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  • Why does the assignment operator return a value and not a reference?

    - by Nick Lowman
    I saw the example below explained on this site and thought both answers would be 20 and not the 10 that is returned. He wrote that both the comma and assignment returns a value, not a reference. I don't quite understand what that means. I understand it in relation to passing variables into functions or methods i.e primitive types are passed in by value and objects by reference but I'm not sure how it applies in this case. I also understand about context and the value of 'this' (after help from stackoverflow) but I thought in both cases I would still be invoking it as a method, foo.bar() which would mean foo is the context but it seems both result in a function call bar(). Why is that and what does it all mean? var x = 10; var foo = { x: 20, bar: function () {return this.x;} }; (foo.bar = foo.bar)();//returns 10 (foo.bar, foo.bar)();//returns 10

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  • Should I convert data arrays to objects in PHP in a CouchDB/Ajax app?

    - by karlthorwald
    I find myself converting between array and object all the time in PHP application that uses couchDB and Ajax. Of course I am also converting objects to JSON and back (for sometimes couchdb but mostly Ajax), but this is not so much disturbing my workflow. At the present I have php objects that are returned by the CouchDB modules I use and on the other hand I have the old habbit to return arrays like array("error"="not found","data"=$dataObj) from my functions. This leads to a mixed occurence of real php objects and nested arrays and I cast with (object) or (array) if necessary. The worst thing is that I know more or less by heart what a function returns, but not what type (array or object), so I often run into type errors. My plan is now to always cast arrays to objects before returning from a function. Of course this implies a lot of refactoring. Is this the right way to go? What about the conversion overhead? Other ideas or tips?

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  • What is the smallest Windows header I can #include to define DWORD?

    - by j_random_hacker
    I have a small header file of my own which declares a couple of functions, one of which has a return type of DWORD. I'm reluctant to drag in windows.h just to get the official definition of this type since that file is huge, and my header will be used in a number of source modules that don't otherwise need it. Of course, in practice I know that DWORD is just unsigned int, but I'd prefer the more hygienic approach of including an official header file if possible. On this page it says that DWORD is defined in windef.h, but unfortunately including just this small file directly leads to compilation errors -- apparently it expects to be included by other headers. (Also, the fact that my file is a header file also means I can't just declare WIN32_LEAN_AND_MEAN, since the source file that #includes my file might need this to be left undefined.) Any ideas? I know it's not the end of the world -- I can just continue to #include <windows.h> -- but thought someone might have a better idea!

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  • Assign grid.arrange to object

    - by Tyler Rinker
    I want to arrange plots with grid.arrange to make more complex coplots and then use grid.arrange to combine these complex coplots. I am using the following solution (http://stackoverflow.com/a/13295880/1000343) in this task to arrange mutliple plots and ensure they have equal widths. Here is a demo of the code: library(ggplot2); library(gridExtra) gA <- ggplotGrob(A) gB <- ggplotGrob(B) maxWidth = grid::unit.pmax(gA$widths[2:5], gB$widths[2:5]) gA$widths[2:5] <- as.list(maxWidth) gB$widths[2:5] <- as.list(maxWidth) x <- grid.arrange(gA, gB, ncol=1) y <- grid.arrange(gA, gB, ncol=1) grid.arrange(x, y, ncol=2) To be clear in my case x and y are slightly different plots with different values. I know grid.arrange isn't returning the plot as other grid based functions.

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  • How to keep the first result of a function from Prolog?

    - by zuhakasa
    I need to write a customized function that will be called many times by other fixed functions. In this function, at the first called time, it will return the total number of lines of a file. The second called time of this function, forward, will return the number of lines in small sections of this file. My question is how I keep the first returned result(total number of lines of a file) and use it for the next called times of my function. I need to write or declare any thing only in this function(not in the caller). Something like this: myFunction(Input, MyResult, FirstResult) :- calculateInputFunction(Input, Result), !, MyResult is Result, ... . The problem is, every time myFunction is called, it receives different Input and returns different MyResult. But I would like to keep the first MyResult to use for next called times of myFunction. How can I do that? Thanks very much for your answer in advance.

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  • Emacs and Long Shell Commands

    - by darrint
    Is there a way to run a shell command, have the output show up in a new buffer and have that output show up incrementally? Eshell and other emacs terminal emulators do a find job of this but I see no way to script them. What I'd like to do is write little elisp functions to do stuff like run unit tests, etc. and watch the output trickle into a buffer. The elisp function shell-command is close to what I want but it shows all the output at once when the process finishes.

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  • MySQL Integer vs DateTime index

    - by David Kuridža
    Let me start by saying I have looked at many similar questions asked, but all of them relate to Timestamp and DateTime field type without indexing. At least that is my understanding. As we all know, there are certain advantages when it comes to DateTime. Putting them aside for a minute, and assuming table's engine is InnoDB with 10+ million records, which query would perform faster when criteria is based on: DateTime with index int with index In other words, it is better to store date and time as DateTime or UNIX timestamp in int? Keep in mind there is no need for any built-in MySQL functions to be used.

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  • Getting imagename and make link from <img> with jQuery

    - by Bulan
    With jQuery, I want to make all images under a specific path on a site clickable and showing a big image using Fancybox, which is a lighbox variant plugin for jQuery. My small images are located under "images/products/small", the big ones under "images/products/big" and the imagename is always the same The page is showing the image with the following code: <img src="images/products/small/hat.jpg" alt="Nice hat"> What i want is some jQuery script that makes this into: <a href="images/products/big/hat.jpg" class="fancybox"><img src="images/products/small/hat.jpg" alt="Nice hat"></a> Maybe the part with setting class on the link tag can be skipped and just activate fancybox on the element directly with $(elm).fancybox(); I was looking around a bit and it looks like the jQuery functions "attr" and "wrap" might be useful, but with my currently limited jQuery skills I can't really connect the dots.

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  • Looking for a standard way to manage documents in a WPF application

    - by user322383
    Hi! I'm writing a WPF application that uses one document at a time. Is there any standard way to implement the management of the current document? What I mean are the following functions: New document: if there are not saved changes in the current document, a dialog box opens ('Do you want to save changes to {0}?') with Yes/No/Cancel buttons. If Cancel is hit, the operation stops. Open document: same dialog box as at new document, and an Open dialog opens after Save document: if the current document hasn't been saved, a Save dialog opens Save as: you can imagine... So, is there anything standard in the .NET framework like this or do I have to manually implement it?

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  • Is pthread_spin_trylock safe inside of sigsegv handler of multithreaded application?

    - by TWMouton
    I am trying to implement a handler that on SIGSEGV will collect some information such as process-id, thread-id and a backtrace and write this information to a file/pipe/socket. The problem lies in that there is the (probably pretty high) possibility that if one thread experienced a SIGSEGV that the others will shortly follow. If two threads happen to make it to the bit of code where they're writing their report out at the same time then they'll interleave their writing (to the same file). I know that I should only be using async-signal-safe functions as detailed in signal(7) I also have seen at least two cases here and video linked in top answer here where others have used pthread_spin_trylock to get around this problem. Is this a safe way to prevent the above problem?

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  • How should I use try...except while defining a function?

    - by SpawnCxy
    Hi all, I find I've been confused by the problem that when I needn't to use try..except.For last few days it was used in almost every function I defined which I think maybe a bad practice.For example: class mongodb(object): def getRecords(self,tname,conditions=''): try: col = eval("self.db.%s" %tname) recs = col.find(condition) return recs except Exception,e: #here make some error log with e.message What I thought is ,exceptions may be raised everywhere and I have to use try to get them. And my question is,is it a good practice to use it everywhere when defining functions?If not are there any principles for it?Help would be appreciated! Regards

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  • How to change the value of progressbar in C#?

    - by shekhar
    Hi, I want to add an progress bar into my C# based application. I would like to know what is the good way of updating its value at particular events? My problem is, I have single function in UI which does all the processing.This function in turn calls many more functions, creates objects, updates database, etc. (basically performs all the work) and returns values in an output file. I have access to that function only. So in this how to update the progressbar's value at the end of each step? What is the best practice for this kind of situation? What is the good way to keep UI logic and business logic seperate? I want to avoid writting progressbar related code in my library code. Please suggest some solution. Thanks and Regards,

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  • Calling C++ function from C.

    - by claws
    I know this. Calling C function from C++: If my application was in C++ and I had to call functions from a library written in C. Then I would have used //main.cpp extern "C" void C_library_function(int x, int y);//prototype C_library_function(2,4);// directly using it. This wouldn't mangle the name C_library_function and linker would find the same name in its input *.lib files and problem is solved. Calling C++ function from C??? But here I'm extending a large application which is written in C and I need to use a library which is written in C++. Name mangling of C++ is causing trouble here. Well I cannot use C++ compiler over my C project because thats breaking lot of other stuff. What is the way out? By the way I'm using MSVC

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  • What is the precedence of characters when sorting in MySQL, PHP, or just in general?

    - by FireCoding
    Question: Where can I find the precedence of characters when sorting in MySQL, PHP, or just in general on Linux and Windows OS? For example, everybody knows that a comes before b when performing an ascending sort on a string in MySQL. But what about other characters? Does the dollar-sign $ come before asterisk * ? Does a space come before an exclamation-mark? etc... What dictates the sort order? Does it use underlying ascii / UTF-8 values? Is it different for different technologies? Technologies to consider: Databases - MySQL / SQL / SQLite / Oracle / etc Programming languages (for string-sorting functions) - PHP / Javascript / ASP.NET / Visual C# / Python / Ruby / Objective C OS (i.e., sorting files by filename) - Windows / Linux / MacOS / iOS / Android

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  • how to use replace_regex_copy() from boost::algorithm library?

    - by Vincenzo
    This is my code: #include <string> #include <boost/algorithm/string/regex.hpp> string f(const string& s) { using namespace boost::algorithm; return replace_regex_copy(s, "\\w", "?"); } This is what compiler says: no matching function for call to ‘replace_regex_copy(const std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, std::string, std::string) The link to the library: http://www.boost.org/doc/libs/1_43_0/doc/html/boost/algorithm/replace_regex_copy.html Could anyone please help? Thanks! ps. Boost library is in place, since other functions from it work fine.

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  • MySQL LEFT JOIN issue with three WHERE statements

    - by jhat
    I am building a note taking app for myself with tag filtering functions, but am having an issue when trying to grab notes with the tags. The tag filter needs to use AND not IN, because it will help better narrow down what I am looking for. My tables are configured like this: + notes note_id | note_title | note_uid + tags tag_id | tag_title + notes_tags nt_id | nt_note_id | nt_tag_id The notes_tags table keeps track of all notes' tags. I am not worried about returning any information about tags, so here is an example LEFT JOIN I am using currently to only get notes with only 1 tag. SELECT * FROM notes_tags LEFT JOIN notes ON note_id = nt_note_id WHERE note_uid IN ( 1 ) AND nt_tag_id = 10 This query runs perfect, it grabs all of the notes with that single tag. However, I am having issues "pinpointing" my notes using a query like this: SELECT * FROM notes_tags LEFT JOIN notes ON note_id = nt_note_id WHERE note_uid IN ( 1 ) AND nt_tag_id = 10 AND nt_tag_id = 11 What am I doing wrong with the syntax?

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  • Changing the way widgets are rendered/displayed in a form on the template

    - by user334017
    I have a form with a few other embedded forms and some various widgets. The widgets are all saved in an array $form['elements'] and for some of them, I want to display labels and things, but for others I only want to display the basic rendering. foreach($form['elements'] as $elem) echo $elem->render(); this displays everything about the widget. The way it is right now, I couldn't for example call $elem['..'] because the different subforms appear in a random order and have different variable names. I assume I could still put some checks in the template, but it seems easier to fix this in the widget class, like override one of the render functions or something. How would I go about doing this or do you have any links that could help me understand how do do this? on a side note, one of my widgets is the sfWidgetFormChoice and I have no clue where it actually renders or how renderer_classes work

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  • Function to set an auth_token

    - by john mossel
    In my form I have a hidden field: <input type="hidden" name="auth_token" value="<?php echo $auth_token; ?>"> This value is also stored in a session and a variable: $_SESSION['auth_token'] = hash('sha256', rand() . time() . $_SERVER['HTTP_USER_AGENT']); # TODO: put this in a function $auth_token = $_SESSION['auth_token']; When the form is submitted the two values are compared. It's a basic form token. Should this be made into two functions or just one when refactored? set_form_token() and get_form_token(), get_form_token() returning the session value, then I can compare it in my main code. What is the proper way of doing this?

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  • [FLEX 3] Placing images into a Collage Canvas

    - by Bridget
    I've got an array of different sized images. I want to place these images on a canvas in a sort of automated collage. Does anyone have an idea of how to work the logic behind this concept? All my images have heights divisible by 36 pixels and widths divisible by 9 pixels. They have mouseDown functions that allow you to drag and drop. When dropped the image goes to the closest x point divisible by 9 and y point divisble by 36. There is a grid drawn on top of the canvas. I've sorted the array of images based on height, then based on their widths. imagesArray.sortOn("height", Array.NUMERIC | Array.DESCENDING); imagesArray.sortOn("width", Array.NUMERIC | Array.DESCENDING); I'd like to take the largest image ( imageArray[0] ) to put in corner x,y = 0,0. Then randomize the rest of the images and fit them into the collage canvas.

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  • F# - Function with no arguments?

    - by Rubys
    When thinking in a functional mindset, given that functions are supposed to be pure, one can conclude any function with no arguments is basically just a value. However, reallity gets in the way, and with different inputs, I might not need a certain function, and if that function is computationally expensive, I'd like to not evaluate it if it's not needed. I found a workaround, using let func _ = ... and calling it with func 1 or whatever, but that feels very non-idiomatic and confusing to the reader. This boils down to one question: In F#, Is there a proper way to declare a function with zero arguments, without having it evaluated on declaration?

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  • Elegant way to distinct Path or Entry key

    - by sum1stolemyname
    I have an application loading CAD data (Custom format), either from the local filesystem specifing an absolute path to a drawing or from a database. Database access is realized through a library function taking the drawings identifier as a parameter. the identifiers have a format like ABC 01234T56-T, while my paths a typical windows Paths (eg x:\Data\cadfiles\cadfile001.bin). I would like to write a wrapper function Taking a String as an argument which can be either a path or an identifier which calls the appropriate functions to load my data. Like this: Function CadLoader(nameOrPath : String):TCadData; My Question: How can I elegantly decide wether my string is an idnetifier or a Path to a file? Use A regexp? Or just search for '\' and ':', which are not appearing in the Identifiers?

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  • Call inner function of jQuery-Plugin-function?

    - by faileN
    Hello Everyone, I've written an jQuery-Plugin, which I want to use as Object. So I declared some functions within the plugin, which I want to call from any other location, just like an object with methods. Is that even possible? To keep it simple: (function( $ ){ $.fn.myPlugin = function(){ // Here I want methods... function foo() { // do something... } } })(jQuery); Then I want to call the inner function from outside the plugin like: $.myPlugin.foo(); But that doesn't seem to work. So is it even possible? Or are there any other solutions? I don't want to use an normal unrelated jQuery-Class for this purpose. Because this plugin should work together with some other jQuery-Plugins. Thank you

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  • OpenGL ES perspective projection

    - by TimeManx
    I'm having a hard time understanding how glFrustum & gluPerspective work. I understand the concept of perspective projection but the functions aren't behaving how I expect them to. For example, if I set the frustum this way glFrustumf(0, 10, 0, 10, 1, 100) and have a rectangle at points 0, 0, 1, 0, 10, 1, 10, 10, 1, 10, 0, 1 then the rectangle is drawn with its left edge at -5 & right edge at 5, so the left half of the rectangle isn't visible. And if x is translated, I'd expect y to be too. But that doesn't happen either. In whatever examples I've seen, the coordinates for the projection matrix are taken as glFrustumf(-10, 10, -10, 10, 1, 100) but either way, whatever part is shown should be dependent on the rectangle's coordinates, right?

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  • How to pass multiple params to function in python?

    - by user1322731
    I am implementing 8bit adder in python. Here is the adder function definition: def add8(a0,a1,a2,a3,a4,a5,a6,a7,b0,b1,b2,b3,b4,b5,b6,b7,c0): All function parameters are boolean. I have implemented function that converts int into binary: def intTObin8(num): bits = [False]*8 i = 7 while num >= 1: if num % 2 == 1: bits[i] = True else: bits[i] = False i = i - 1 num /= 2 print bits return [bits[x] for x in range(0,8)] I want this function to return 8 bits. And to use this two functions as follows: add8(intTObin8(1),intTObin8(1),0) So the question is: How to pass 8 parameters using one function?

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  • time(NULL) returning different time

    - by cornerback84
    I am trying to get current time in C using time_t current_time = time(NULL). As I understand, it would return me the current time of system. I am later trying to convert it into GMT time using struct tm* gmt = gmtime(&current_time). I print both times using ctime() and asctime() functions. The current time on my system is GMT + 1. But gmtime() returns me the same time as current_time is. I could not understand why gmtime() is returning me same time. Any help will be appreciated.

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