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  • When are C++ macros beneficial?

    - by Motti
    The C preprocessor is justifiably feared and shunned by the C++ community. In-lined functions, consts and templates are usually a safer and superior alternative to a #define. The following macro: #define SUCCEEDED(hr) ((HRESULT)(hr) >= 0) is in no way superior to the type safe: inline bool succeeded(int hr) { return hr >= 0; } But macros do have their place, please list the uses you find for macros that you can't do without the preprocessor. Please put each use-cases in a seperate answer so it can be voted up and if you know of how to achieve one of the answers without the preprosessor point out how in that answer's comments.

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  • [PHP] Processing custom XML namespace within XSL

    - by sander
    I'm using the php class XSLTProcessor to generate HTML from a xsl. Within the xsl, I'd like all my custom namespace elements to be processed by my own processor class. So for example: <xsl:for-each select="doc/elements/*"> <doc:renderElement element="." /> </xsl:for-each> This should call the method renderElement of an instance of my custom processor class. I know I can enable calling php functions by using the registerPHPFunctions function. However, this only seems to support calling static methods.

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  • Unsigneds in order to prevent negative numbers

    - by Bruno Brant
    let's rope I can make this non-sujective Here's the thing: Sometimes, on fixed-typed languages, I restrict input on methods and functions to positive numbers by using the unsigned types, like unsigned int or unsigned double, etc. Most libraries, however, doesn't seem to think that way. Take C# string.Length. It's a integer, even though it can never be negative. Same goes for C/C++: sqrt input is an int or a double. I know there are reasons for this ... for example your argument might be read from a file and (no idea why) you may prefer to send the value directly to the function and check for errors latter (or use a try-catch block). So, I'm assuming that libraries are way better designed than my own code. So what are the reasons against using unsigned numbers to represent positive numbers? It's because of overflow when we cast then back to signed types?

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  • Do bit operations cause programs to run slower?

    - by flashnik
    I'm dealing with a problem which needs to work with a lot of data. Currently its values are represented as an unsigned int. I know that real values do not exceed a limit of 1000. Questions I can use unsigned short to store it. An upside to this is that it'll use less storage space to store the value. Will performance suffer? If I decided to store data as short but all the calling functions use int, it's recognized that I need to convert between these datatypes when storing or extracting values. Will performance suffer? Will the loss in performance be dramatic? If I decided to not use short but just 10 bits packed into an array of unsigned int. What will happen in this case comparing with previous ones?

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  • Generating code at compile-time using scripts

    - by Manux
    Hello, I would ideally like to be able to add (very repetitive) C/C++ code to my actual code, but at compile time, code which would come from say, the stdout of a python script, the same way one does with macros. For example, let's say I want to have functions that depend on the public attributes of a given class, being able to just write the following in my C++ code would be a blessing: generate_boring_functions(FooBarClass,"FooBarClass.cpp") Is that feasible using conventional means? Or must I hack with Makefiles and temporary source files? Thanks.

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  • Ways to optimize Android App code based on function call stack?

    - by K-RAN
    I've been told that Android OS stores all function calls in a stack. This can lead to many problems and cause the 'hiccups' during runtime, even if a program is functionalized properly, correct? So the question is, how can we prevent this from happening? The obvious solution is to functionalize less, along with other sensible acts such as refraining from excessively/needlessly creating objects, performing static calls to functions that don't access fields, etc... Is there another way though? Or can this only be done through careful code writing on the programmers' part? Does the JVM/JIT automatically optimize the bytecode during compile time to account for this?? Thanks a lot for your responses!!

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  • C# Dynamic From Components (Performance problem)

    - by Svisstack
    Hello, I have a problem with performance of my code under Windows Forms. Have a form, her layout is depending on constructor data, because he layout must be OnLoad or in Constructor generated. I generation is simple, base FlowLayoutPanel have other FlowLayoutPanels, for each have a Label and TextBox with DataBinding. Problem is this is VERY SLOW, up to 20 seconds, i drawing less than 100 controls, from Performace Session i know a problem is on 70% procesing functions: System.Windows.Forms.Control.ControlCollection.Add(class System.Windows.Forms.Control) System.Windows.Forms.ControlBindingsCollection.Add(class System.Windows.Forms.Binding) How i can do with this? Anyone help me in this problem? How solve the dynamic form layout problem?

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  • How can i convert between F# List and F# Tuple?

    - by ksharp
    Is there some way to convert between F# List and F# Tuple? For example: [1;2;3] -> (1,2,3) (1,2,3,4) -> [1;2;3;4] I need two Functions to do that: let listToTuple list = ... let tupleToList tuple = ... Thank you in advance. I think reflection is necessary to this problem. I know the performance is not good. I have to pay the cost of breaking functional programming rule.

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  • How can I (from a script) add something to the zsh command history?

    - by Brandon
    I'd like to be able to look through my command history and know the context from which I issued various commands--in other words, "what directory was I in?" There are various ways I could achieve this, but all of them (that I can think of) would require manipulating the zsh history to add (for instance) a commented line with the result of $(pwd). (I could create functions named cd & pushd & popd etc, or I could use zsh's preexec() function and maybe its periodic() function to add the comment line at most every X seconds, just before I issue a command, or perhaps there's some other way.) The problem is, I don't want to directly manipulate the history file and bypass the shell's history mechanism, but I can't figure out a way (with the fc command, for instance) to add something to the history without actually typing it on the command line. How could I do this?

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  • What is the use of reflection in Java/C# etc

    - by zengr
    I was just curious, why should we use reflection in the first place? // Without reflection Foo foo = new Foo(); foo.hello(); // With reflection Class cls = Class.forName("Foo"); Object foo = cls.newInstance(); Method method = cls.getMethod("hello", null); method.invoke(foo, null); We can simply create an object and call the class's method, but why do the same using forName, newInstance and getMthod functions? To make everything dynamic?

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  • javasrcipt asyncronous function

    - by Ben
    Hi there, i have a problem understanding how this could/should be solved. I have two functions. In the first function ( I call it loadData() ) I'm doing an asyncronous request to the server to load some data. In the second function ( saveData() ) I'm also doing an asyn request to the server to write some data. In the callback of this request I'm callin loadData() to refresh the data. Now the problem: In the saveData() function I want to wait for loadData() to be finished bevore I show a dialog (like alert('Data saved')) I guess this is a common problem, but I couldn't find the solution for it (if there is one..) A solution would be to make the requests syncronous, but the framework I'm using doesn't offer that and I hope there's a better solution.. Thanks to all!

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  • How should I get the value contained in a particular field of a Drupal 7 custom node?

    - by Matt V.
    What is the "proper" way to get the value stored in a particular field within a custom Drupal node? I've created a custom module, with a custom node, with a custom URL field. The following works: $result = db_query("SELECT nid FROM {node} WHERE title = :title AND type = :type", array( ':title' => $title, ':type' => 'custom', ))->fetchField(); $node = node_load($result); $url = $node->url['und']['0']['value']; ...but is there a better way, maybe using the new Field API functions?

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  • Enter purchase order received quantity by code

    - by user733916
    In purchase order form - Line - Tab Quantity, there is Received, Delivery Reminder and Ordered. I want to be able to entry those field by X++ code, because currently our company still entry data into old system. I can retrieve the arrival purchase order goods data from that old system, then I want to entry those retrieved data by code into Axapta. What table and field should I consider when doing that? What functions available to easily update each PO lines received quantity? Sample Code is nice.

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  • Is it possible get the functionality of namespaces inside a class?

    - by CowKingDeluxe
    I have the following code: Public Class Form1 Private Function Step1_Execute() As Boolean Return Step1_Verify() End Function Private Function Step1_Verify() As Boolean Return True End Function Private Function Step2_Execute() As Boolean Return Step2_Verify() End Function Private Function Step2_Verify() As Boolean Return True End Function End Class What I would like to do is be able to separate the code, similar to the following (which obviously doesn't work): Public Class Form1 Namespace Step1 Private Function Step1_Execute() As Boolean Return Step1_Verify() End Function Private Function Step1_Verify() As Boolean Return True End Function End Namespace Namespace Step2 Private Function Step2_Execute() As Boolean Return Step2_Verify() End Function Private Function Step2_Verify() As Boolean Return True End Function End Namespace End Class I would like the functionality of namespaces inside of a class, as in something that would let me call Step2.Execute() instead of having to put Step2_ in front of a whole bunch of functions. I don't want to have to create separate classes / modules for step1, step2, etc. Is there a way that I can accomplish namespace functionality from inside a class?

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  • C++ setTimout function ?

    - by Quandary
    What's the cheapest way for a JavaScript like setTimeout-function in C++? I would need this: 5000 miliseconds from now, start function xy (no parameters, no return value). The reason for this is I need to initialize COM for text to speech, but when I do it on dll attach, it crashes. It works fine however if I do not call CoInitialize from dllmain. I just need to call CoInitialize and CoCreateInstance, and then use the instance in other functions. I can catch the uninitialized instance by checking for NULL, but I need to initialize COM - without crashing.

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  • GNUPlot: plot different ranges with different styles

    - by Mr. Shickadance
    Hello all, I know this should be pretty simple, but I haven't been able to find a similar example. I need to plot different ranges of a datafile differently, but on the same graph. For instance, say my datafile represents a function with x and y values. I want to plot the first N values using a style like lines, and then the next M values using a different style, like points. I was thinking I would need a plot command similar to this: plot [1:5] "my.data" using 1:2 with lines, [6:12] using 1:2 with points, [13:19] using 1:2 with lines Essentially I want to distinguish different areas of the functions. Any ideas? I am sorry if it sounds like I'm rambling but I am quite stumped. Thanks in advance!

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  • jQuery version of YAHOO.lang (isUndefined, isNull, isString etc.)

    - by Chris S
    Does anyone know of a jQuery plugin that has 'helpers' or extensions like those found in the YAHOO.lang namespace? I have in mind functions such as: isNull isDefined isString isFunction I would also appreciate the same kind of thing for strings and arrays, such as Contains, StartsWith (I know these are easy to write, I'm just looking for a plugin that encompasses them all). It's not in the YAHOO.lang namespace but also form related extensions- determining a radiobox's value (from the one checked), a form element's type in a friendly name. Specifically a plugin with fluent API rather than selector based such as $("input[@type=radio][@checked]") Again I'm aware they're easy to implement but I don't want to reinvent the wheel.

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  • Are there any context-sensitive code search tools?

    - by Vicky
    I have been getting very frustrated recently in dealing with a massive bulk of legacy code which I am trying to get familiar with. Say I try to search for a particular function call, I get loads of results that turn out to be completely irrelevant; some of them are easy to spot, eg a comment saying // Fixed functionality in foo() so don't need to handle this here any more But others are much harder to spot manually, because they turn out to be calls from other functions in modules that are only compiled in certain cases, or are part of a much larger block of code that is #if 0'd out in its entirety. What I'd like would be a search tool that would allow me to search for a term and give me the choice to include or exclude commented out or #if 0'd out code. Then the search results would be displayed alongside a list of #defines that are required in order for that snippet of code to be relevant. I'm working in C / C++, but other than the specific comment syntax I guess the techniques should be more generally applicable. Does such a tool exist?

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  • How to maipulate the shell output in php

    - by Mirage
    I am trying to write php script which does some shell functions like reporting. So i am starting with diskusage report I want in following format drive path ------------total-size --------free-space Nothing else My script is $output = shell_exec('df -h -T'); echo "<pre>$output</pre>"; and its ouput is like below Filesystem Type Size Used Avail Use% Mounted on /dev/sda6 ext3 92G 6.6G 81G 8% / none devtmpfs 3.9G 216K 3.9G 1% /dev none tmpfs 4.0G 176K 4.0G 1% /dev/shm none tmpfs 4.0G 1.1M 4.0G 1% /var/run none tmpfs 4.0G 0 4.0G 0% /var/lock none tmpfs 4.0G 0 4.0G 0% /lib/init/rw /dev/sdb1 ext3 459G 232G 204G 54% /media/Server /dev/sdb2 fuseblk 466G 254G 212G 55% /media/BACKUPS /dev/sda5 fuseblk 738G 243G 495G 33% /media/virtual_machines How can i convert that ouput into my forn\matted output

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  • Whats the API Key for in Google Maps API V3?

    - by Brandon
    In the older version of the API, I'd have to insert the javascript into the page using something like this for just basic functionality to work: http://maps.google.com/maps?file=api&v=2&key=GoogleMapsAPIKey Where I had to configure the API key for each individual site. Looking at the documentation, it says to get a basic map working I just need this: http://maps.google.com/maps/api/js?sensor=true/false Where does the API key fit in? Do I need to worry about it if I just plan on using a basic map and marker and none of the more advanced functions?

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  • namespacing large javascript like jquery

    - by frenchie
    I have a very large javascript file: it's over 9,000 lines. The code looks like this: var GlobalVar1 = ""; var GlobalVar2 = null; function A() {...} function B(SomeParameter) {...} I'm using the google compiler and the global variables and functions get renamed a,b,c... and there's a good change that there might be some collision later with some outside code. What I want to do is have my code organized like the jquery library where everything is accessible with $. Is there a way to namespace my code so that everything is behind a # character for example. I'd like to have this to call my code: #.GlobalVar #.functionA(SomeParameter) How can I do this? Thanks.

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  • Function calls in virtual machine killing performance

    - by GenTiradentes
    I wrote a virtual machine in C, which has a call table populated by pointers to functions that provide the functionality of the VM's opcodes. When the virtual machine is run, it first interprets a program, creating an array of indexes corresponding to the appropriate function in the call table for the opcode provided. It then loops through the array, calling each function until it reaches the end. Each instruction is extremely small, typically one line. Perfect for inlining. The problem is that the compiler doesn't know when any of the virtual machine's instructions are going to be called, as it's decided at runtime, so it can't inline them. The overhead of function calls and argument passing is killing the performance of my VM. Any ideas on how to get around this?

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  • Clean way in GWT/Java to wait for multiple asynchronous events to finish

    - by gerdemb
    What is the best way to wait for multiple asynchronous callback functions to finish in Java before continuing. Specifically I'm using GWT with AsyncCallback, but I think this is a generic problem. Here's what I have now, but surely there is cleaner way... AjaxLoader.loadApi("books", "0", new Runnable(){ public void run() { bookAPIAvailable = true; ready(); }}, null); AjaxLoader.loadApi("search", "1", new Runnable(){ public void run() { searchAPIAvailable = true; ready(); }}, null); loginService.login(GWT.getHostPageBaseURL(), new AsyncCallback<LoginInfo>() { public void onSuccess(LoginInfo result) { appLoaded = true; ready(); } }); private void ready() { if(bookAPIAvailable && searchAPIAvailable && appLoaded) { // Everything loaded } }

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  • PHP Global variable in class is reset

    - by Robert
    I have a web form that manipulates records in a MySQL database. I have a method for displaying an edit interface for both creating new records and editing them if ($_POST['new_page']) { print "<h2>Create new page</h2>\n"; $isNew=1; $this->EditForm(); } else if($_POST['edit']){ print "<h2>Edit page</h2>\n"; $isNew=0; $this->EditForm(); } I am trying to use the global variable $isNew to determine where a record is to be added or updated. However, whenever my SaveChanges() function is run, $isNew is always 0. $isNew is declared immediately after the class declaration, outside all of the functions. class Editor{ public $isNew;

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  • how to call a javascript function in the top frame?

    - by Rory
    This seems really simple, but how do I call a javascript function that's defined in the top-level html, from a child frame? top html doc - 1st level frame - 2nd level frame my top html doc has a function called testFn(). In the 2nd level frame I have a button with onclick="top.testFn();" but this doesn't call the testFn(). In Firebug if I use a watch to execute top.testFn(); it says TypeError: testFn() is not a function. Should this all just work - in which case it's a problem with my documents, or is there some other way to call functions in the top-level window?

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