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  • debugging scaffolding contingent upon degbugging boolean (java)

    - by David
    Recently i've found myself writing a lot of methods with what i can only think to call debugging scaffolding. Here's an example: public static void printArray (String[] array, boolean bug) { for (int i = 0; i<array.lenght; i++) { if (bug) System.out.print (i) ; //this line is what i'm calling the debugging scaffolding i guess. System.out.println(array[i]) ; } } in this method if i set bug to true, wherever its being called from maybe by some kind of user imput, then i get the special debugging text to let me know what index the string being printed as at just in case i needed to know for the sake of my debugging (pretend a state of affairs exists where its helpful). All of my questions more or less boil down to the question: is this a good idea? but with a tad bit more objectivity: Is this an effective way to test my methods and debug them? i mean effective in terms of efficiency and not messing up my code. Is it acceptable to leave the if (bug) stuff ; code in place after i've got my method up and working? (if a definition of "acceptability" is needed to make this question objective then use "is not a matter of programing controversy such as ommiting brackets in an if(boolean) with only one line after it, though if you've got something better go ahead and use your definition i won't mind) Is there a more effective way to accomplish the gole of making debugging easier than what i'm doing? Anything you know i mean to ask but that i have forgotten too (as much information as makes sense is appreciated).

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  • Pointer Implementation Details in C

    - by Will Bickford
    I would like to know architectures which violate the assumptions I've listed below. Also I would like to know if any of the assumptions are false for all architectures (i.e. if any of them are just completely wrong). sizeof(int *) == sizeof(char *) == sizeof(void *) == sizeof(func_ptr *) The in-memory representation of all pointers for a given architecture is the same regardless of the data type pointed to. The in-memory representation of a pointer is the same as an integer of the same bit length as the architecture. Multiplication and division of pointer data types are only forbidden by the compiler. NOTE: Yes I know this is nonsensical. What I mean is - is there hardware support to forbid this incorrect usage? All pointer values can be casted to a single integer. In other words, what architectures still make use of segments and offsets? Incrementing a pointer is equivalent to adding sizeof(the pointed data type) to the memory address stored by the pointer. If p is an int32* then p+1 is equal to the memory address 4 bytes after p. I'm most used to pointers being used in a contiguous, virtual memory space. For that usage, I can generally get by thinking of them as addresses on a number line. See (http://stackoverflow.com/questions/1350471/pointer-comparison/1350488#1350488).

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  • Is Google the only OpenID provider that requires "identifier_select"?

    - by Skrat
    I am developing an OpenID consumer in PHP and am using the fantastic LightOpenID library (http://gitorious.org/lightopenid). Basing my code off of that found in the example client script I have successfully created a consumer. However, I've run across a snag: Google requires the openid.identity and openid.claimed_id to be set to "http://specs.openid.net/auth/2.0/identifier_select" (see here). If I do that it works but other providers (i.e. AOL) don't. Here are my questions: Is Google a corner case –– is it the only OpenID provider where identifier_select is required, contrary to the OpenID specs? Is there a shortcoming in the LightOpenID library? Is my understanding of how OpenID works incorrect? If Google is not the only provider that requires identifier_select are there a finite number of them which I'll just hardcode in, or is there someway to determine this through the OpenID spec? I'm new to the internals of OpenID so I wouldn't be surprised if this is a dumb question. I haven't been able to find any info on this subject after scouring the Internet.

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  • How to handle large dataset with JPA (or at least with Hibernate)?

    - by Roman
    I need to make my web-app work with really huge datasets. At the moment I get either OutOfMemoryException or output which is being generated 1-2 minutes. Let's put it simple and suppose that we have 2 tables in DB: Worker and WorkLog with about 1000 rows in the first one and 10 000 000 rows in the second one. Latter table has several fields including 'workerId' and 'hoursWorked' fields among others. What we need is: count total hours worked by each user; list of work periods for each user. The most straightforward approach (IMO) for each task in plain SQL is: 1) select Worker.name, sum(hoursWorked) from Worker, WorkLog where Worker.id = WorkLog.workerId group by Worker.name; //results of this query should be transformed to Multimap<Worker, Long> 2) select Worker.name, WorkLog.start, WorkLog.hoursWorked from Worker, WorkLog where Worker.id = WorkLog.workerId; //results of this query should be transformed to Multimap<Worker, Period> //if it was JDBC then it would be vitally //to set resultSet.setFetchSize (someSmallNumber), ~100 So, I have two questions: how to implement each of my approaches with JPA (or at least with Hibernate); how would you handle this problem (with JPA or Hibernate of course)?

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  • Generating PDF document using XSLT

    - by Nair
    I have one huge XML document. I have set of XSL representing each node in the XML. These XSL also have java script to generate the dynamic content. It uses images which are in seperate images folder and it uses fonts as well. At present, I have a program which displays all the nodes that can be transformed and user click on one of the node and the program performs XSLT and display the content in HTML format on IE screen. I want to write a program (.Net , C# or any .Net language) which will allow user to do XSLT tranform on all the available notes and create one PDF document. My initial requirement was to display all the document in the IE itself, so I reused the existing code, and foreach node, perform XSLT and then append it to the current HTML with a page break and it worked ok till we hit huge files. So the requirement changed to create one PDF file with all the nodes. I have couple of questions, 1. What is the best way to create PDF file using XSLT transformation? 2. Since the images are relative path, if we generate the XSLT in html and then write it to a output stream will it loose the images? 3. Will the font be preserved in the PDF document? Really appriciate if someone could point me to some good example that I can take and run with it. Thanks a lot.

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  • Return enum instead of bool from function for clarity ?

    - by Moe Sisko
    This is similar to : http://stackoverflow.com/questions/2908876/net-bool-vs-enum-as-a-method-parameter but concerns returning a bool from a function in some situations. e.g. Function which returns bool : public bool Poll() { bool isFinished = false; // do something, then determine if finished or not. return isFinished; } Used like this : while (!Poll()) { // do stuff during wait. } Its not obvious from the calling context what the bool returned from Poll() means. It might be clearer in some ways if the "Poll" function was renamed "IsFinished()", but the method does a bit of work, and (IMO) would not really reflect what the function actually does. Names like "IsFinished" also seem more appropriate for properties. Another option might be to rename it to something like : "PollAndReturnIsFinished" but this doesn't feel right either. So an option might be to return an enum. e.g : public enum Status { Running, Finished } public Status Poll() { Status status = Status.Running; // do something, then determine if finished or not. return status; } Called like this : while (Poll() == Status.Running) { // do stuff during wait. } But this feels like overkill. Any ideas ?

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  • Licensing iPhone apps per user in existing system

    - by Alxandr
    I've been asked by my job to write a iPhone app for an existing system for managing worktasks. This system is proprietary and costs money, so in order to login you need to be a customer. Now, I've got two questions about the legality of licensing iPhone apps with this system: My company would like to be able to sell the app for profit, but not as a one-time payment, but as a added subscription-fee to the already existing one. Is it legal for us (according with the terms of distributing an iPhone app on the Apple App Store) to do this? That way we'll just add another field to the users-database saying weather or not iPhone is enabled for them, and distribute the app as a free app on App Store. If the previous question is not legal, we'd like to just create a free app and distribute it as part of the existing system. In other words, no extra fee for using the iPhone app for the users, but still free distribution trough App Store. Due to our company not being american or having an office in the U.S. at all enterprice account is not an option. Please let me know if there is anything wrong with any of the above approaches.

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  • C# reflection instantiation

    - by NickLarsen
    I am currently trying to create a generic instance factory for which takes an interface as the generic parameter (enforced in the constructor) and then lets you get instantiated objects which implement that interface from all types in all loaded assemblies. The current implementation is as follows:     public class InstantiationFactory     {         protected Type Type { get; set; }         public InstantiationFactory()         {             this.Type = typeof(T);             if (!this.Type.IsInterface)             {                 // is there a more descriptive exception to throw?                 throw new ArgumentException(/* Crafty message */);             }         }         public IEnumerable GetLoadedTypes()         {             // this line of code found in other stack overflow questions             var types = AppDomain.CurrentDomain.GetAssemblies()                 .SelectMany(a = a.GetTypes())                 .Where(/* lambda to identify instantiable types which implement this interface */);             return types;         }         public IEnumerable GetImplementations(IEnumerable types)         {             var implementations = types.Where(/* lambda to identify instantiable types which implement this interface */                 .Select(x = CreateInstance(x));             return implementations;         }         public IEnumerable GetLoadedImplementations()         {             var loadedTypes = GetLoadedTypes();             var implementations = GetImplementations(loadedTypes);             return implementations;         }         private T CreateInstance(Type type)         {             T instance = default(T);             var constructor = type.GetConstructor(Type.EmptyTypes);             if (/* valid to instantiate test */)             {                 object constructed = constructor.Invoke(null);                 instance = (T)constructed;             }             return instance;         }     } It seems useful to me to have my CreateInstance(Type) function implemented as an extension method so I can reuse it later and simplify the code of my factory, but I can't figure out how to return a strongly typed value from that extension method. I realize I could just return an object:     public static class TypeExtensions     {         public object CreateInstance(this Type type)         {             var constructor = type.GetConstructor(Type.EmptyTypes);             return /* valid to instantiate test */ ? constructor.Invoke(null) : null;         }     } Is it possible to have an extension method create a signature per instance of the type it extends? My perfect code would be this, which avoids having to cast the result of the call to CreateInstance():     Type type = typeof(MyParameterlessConstructorImplementingType);     MyParameterlessConstructorImplementingType usable = type.CreateInstance();

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  • greasemonkey: perform GM_xmlhttpRequest() from eval (follow up)

    - by Paul Tarjan
    How can you call GM_xmlhttpRequest inside of an eval where you are evaling some complicated code, some of which calls GM_xmlhttpRequest. This is a follow up to http://stackoverflow.com/questions/1074236 Here is some sample code: // ==UserScript== // @name Test GM AJAX // ==/UserScript== console = unsafeWindow.console; function fetch(msg) { console.log('fetching: '+msg); GM_xmlhttpRequest({ method: 'GET', url: 'http://google.com', onload: function(responseDetails) { console.log(msg); } }); } function complicated(arg1, arg2) { fetch(arg1 + arg2); } console.log('trying'); var code = 'complicated("Ya", "y!")'; function myEval(code) { eval(code); eval('setTimeout(function(){'+code+'},0)'); eval('setTimeout(fetch,0)'); eval('setTimeout(function(){console.log("here");fetch("cool")},0)'); fetch("BOO"); } myEval(code); which outputs: trying fetching: Yay! fetching: BOO fetching: Yay! fetching: 30 here fetching: cool BOO 30 So the only fetch that worked was the setTimeout(fetch,0) but I need to actually execute the code which includes come complicated code. Any ideas?

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  • Why doesn't this jQuery snippet work in IE8 like it does in Firefox or Chrome (Live Demo Included) ?

    - by Siracuse
    I asked for help earlier on Stackoverflow involving highlighting spans with the same Class when a mouse hovers over any Span with that same Class. It is working great: http://stackoverflow.com/questions/2709686/how-can-i-add-a-border-to-all-the-elements-that-share-a-class-when-the-mouse-has $('span[class]').hover( function() { $('.' + $(this).attr('class')).css('background-color','green'); }, function() { $('.' + $(this).attr('class')).css('background-color','yellow'); } ) Here is an example of it in usage: http://dl.dropbox.com/u/638285/0utput.html However, it doesn't appear to work properly in IE8, while it DOES work in Chrome/Firefox. Here is a screenshot of it in IE8, with my mouse hovered over the " min) { min" section in the middle. As you can see, it highlighted the span that the mouse is hovering over perfectly fine. However, it has also highlighted some random spans above and below it that don't have the same class! Only the span's with the same Class as the one where the mouse is over should be highlighted green. In this screenshot, only that middle green section should be green. Here is a screenshot of it working properly in Firefox/Chrome with my mouse in the exact same position: This screenshot is correct as the span that the mouse is over (the green section) is the only one in this section that shares that class. Why is IE8 randomly green-highlighting spans when it shouldn't be (they don't share the same class) using my little jQuery snippet? Again, if you want to see it live I have it here: http://dl.dropbox.com/u/638285/0utput.html

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  • Webbrowser locks first Excel Instance

    - by figus
    VB.NET 2008 - WinForms Hi Everyone! I've been looking for an answer to my problem but I only find more questions related to my problem... The thing is that I'm using a AxWebBrowser control in VB.NET 2008 to open a excel file in a WindowsForm, it opens succesfully and everything... but the problem is this: If I had a Excel File Open before opening another Excel File in my WebBrowser Control, the window that contains the file that was already open gets locked... (I can't give focus to that Excel window... If I click on it, the focus returns to my application) I tried creating a new excel instance with CreateObject("Excel.Application") just before loading the file, but the WebBrowser locks the first Excel Instance... Is there a way to lock it to the last instance??? I use the WebBrowser1.Navigate(Url) method to load the file... where Url is a String like C:\myExcelFile.xlsm WebBrowser1.Document.Application.UserControl is also True, but it get's locked. Any Suggestion?? Thanks in Advance!!!

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  • Accomplishing This Style of Drop-Down Menus in jQuery

    - by Maxim Z.
    I was browsing the web and found this site. I noticed how the nav bar drop-down works, and I want to implement something similar on my website. Afer going into the source code of the page, I found that those drop-down areas are contained in divs with class fOut. It turns out that this is being done with MooTools. Here is the script itself (referenced in the original page after the Mootools script itself): window.addEvent('domready', function() { $("primaryNav").getChildren("li").addEvents({ "mouseenter": function(){ $(this).addClass("hover").getChildren("a").addClass("hover"); }, "mouseleave": function(){ $(this).removeClass("hover").getChildren("a").removeClass("hover"); } }); $$(".fOut").each(function(el,i){ var ifr = $(document.createElement("iframe")); ifr.className = "ieBgIframe"; ifr.frameBorder = "0"; ifr.src="about:blank"; ifr.injectInside(el); var p = el.getParent(); p.addClass("hover"); var h = el.getSize().size.y; p.removeClass("hover"); ifr.height=h; }); $$(".olderVersionsToggle").addEvents({ "click": function(e){ var event = new Event(e); event.stop(); var p = $(this).getParent().getNext(); if(p.hasClass("open")){ p.removeClass("open"); $(this).setText("Show previous versions..."); } else{ p.addClass("open"); $(this).setText("Hide previous versions..."); } return false; } }); }); My Question(s) I have two questions about this code. How does it work? I don't quite understand what it's doing, with the iframes and all. How can this be implemented in jQuery?

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  • What is the best URL strategy to handle multiple search parameters and operators?

    - by Jon Winstanley
    Searching with mutltiple Parameters In my app I would like to allow the user to do complex searches based on several parameters, using a simple syntax similar to the GMail functionality when a user can search for "in:inbox is:unread" etc. However, GMail does a POST with this information and I would like the form to be a GET so that the information is in the URL of the search results page. Therefore I need the parameters to be formatted in the URL. Requirements: Keep the URL as clean as possible Avoid the use of invalid URL chars such as square brackets Allow lots of search functionality Have the ability to add more functions later. I know StackOverflow allows the user to search by multiple tags in this way: http://stackoverflow.com/questions/tagged/c+sql However, I'd like to also allow users to search with multiple additional parameters. Initial Design My design is currently to do use URLs such as these: http://example.com/search/tagged/c+sql/searchterm/transactions http://example.com/search/searchterm/transactions http://example.com/search/tagged/c+sql http://example.com/search/tagged/c+sql/not-tagged/java http://example.com/search/tagged/c+sql/created/yesterday http://example.com/search/created_by/user1234 I intend to parse the URL after the search parameter, then decide how to construct my search query. Has anyone seen URL parameters like this implemented well on a website? If so, which do it best?

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  • Approach for fixing NoClassDefFoundError?

    - by DJC
    I'm seeing this question is getting asked a lot in many different contexts. Perhaps we can set some strategies for locating and fixing it? I'm noobish myself so all I can contribute are horror stories and questions, sorry... It seems this is thrown when a class is visible at compile time but not at run time... how can this happen? In my case I am developing an app that uses the Google APIs, in Eclipse, for the Android platform. I've configured the Project Properties / Java Build Path / Libraries to include the gdata .jars and all is well. When I execute in the emulator I get a force close and the logcat shows a NoClassDefFoundError on a simple new ContactsService("myApp"); I've also tried a new CalendarService("myApp") with the same results. Is it possible or desirable to statically bind at compile time to avoid the problem? How could dynamic binding of an add-on library work in the mobile environment anyway? Either it has to be bound into my .apk or else I need to "install" it? ... hmmm. Advice much appreciated.

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  • MSBuild script fails but produces no errors

    - by Kate
    I have a MSBuild script that I am executing through TeamCity. One of the tasks that is runs is from Xheo DeploxLX CodeVeil which obfuscates some DLLs. The task I am using is called VeilProject. I have run the CodeVeil Project through the interface manually and it works correctly, so I think I can safely assume that the actual obfuscate process is ok. This task used to take around 40 minutes and the rest of the MSBuild file executed perfectly and finished without errors. For some reason this task is now taking 1hr 20 minutes or so to execute. Once the VeilProject task is finished the output from the task says it completely successfully, however the MSBuild script fails at this point. I have a task directly after the VeilProject task and it does not get outputted. Using diagnostic output from MSBUild I can see the following: My questions are: Would it be possible that the MSBuild script has timed out? Once the task has completed it is after a certain timeout period so it just fails? Why would the build fail with no errors and no warnings? [05:39:06]: [Target "Obfuscate"] Finished. [05:39:06]: [Target "Obfuscate"] Saving exception map [05:49:21]: [Target "Obfuscate"] Ended at 11/05/2010 05:49:21, ~1 hour, 48 minutes, 6 seconds [05:49:22]: [Target "Obfuscate"] Done. [05:49:51]: MSBuild output: Ended at 11/05/2010 05:49:21, ~1 hour, 48 minutes, 6 seconds (TaskId:8) Done. (TaskId:8) Done executing task "VeilProject" -- FAILED. (TaskId:8) Done building target "Obfuscate" in project "AMK_Release.proj.teamcity.patch.tcprojx" -- FAILED.: (TargetId:12) Done Building Project "C:\Builds\Scripts\AMK_Release.proj.teamcity.patch.tcprojx" (All target(s)) -- FAILED. Project Performance Summary: 6535484 ms C:\Builds\Scripts\AMK_Release.proj.teamcity.patch.tcprojx 1 calls 6535484 ms All 1 calls Target Performance Summary: 156 ms PreClean 1 calls 266 ms SetBuildVersionNumber 1 calls 2406 ms CopyFiles 1 calls 6532391 ms Obfuscate 1 calls Task Performance Summary: 16 ms MakeDir 2 calls 31 ms TeamCitySetBuildNumber 1 calls 31 ms Message 1 calls 62 ms RemoveDir 2 calls 234 ms GetAssemblyIdentity 1 calls 2406 ms Copy 1 calls 6528047 ms VeilProject 1 calls Build FAILED. 0 Warning(s) 0 Error(s) Time Elapsed 01:48:57.46 [05:49:52]: Process exit code: 1 [05:49:55]: Build finished

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  • Problem with Railscast #197 - Nested Model Form Part 2

    - by sscirrus
    I'm trying to implement Ryan's Railscast #197 in a system with Questions, Answers, and (multiple choice) Options. http://railscasts.com/episodes/197-nested-model-form-part-2. I have successfully implemented the nesting among these forms/partials. The simpler 'check box' way to delete records works properly. The problem occurs when I try to add/delete records. I have copied the code exactly as it appears in his Railscast: #new.html.erb <%= javascript_include_tag :defaults, :cache => true %> <% f.fields_for :in_options do |builder| %> <%= render "option_fields", :f => builder %> <% end %> #_option_fields.html.erb partial <%= f.hidden_field :_destroy %> <%= link_to_function "remove", "remove_fields(this)" %> #application_helper.rb (exact same as #197) def link_to_remove_fields(name, f) f.hidden_field(:_destroy) + link_to_function(name, "remove_fields(this)") end def link_to_add_fields(name, f, association) new_object = f.object.class.reflect_on_association(association).klass.new fields = f.fields_for(association, new_object, :child_index => "new_#{association}") do |builder| render(association.to_s.singularize + "_fields", :f => builder) end link_to_function(name, h("add_fields(this, \"#{association}\", \"#{escape_javascript(fields)}\")")) end #application.js (exact same as #197. I have an Event.addbehavior below this code.) function remove_fields(link) { $(link).previous("input[type=hidden]").value = "1"; $(link).up(".fields").hide(); } function add_fields(link, association, content) { var new_id = new Date().getTime(); var regexp = new RegExp("new_" + association, "g") $(link).up().insert({ before: content.replace(regexp, new_id) }); } 2 problems: When I click on the 'remove' link it doesn't remove - it just shifts the page up or down. When I include link_to_add_fields "Add Answer", f, :answers, I get undefined method `klass' for nil:NilClass. Thanks everyone.

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  • Valgrind 'noise', what does it mean?

    - by Chris Huang-Leaver
    When I used valgrind to help debug an app I was working on I notice a huge about of noise which seems to be complaining about standard libraries. As a test I did this; echo 'int main() {return 0;}' | gcc -x c -o test - Then I did this; valgrind ./test ==1096== Use of uninitialised value of size 8 ==1096== at 0x400A202: _dl_new_object (in /lib64/ld-2.10.1.so) ==1096== by 0x400607F: _dl_map_object_from_fd (in /lib64/ld-2.10.1.so) ==1096== by 0x4007A2C: _dl_map_object (in /lib64/ld-2.10.1.so) ==1096== by 0x400199A: map_doit (in /lib64/ld-2.10.1.so) ==1096== by 0x400D495: _dl_catch_error (in /lib64/ld-2.10.1.so) ==1096== by 0x400189E: do_preload (in /lib64/ld-2.10.1.so) ==1096== by 0x4003CCD: dl_main (in /lib64/ld-2.10.1.so) ==1096== by 0x401404B: _dl_sysdep_start (in /lib64/ld-2.10.1.so) ==1096== by 0x4001471: _dl_start (in /lib64/ld-2.10.1.so) ==1096== by 0x4000BA7: (within /lib64/ld-2.10.1.so) * large block of similar snipped * ==1096== Use of uninitialised value of size 8 ==1096== at 0x4F35FDD: (within /lib64/libc-2.10.1.so) ==1096== by 0x4F35B11: (within /lib64/libc-2.10.1.so) ==1096== by 0x4A1E61C: _vgnU_freeres (vg_preloaded.c:60) ==1096== by 0x4E5F2E4: __run_exit_handlers (in /lib64/libc-2.10.1.so) ==1096== by 0x4E5F354: exit (in /lib64/libc-2.10.1.so) ==1096== by 0x4E48A2C: (below main) (in /lib64/libc-2.10.1.so) ==1096== ==1096== ERROR SUMMARY: 3819 errors from 298 contexts (suppressed: 876 from 4) ==1096== malloc/free: in use at exit: 0 bytes in 0 blocks. ==1096== malloc/free: 0 allocs, 0 frees, 0 bytes allocated. ==1096== For counts of detected errors, rerun with: -v ==1096== Use --track-origins=yes to see where uninitialised values come from ==1096== All heap blocks were freed -- no leaks are possible. You can see the full result here: http://pastebin.com/gcTN8xGp I have two questions; firstly is there a way to suppress all the noise? --show-below-main is set to no by default, but there doesn't appear to be a --show-after-main equivalent.

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  • Can I use POSIX signals in my Perl program to create event-driven programming?

    - by Shiftbit
    Is there any POSIX signals that I could utilize in my Perl program to create event-driven programming? Currently, I have multi-process program that is able to cross communicate but my parent thread is only able to listen to listen at one child at a time. foreach (@proc) { sysread(${$_}{'read'}, my $line, 100); #problem here chomp($line); print "Parent hears: $line\n"; } The problem is that the parent sits in a continual wait state until it receives it a signal from the first child before it can continue on. I am relying on 'pipe' for my intercommunication. My current solution is very similar to: http://stackoverflow.com/questions/2558098/how-can-i-use-pipe-to-facilitate-interprocess-communication-in-perl If possible I would like to rely on a $SIG{...} event or any non-CPAN solution. Update: As Jonathan Leffler mentioned, kill can be used to send a signal: kill USR1 = $$; # send myself a SIGUSR1 My solution will be to send a USR1 signal to my child process. This event tells the parent to listen to the particular child. child: kill USR1 => $parentPID if($customEvent); syswrite($parentPipe, $msg, $buffer); #select $parentPipe; print $parentPipe $msg; parent: $SIG{USR1} = { #get child pid? sysread($array[$pid]{'childPipe'}, $msg, $buffer); }; But how do I get my the source/child pid that signaled the parent? Have the child Identify itself in its message. What happens if two children signal USR1 at the same time?

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  • What are some good ways to store performance statistics in a database for querying later?

    - by Nathan
    Goal: Store arbitrary performance statistics of stuff that you care about (how many customers are currently logged on, how many widgets are being processed, etc.) in a database so that you can understand what how your servers are doing over time. Assumptions: A database is already available, and you already know how to gather the information you want and are capable of putting it in the database however you like. Some Ideal Attributes of a Solution Causes no noticeable performance hit on the server being monitored Has a very high precision of measurement Does not store useless or redundant information Is easy to query (lends itself to gathering/displaying useful information) Lends itself to being graphed easily Is accurate Is elegant Primary Questions 1) What is a good design/method/scheme for triggering the storing of statistics? 2) What is a good database design for how to actually store the data? Example answers...that are sort of vague and lame... 1) I could, once per [fixed time interval], store a row of data with all the performance measurements I care about in each column of one big flat table indexed by timestamp and/or server. 2) I could have a daemon monitoring performance stuff I care about, and add a row whenever something changes (instead of at fixed time intervals) to a flat table as in #1. 3) I could trigger either as in #2, but I could store information about each aspect of performance that I'm measuring in separate tables, opening up the possibility of adding tons of rows for often-changing items, and few rows for seldom-changing items. Etc. In the end, I will implement something, even if it's some super-braindead approach I make up myself, but I'm betting there are some really smart people out there willing to share their experiences and bright ideas!

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  • wxpython: adding panel to wx.Frame disables/conflicts with wx.Frame's OnPaint?!

    - by sdaau
    Hi all, I just encountered this strange situation: I found an example, where wx.Frame's OnPaint is overridden, and a circle is drawn. Funnily, as soon as I add even a single panel to the frame, the circle is not drawn anymore - in fact, OnPaint is not called at all anymore ! Can anyone explain me if this is the expected behavior, and how to correctly handle a wx.Frame's OnPaint, if the wx.Frame has child panels ? Small code example is below.. Thanks in advance for any answers, Cheers! The code: #!/usr/bin/env python # http://www.linuxquestions.org/questions/programming-9/wxwidgets-wxpython-drawing-problems-with-onpaint-event-703946/ import wx class MainWindow(wx.Frame): def __init__(self, parent, title, size=wx.DefaultSize): wx.Frame.__init__(self, parent, wx.ID_ANY, title, wx.DefaultPosition, size) self.circles = list() self.displaceX = 30 self.displaceY = 30 circlePos = (self.displaceX, self.displaceY) self.circles.append(circlePos) ## uncommenting either only first, or both of ## the commands below, causes OnPaint *not* to be called anymore! #~ self.panel = wx.Panel(self, wx.ID_ANY) #~ self.mpanelA = wx.Panel(self.panel, -1, size=(200,50)) self.Bind(wx.EVT_PAINT, self.OnPaint) def OnPaint(self, e): print "OnPaint called" dc = wx.PaintDC(self) dc.SetPen(wx.Pen(wx.BLUE)) dc.SetBrush(wx.Brush(wx.BLUE)) # Go through the list of circles to draw all of them for circle in self.circles: dc.DrawCircle(circle[0], circle[1], 10) def main(): app = wx.App() win = MainWindow(None, "Draw delayed circles", size=(620,460)) win.Show() app.MainLoop() if __name__ == "__main__": main()

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  • Access violations in strange places when using Windows file dialogs

    - by Robert Oschler
    A long time ago I found out that I was getting access violations in my code due to the use of the Delphi Open File and/or Save File dialogs, which encapsulate the Windows dialogs. I asked some questions on a few forums and I was told that it may have been due to the way some programs add hooks to the shell system that result in DLLs getting injected in every process, some of which can cause havoc with a program. For the record, the programming environment I use is Delphi 6 Professional running on Windows XP 32-bit. At the time I got around it by not using Delphi's Dialog components and instead calling straight into comdlg32.dll. This solved the problem wonderfully. Today I was working with memory mapped files for the first time and sure enough, access violations started cropping up in weird parts of the code. I tried my comdlg32.dll direct calls and this time it didn't help. To isolate the problem as a test I created a list box with the exact same files I was using during testing. These are the exact same test files I was selecting from an Open File dialog and then launching my memory mapped file with. I set things up so that by clicking on a file in the list box, I would use that file in my memory mapped file test instead of calling into a comdlg32.dll dialog function to select a test file. Again, the access violatons vanished. To show you how dramatic a fix it was I went from experiencing an access violation within 1 to 3 trials to none at all. Unfortunately, it's going to bite me later on of course when I do need to use file dialogs. Has anyone else dealt with this issue too and found the real culprit? Did any of you find a solution I could use to fix this problem instead of dancing around it like I am now? Thanks in advance.

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  • function objects versus function pointers

    - by kumar_m_kiran
    Hi All, I have two questions related to function objects and function pointers, Question : 1 When I read the different uses sort algorithm of STL, I see that the third parameter can be a function objects, below is an example class State { public: //... int population() const; float aveTempF() const; //... }; struct PopLess : public std::binary_function<State,State,bool> { bool operator ()( const State &a, const State &b ) const { return popLess( a, b ); } }; sort( union, union+50, PopLess() ); Question : Now, How does the statement, sort(union, union+50,PopLess()) work? PopLess() must be resolved into something like PopLess tempObject.operator() which would be same as executing the operator () function on a temporary object. I see this as, passing the return value of overloaded operation i.e bool (as in my example) to sort algorithm. So then, How does sort function resolve the third parameter in this case? Question : 2 Question Do we derive any particular advantage of using function objects versus function pointer? If we use below function pointer will it derive any disavantage? inline bool popLess( const State &a, const State &b ) { return a.population() < b.population(); } std::sort( union, union+50, popLess ); // sort by population PS : Both the above references(including example) are from book "C++ Common Knowledge: Essential Intermediate Programming" by "Stephen C. Dewhurst". I was unable to decode the topic content, thus have posted for help. Thanks in advance for your help.

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  • Binary files printing and desired precision

    - by yCalleecharan
    Hi, I'm printing a variable say z1 which is a 1-D array containing floating point numbers to a text file so that I can import into Matlab or GNUPlot for plotting. I've heard that binary files (.dat) are smaller than .txt files. The definition that I currently use for printing to a .txt file is: void create_out_file(const char *file_name, const long double *z1, size_t z_size){ FILE *out; size_t i; if((out = _fsopen(file_name, "w+", _SH_DENYWR)) == NULL){ fprintf(stderr, "***> Open error on output file %s", file_name); exit(-1); } for(i = 0; i < z_size; i++) fprintf(out, "%.16Le\n", z1[i]); fclose(out); } I have three questions: Are binary files really more compact than text files?; If yes, I would like to know how to modify the above code so that I can print the values of the array z1 to a binary file. I've read that fprintf has to be replaced with fwrite. My output file say dodo.dat should contain the values of array z1 with one floating number per line. I have %.16Le up in my code but I think that %.15Le is right as I have 15 precision digits with long double. I have put a dot (.) in the width position as I believe that this allows expansion to an arbitrary field to hold the desired number. Am I right? As an example with %.16Le, I can have an output like 1.0047914240730432e-002 which gives me 16 precision digits and the width of the field has the right width to display the number correctly. Is placing a dot (.) in the width position instead of a width value a good practice? Thanks a lot...

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  • How to update application files using patching?

    - by Marek
    I am not interested in any auto update solution, such as ClickOnce or the MS Updater Block. For anyone feeling the urge to ask why not: I am already using these and there is nothing wrong with them, I would just like to learn about any efficient alternatives. I would like to publish patches = small differences that will modify existing files of the deployment with the smallest possible delta. Not only code needs to be patched, but also resource files. Patching the running code can be accomplished by maintaining two separate synchronized copies of the deployment (no on the fly changes to the running executable are required). The application itself can be xcopy deployed (to avoid MSI auto-correcting the modified files or breaking ClickOnce signatures). I would like to learn how to handle different versions of patches (e.g. there is a patch issued that fixes one error and later another patch that fixes another error (in the same file) - users may have any combination of these and there comes a third patch - in text files, this may be easy to implement, but how about executable files? (native Win32 code vs. .NET, any difference?) If the first problem is too hard to solve or unsolvable for executables, I would like to at least learn if there is a solution that implements simple patching with serial revisions - in order to install revision 5, user must have all previous revisions installed to ensure validity of the deployment. Are there any existing solutions to accomplish this? NOTE: There are a few questions on SO that may seem like duplicates, but none with a good answer. This question is about the Windows platform, preferably .NET.

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  • Single developer, project organization

    - by poke
    I am looking for a good (and free) way to organize some of my personal projects. I am saying "organize" because I'm not sure, if the standard project management software solutions are exactly what I am looking for and especially something what I, as a single developer, need. In general, I just want to keep my progress of my projects organized in some way. I would like to be able to keep track of milestones and split those into multiple smaller tasks, so I can keep track of my progress. So some task/issue based system would probably be good, especially as I also want to keep track of issues/bugs with specific versions (although I alone will create those issues). I am and will be the only developer on those projects, so it doesn't matter if the software is offline or online, and I also don't need any collaboration features (like commenting on things, or assigning tasks to other developers etc). But if there is a good software that fits my needs, and in addition it has those things, I don't really care. After all it's easy enough to not use available features. Many online solutions also offer integrated code hosting. I am using git internally, but I don't plan to push any of the code, so such a feature is not needed either. In case of online solutions however I would like the projects to be closed to the public (some of the online utilities only offer open source projects for free and require payments for private projects). I have looked at some project management solutions already, I also read some similar questions here on SO. But given that I'm a single developer, my focus is probably a bit different as when others ask for a huge distributed software that supports many developers and different collaboration features. Some standard answers such as Trac (which also only supports one project), Redmine and FogBUGZ look interesting, but are a bit off my interest (although you may change my mind on that :P). Currently, I'm looking at Indefero which doesn't look too bad. But what do you think?

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