, String fbml, Object onRequestCompleted) I can understand the first four parameters. But what's the usage of the last parameter 'onRequestCompleted'. The Doc says it's the call back function. But, what if I do not want to execute a call back function? In this case, what will be a valid values to the parameter onRequestCompleted?

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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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• spidermonkey using JS_CallFunction for static function

  - by supersuraccoon

  JS_CallFunctionName can call a method of an object by name: JSObject* obj; JS_CallFunctionName(cx, obj, "doSomething", argc, vp, retVal); The code above works fine if the "doSomething" is a function declared in the prototype of the "obj". What I want to know is if there is a way to call a function that is a "class function". I tried: if(JS_HasProperty(getGlobalContext(), getGlobalObject(), "ClassToGet", &b)) { print("OK"); } and the output is "OK". But when tried: JS_GetProperty(getGlobalContext(), getGlobalObject(), "ClassToGet", &jsOwner); if (jsOwner != JSVAL_VOID) { } the jsOwner is a JSVAL_VOID. Maybe there is a function in SpiderMonkey can execute function in a JSClass ? Any suggestion will be appreciated, 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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• Starting new transaction in Spring bean

  - by Marcus

  We have: @Transactional(propagation = Propagation.REQUIRED) public class MyClass implementes MyInterface { ... MyInterface has a single method: go(). When go() executes we start a new transaction which commits/rollbacks when the method is complete - this is fine. Now let's say in go() we call a private method in MyClass that has @Transactional(propagation = Propagation.REQUIRES_NEW. It seems that Spring "ignores" the REQUIRES_NEW annotation and does not start a new transaction. I believe this is because Spring AOP operates on the interface level (MyInterface) and does not intercept any calls to MyClass methods. Is this correct? Is there any way to start a new transaction within the go() transaction? Is the only way to call another Spring managed bean that has transactions configured as REQUIRES_NEW? Update: Adding that when clients execute go() they do so via a reference to the interface, not the class: @Autowired MyInterface impl; impl.go();

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• DllImport Based on OS Platform

  - by Ngu Soon Hui

  I have a mixture of unmanaged code ( backend) and managed code ( front end), as such, I would need to call the unmanaged code from my managed code, using interop techniques and DllImport attribute. Now, I've compiled two versions of unmanaged code, for both 32 and 64 bit OS; they are named service32.dll and service64.dll respectively. So, in my .Net code, I would have to do a DllImport for both dlls: [DllImport(@"service32.dll")] //for 32 bit OS invocation public static void SimpleFunction(); [DllImport(@"service64.dll")] //for 64 bit OS invocation public static void SimpleFunction(); And call them depending on which platform my application is running on. The issue now is that for every unmanaged function, I have to declared it twice, one for 32 bit OS and one for 64 bit OS. This is a duplication of work, and everytime I change the signature of an unmanaged function, I have to modified it in two places. Is there anyway that I can change the argument in DllImport so that the correct dll will be invoked automagically, depending on the platform?

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• How do I access a php variable from JavaScript?

  - by anitabehal

  How do I call php variables or queries in JavaScript?

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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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• How to read log4j output to a web page?

  - by Ran

  I have a web page, used for admin purposes, which runs a task (image fetching from a remote site). In order to be able to debug the task using the browser only, no ssh etc, I'd like to be able to read all log output from the executing thread and spit it out to the web page. The task boils down to: Changing log level for current thread at the beginning of the call and restore when the call is done. Reading all log output by current thread and storing it in a string. So in pseudocode my execute() method would look like this: (I'm using struts2) public String execute() throws Exception { turnLoggingLevelToDebugOnlyForThisThread() ... do stuff... restoreLoggingLevelForThisThread() String logs = readAllLogsByThisThread(); } Can this be done with log4j? I'm using tomcat, struts2, log4j and slf4j.

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• def constrainedMatchPair(firstMatch,secondMatch,length):

  - by smart

  matches of a key string in a target string, where one of the elements of the key string is replaced by a different element. For example, if we want to match ATGC against ATGACATGCACAAGTATGCAT, we know there is an exact match starting at 5 and a second one starting at 15. However, there is another match starting at 0, in which the element A is substituted for C in the key, that is we match ATGC against the target. Similarly, the key ATTA matches this target starting at 0, if we allow a substitution of G for the second T in the key string. consider the following steps. First, break the key string into two parts (where one of the parts could be an empty string). Let's call them key1 and key2. For each part, use your function from Problem 2 to find the starting points of possible matches, that is, invoke starts1 = subStringMatchExact(target,key1) and starts2 = subStringMatchExact(target,key2) The result of these two invocations should be two tuples, each indicating the starting points of matches of the two parts (key1 and key2) of the key string in the target. For example, if we consider the key ATGC, we could consider matching A and GC against a target, like ATGACATGCA (in which case we would get as locations of matches for A the tuple (0, 3, 5, 9) and as locations of matches for GC the tuple (7,). Of course, we would want to search over all possible choices of substrings with a missing element: the empty string and TGC; A and GC; AT and C; and ATG and the empty string. Note that we can use your solution for Problem 2 to find these values. Once we have the locations of starting points for matches of the two substrings, we need to decide which combinations of a match from the first substring and a match of the second substring are correct. There is an easy test for this. Suppose that the index for the starting point of the match of the first substring is n (which would be an element of starts1), and that the length of the first substring is m. Then if k is an element of starts2, denoting the index of the starting point of a match of the second substring, there is a valid match with one substitution starting at n, if n+m+1 = k, since this means that the second substring match starts one element beyond the end of the first substring. finally the question is Write a function, called constrainedMatchPair which takes three arguments: a tuple representing starting points for the first substring, a tuple representing starting points for the second substring, and the length of the first substring. The function should return a tuple of all members (call it n) of the first tuple for which there is an element in the second tuple (call it k) such that n+m+1 = k, where m is the length of the first substring.

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• C# - Silverlight - Dynamically calling a method

  - by cmaduro

  Is there anyway in C# to call a method based on a Enum and/or class? Say if I were to call Controller<Actions.OnEdit, Customer>(customer); Could I do something like this then? public void Controller<TAction, TParam>(TParam object) { Action<TParam> action = FindLocalMethodName(TAction); action(object); } private Action<T> FindLocalMethodName(Enum method) { //Use reflection to find a metode with //the name corresponding to method.ToString() //which accepts a parameters type T. }

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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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• 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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• Approaches to timing out sessions on a web app using AJAX autorefreshes

  - by Braintapper

  I'm writing a web application that autorefreshes data with an AJAX call at set intervals. Because it's doing that, server side user sessions never time out, since the last activity is refreshed with every ajax call. Are there good client side rules I could implement to time out the user? I.e. should I track mouse movements in the browser, etc., or should I point the AJAX calls to URLs that don't refresh the session? I like that my AJAX calls hit a session-enabled URL, because I can also validate that the user is logged in, etc. Any thoughts in terms of whether I should even bother timing out the users?

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