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• Any way in C++ to forward declare a function prototype?

  - by jsyjr

  I make regular use of forward class declarations and pointers to such classes. I now have a need to pass a function pointer through a number of layers. I would prefer to include the header that declares my function pointer's prototype only into the module that dereferences a function pointer rather than into each layer that simply passes along that pointer value. Is this possible?

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• C - What is the proper format to allow a function to show an error was encountered?

  - by BrainSteel

  I have a question about what a function should do if the arguments to said function don't line up quite right, through no fault of the function call. Since that sentence doesn't make much sense, I'll offer my current issue. To keep it simple, here is the most relevant and basic function I have. float getYValueAt(float x, PHYS_Line line, unsigned short* error) *error = 0; if(x < line.start.x || x > line.end.x){ *error = 1; return -1; } if(line.slope.value != 0){ //line's equation: y - line.start.y = line.slope.value(x - line.start.x) return line.slope.value * (x - line.start.x) + line.start.y; } else if(line.slope.denom == 0){ if(line.start.x == x) return line.start.y; else{ *error = 1; return -1; } } else if(line.slope.num == 0){ return line.start.y; } } The function attempts to find the point on a line, given a certain x value. However, under some circumstances, this may not be possible. For example, on the line x = 3, if 5 is passed as a value, we would have a problem. Another problem arises if the chosen x value is not within the interval the line is on. For this, I included the error pointer. Given this format, a function call could work as follows: void foo(PHYS_Line some_line){ unsigned short error = 0; float y = getYValueAt(5, some_line, &error); if(error) fooey(); else do_something_with_y(y); } My question pertains to the error. Note that the value returned is allowed to be negative. Returning -1 does not ensure that an error has occurred. I know that it is sometimes preferred to use the following method to track an error: float* getYValueAt(float x, PHYS_Line line); and then return NULL if an error occurs, but I believe this requires dynamic memory allocation, which seems even less sightly than the solution I was using. So, what is standard practice for an error occurring?

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• [PHP] How to pass array as multiple parameters to function?

  - by vbklv

  I have a parameters array: $params[1] = 'param1'; $params[2] = 'param2'; $params[3] = 'param3'; ... $params[N] = 'paramN'; I have a caller to various functions: $method->$function( $params ); How can I parse the $params array, so multiple (and unlimited) parameters can be passed to any function: $method->$function( $param[1], $param[2], ..., $param[N] );

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• PHP Magic methods not working

  - by user991047

  I am trying to create a registry class with magic __set and __get my class looks like class Registry { private $vars = array(); public function __set($key, $value) { $this->vars[$key] = $value; dump($key, $value); } public function __get($index) { $this->vars[$index]; } } but if i try to save some variable in registry class in gets only the $key the $value is alway NULL. here is the sample code how I am try to call this class $registry = new registry; $registry->router = $router; $registry->title = "Welcome ";

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• How to create a function and pass in variable length argument list?

  - by Jian Lin

  We can create a function p in the following code: var p = function() { }; if (typeof(console) != 'undefined' && console.log) { p = function() { console.log(arguments); }; } but the arguments are passed like an array to console.log, instead of passed one by one as in console.log(arguments[0], arguments[1], arguments[2], ... Is there a way to expand the arguments and pass to console.log like the way above? Note that if the original code were var p = function() { }; if (typeof(console) != 'undefined' && console.log) { p = console.log; } then it works well on Firefox and IE 8 but not on Chrome.

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• Reference table values in a war against magic numbers

  - by Alex N.

  This question bugged me for years now and can't seem to find good solution still. I working in PHP and Java but it sounds like this maybe language-agnostic :) Say we have a standard status reference table that holds status ids for some kind of entity. Further let's assume the table will have just 5 values, and will remain like this for a long time, maybe edited occasionally with addition of a new status. When you fetch a row and need to see what status it is you have 2 options(as I see it at least) - put it straight ID values(magic numbers that is) or use a named constant. Latter seem much cleaner, the question though is where those named constants should leave? In a model class? In a class that uses this particular constant? Somewhere else?

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• jquery - How to reference two div elements for a single function?

  - by Ben

  I Have a function that references a specific input text box. I would like to extend the function to be used by two specific input text boxes. Rather than duplicate the code for the other text box, can anyone advise on how to reference the other? Here it uses #Tags, but if i wanted it to reference #Tags2 also, how could I do that? $(function () { $('#Tags').tagSuggest({ separator: ", ", tagContainer: 'div', tags: ["tag1","tag2"] }); });

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• how to .call() on the unnamed function in javascript?

  - by Anonymous

  Let's suppose I have button #click, And suppose I bind the on click event as follows: $('#click').click(function(){ alert('own you'+'whatever'+$(this).attr('href')); }); But I want this to refer to some other element, let's say #ahref. If it was a named function I would simply refer it by name: foo.call('#ahref'); How could I use .call() though, if the function is called inline and does not have a name?

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• Haskell: How to compose `not` with a function of arbitrary arity?

  - by Hynek -Pichi- Vychodil

  When I have some function of type like f :: (Ord a) => a -> a -> Bool f a b = a > b I should like make function which wrap this function with not. e.g. make function like this g :: (Ord a) => a -> a -> Bool g a b = not $ f a b I can make combinator like n f = (\a -> \b -> not $ f a b) But I don't know how. *Main> let n f = (\a -> \b -> not $ f a b) n :: (t -> t1 -> Bool) -> t -> t1 -> Bool Main> :t n f n f :: (Ord t) => t -> t -> Bool *Main> let g = n f g :: () -> () -> Bool What am I doing wrong? And bonus question how I can do this for function with more and lest parameters e.g. t -> Bool t -> t1 -> Bool t -> t1 -> t2 -> Bool t -> t1 -> t2 -> t3 -> Bool

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• How to declare a pointer to a variable as a parameter of a function in C++?

  - by Keand64

  I have a function that takes a pointer to a D3DXVECTOR3, but I have no reason to declare this beforehand. The most logical solution to me was using new: Function( //other parameters, new D3DXVECTOR3(x, y, 0)); but I don't know how I would go about deleting it, beign intitialized in a function. My next thought was to use the & operator, like so: Function( //other parameters, &D3DVECTOR3(x, y, 0)); but I don't know if this is a valid way to go about doing this. (It doesn't get an error, but neither does int *x; x = 50;). So should I use new, &, or some other technique I'm overlooking?

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• How to make a function retun after 5 second passes in python?

  - by alwbtc

  I want to write a function which will return after 5 seconds no matter what: def myfunction(): while passed_time < 5_seconds: do1() do2() do3() . . return I mean, this function run for 5 seconds only, after 5 seconds, it should end, and continue with other function: myfunction() otherfunction() ----> This should start 5 seconds after myfunction() is executed. Best Regards

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• Get a list/tuple/dict of *all* the arguments passed to a function?

  - by Phillip Oldham

  Given the following function: def foo(a, b, c): pass How would one obtain a list/tuple/dict/etc of the arguments passed in? Specifically, I'm looking for Python's version of JavaScript's arguments keyword or PHP's func_get_args() method. What I'm not looking for is a solution using *args or **kwargs; I need to specify the argument names in the function definition (to ensure they're being passed in) but within the function I want to work with them in a list- or dict-style structure.

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• PHP: Collect all variables passed to a function as array?

  - by Industrial

  Hi everybody, I was thinking about the possibility of accessing all the variables that are passed into an function, and merge them into an array. (Without passing variables into an array from the beginning) Pseudo-code: // Call function newFunction('one', 'two', 'three' ) ;// All values are interpreted as a one rray in some way // Function layout newFunction( ) { // $functionvariables = array( All passed variables) foreach ($functionvariable as $k => $v) { // Do stuff } }

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• SQL SERVER – Introduction to PERCENTILE_CONT() – Analytic Functions Introduced in SQL Server 2012

  - by pinaldave

  SQL Server 2012 introduces new analytical function PERCENTILE_CONT(). The book online gives following definition of this function: Computes a specific percentile for sorted values in an entire rowset or within distinct partitions of a rowset in Microsoft SQL Server 2012 Release Candidate 0 (RC 0). For a given percentile value P, PERCENTILE_DISC sorts the values of the expression in the ORDER BY clause and returns the value with the smallest CUME_DIST value (with respect to the same sort specification) that is greater than or equal to P. If you are clear with understanding of the function – no need to read further. If you got lost here is the same in simple words – it is lot like finding median with percentile value. Now let’s have fun following query: USE AdventureWorks GO SELECT SalesOrderID, OrderQty, ProductID, PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY ProductID) OVER (PARTITION BY SalesOrderID) AS MedianCont FROM Sales.SalesOrderDetail WHERE SalesOrderID IN (43670, 43669, 43667, 43663) ORDER BY SalesOrderID DESC GO The above query will give us the following result: You can see that I have used PERCENTILE_COUNT(0.5) in query, which is similar to finding median. Let me explain above diagram with little more explanation. The defination of median is as following: In case of Even Number of elements = In ordered list add the two digits from the middle and devide by 2 In case of Odd Numbers of elements = In ordered list select the digits from the middle I hope this example gives clear idea how PERCENTILE_CONT() works. Reference: Pinal Dave (http://blog.SQLAuthority.com) Filed under: Pinal Dave, PostADay, SQL, SQL Authority, SQL Function, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, T SQL, Technology

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• Use an audio/video file from a Linux laptop via USB to be played by Magic Sing ET-23H

  - by AisIceEyes

  I am one of the technical directors of a regular karaoke contest event. For the karaoke contest itself, due to tight budget, we are using what one of the sponsors are providing - Magic Sing ET-23H . The video output of the Magic Sing ET-23H are broadcasted at two big screens that are being shown to the audience and event attendees. When a karaoke contestant provides his / her karaoke video, the video itself is in a readable USB flashdrive and is attached to the USB input of Magic Sing ET-23H. What really bugs me is that the interface of Magic Sing ET-23H are also being broadcasted at the big screen video feeds. The interface of choosing the video file is being seen in the Magic Sing ET-23H - also to the big video screens that are seen by the audience and event goers. I will post in the comments ( if my less than 10 reputation would allow me) the picture of Magic Sing ET-23KH USB input of the device. I always bring my laptop, Acer AS5742-7653, during the regular karaoke event. I'm using my laptop also for tallying of scores from the judges, and also playing audio files from contestants that did not provide a karaoke video. I personally am using different Linux distros, but I next to all the time use my Ubuntu Studio 12.04.3 64bit partition during the regular karaoke contest event. My question is this: Is there a way I can share a temporary video/audio file directly from the laptop I'm using, going to the Magic Sing ET-23H that can broadcast both the video/audio file? Just like how in Window's Avisynth AVS files, or VirtualDub's temporary avi file, or like using ffplay (of ffmpeg), etc. I have researched somewhat the matter and found links in SuperUser.com. Though I can only provide the links at the comments section of this post if my reputation of less than 10 would allow me. I have a hunch it is possible, but I have not fully understood the device being used at the event, Magic Sing ET-23H, if there are other ways for it to broadcast video and audio files besides its USB input. Any help to my current predicament is highly appreciated. Thank you. PS: Since I need at least 10 reputation to post more than 2 links and also post images, I will try to post the image & links at the comments (if my below 10 reputation would allow me).

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• called function A(args) calls a function B() which then calls a function A(args), How to do that?

  - by Ken

  See example: <!DOCTYPE html> <html> <head> <title>language</title> <script type="text/javascript" src="http://www.google.com/jsapi"> </script> </head> <body> <div id="language"></div> <script type="text/javascript"> var loaded = false; function load_api() { google.load("language", "1", { "nocss": true, "callback": function() { loaded = true; callback_to_caller(with_caller_agruments); // how to call a function (with the same arguments) which called load_api() ??? // case 1 should be: detect_language('testing'); // case 2 should be: translate('some text'); } }); } function detect_language(text) { if (!loaded) { load_api(); } else { // let's continue... believe that google.language is loaded & ready to use google.language.detect(text, function(result) { if (!result.error && result.language) { document.getElementById('language').innerHTML = result.language; } }); } } function translate(text) { if (!loaded) { load_api(); } else { // let's continue... } } detect_language('testing'); // case 1 translate('some text'); // case 2 </script> </body> </html>

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• Visual Studio 2008 “Format Document/Selection” command and a function named “assert” in JavaScript c

  - by AGS777

  Just have found some funny behavior of the Visual Studio 2008 editor.  Sorry if it is already well known bug. If you happened to have a JavaScript function named “assert” in your code (and there is pretty high likelihood in my opinion), for example something like: function assert(x, message) { if (x) console.log(message); } then when either Format Document (Ctrl + K, Ctrl + D) or Format Selection (Ctrl + K, Ctrl + F) command is applied to the document/block containing the function, the result of the formatting will be: functionassert(x, message) { if (x) console.log(message); } That’s it. function and assert are now joined into one solid word. So be aware of the fact in case you suddenly start receiving  strange exception in your JavaScript code: missing ; before statement functionassert(x, message) And no, it is not an April Fool's joke. Just try for yourself.

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• printable PHP manual - 'all but the Function Reference section'

  - by JW01

  My Motivation I find it easier to learn things by reading 'offline'. I'd like to lean back and read the narrative part of a paper version of the official php manual. My Scuppered Plan My plan was to download the manual, print all but the Function Reference section and then read it. I have downloaded the "Single HTML file" version of the manual from the php.net download page. (That version did not contain any images, so I patched-in the ones from the Many HTML files version with no problem.) My plan was to open that "Single HTML file" in an HTML editor, delete the Function Reference section then print it out. Unfortunately, although I have tried three different editors, I have not been able to successfully load-up that massive html file to be able to edit it. Its about (~40MB). I started to look into the phpdoc framework with a view to rendering my own html docs from the source...but that's a steep learning curve for a newby..and is a last resort. I would use a file splitter, but they tend to split files crudely with no regard for html/xml/xhtml sematics. So the question is... Does anyone know know where you can download the php manual in a version that is a kind of half-way house between the 'Single HTML file' and the 'Many HTML files'? Ideally with the docs split into 3 parts: File 1 - stuff before the function reference File 2 - function reference File 3 - stuff after the function reference Or Can you suggest any editors/tools will enable me to split up this file myself?

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• Passing additional parameters to JQuery bind event function

  - by kazim sardar mehdi

  To pass the additional parameter to the event function pass an array of key value, as the second parameter to the bind event bind('click', { message: time }, onClick); e.g { message: time } and access it in the function using event(function parameter).data.message(key)   <div id="div1" style="border: 1px solid black; width: 100px; height: 100px">click me</div> <script type="text/javascript"> function onClick(event) { alert(event.data.message); } var time = "loaded at:" + new Date().toString(); $("div.#div1").bind('click', { message: time }, onClick); </script>

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• Ord function implementation in Delphi

  - by Federico Zancan

  Purely as an exercise at home, aimed to better understand some language basics, I tried to reimplement the Ord function, but I came across a problem. In fact, the existing Ord function can accept arguments of a variety of different types (AnsiChar, Char, WideChar, Enumeration, Integer, Int64) and can return Integer or Int64. I can't figure out how to declare multiple versions of the same function. How should this be coded in Delphi?

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• What happens at control invoke function?

  - by user65909

  A question about form controls invoke function. Control1 is created on thread1. If you want to update something in Control1 from thread2 you must do something like: delegate void SetTextCallback(string txt); void setText(string txt) { if (this.textBox1.InvokeRequired) { SetTextCallback d = new SetTextCallback(setText); this.Invoke(d, new object[] { txt }); } else { // this will run on thread1 even when called from thread2 this.textBox1.AppendText(msg); } }` What happens behind the scenes here? This invoke behaves different from a normal object invoke. When you want to call a function in an object on a specific thread, then that thread must be waiting on some queue of delegates, and execute the incoming delegates. Is it correct that the windows forms control invoke function is completely different from the standard object invoke function?

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• Anonymous function vs. separate named function for initialization in jquery

  - by Martin N.

  We just had some controversial discussion and I would like to see your opinions on the issue: Let's say we have some code that is used to initialize things when a page is loaded and it looks like this: function initStuff() { ...} ... $(document).ready(initStuff); The initStuff function is only called from the third line of the snippet. Never again. Now I would say: Usually people put this into an anonymous callback like that: $(document).ready(function() { //Body of initStuff }); because having the function in a dedicated location in the code is not really helping with readability, because with the call on ready() makes it obvious, that this code is initialization stuff. Would you agree or disagree with that decision? And why? Thank you very much for your opinion!

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• JS closures - Passing a function to a child, how should the shared object be accessed

  - by slicedtoad

  I have a design and am wondering what the appropriate way to access variables is. I'll demonstrate with this example since I can't seem to describe it better than the title. Term is an object representing a bunch of time data (a repeating duration of time defined by a bunch of attributes) Term has some print functionality but does not implement the print functions itself, rather they are passed in as anonymous functions by the parent. This would be similar to how shaders can be passed to a renderer rather than defined by the renderer. A container (let's call it Box) has a Schedule object that can understand and use Term objects. Box creates Term objects and passes them to Schedule as required. Box also defines the print functions stored in Term. A print function usually takes an argument and uses it to return a string based on that argument and Term's internal data. Sometime the print function could also use data stored in Schedule, though. I'm calling this data shared. So, the question is, what is the best way to access this shared data. I have a lot of options since JS has closures and I'm not familiar enough to know if I should be using them or avoiding them in this case. Options: Create a local "reference" (term used lightly) to the shared data (data is not a primitive) when defining the print function by accessing the shared data through Schedule from Box. Example: var schedule = function(){ var sched = Schedule(); var t1 = Term( function(x){ // Term.print() return (x + sched.data).format(); }); }; Bind it to Term explicitly. (Pass it in Term's constructor or something). Or bind it in Sched after Box passes it. And then access it as an attribute of Term. Pass it in at the same time x is passed to the print function, (from sched). This is the most familiar way for my but it doesn't feel right given JS's closure ability. Do something weird like bind some context and arguments to print. I'm hoping the correct answer isn't purely subjective. If it is, then I guess the answer is just "do whatever works". But I feel like there are some significant differences between the approaches that could have a large impact when stretched beyond my small example.

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• run .profile function as cron job

  - by Don

  In the .profile file of the root user I have defined a function, e.g. function printDate() { date } I want to run this function every minute and append the output to cron.log. I tried adding the following crontab entry: * * * * * printDate > $HOME/cron.log 2>&1 But it doesn't work. The cron.log file gets created, but it's empty. I guess this is because the .profile isn't read by cron, so any functions/aliases defined therein are unavailable to it. So I tried changing the crontab entry to: * * * * * source $HOME/.profile;printDate >> $HOME/cron.log 2>&1 But this doesn't work either. It seems cron still doesn't have access to the printDate function because I see the following in cron.log /bin/sh: printDate: not found

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• Best Method of function parameter validation

  - by Aglystas

  I've been dabbling with the idea of creating my own CMS for the experience and because it would be fun to run my website off my own code base. One of the decisions I keep coming back to is how best to validate incoming parameters for functions. This is mostly in reference to simple data types since object validation would be quite a bit more complex. At first I debated creating a naming convention that would contain information about what the parameters should be, (int, string, bool, etc) then I also figured I could create options to validate against. But then in every function I still need to run some sort of parameter validation that parses the parameter name to determine what the value can be then validate against it, granted this would be handled by passing the list of parameters to function but that still needs to happen and one of my goals is to remove the parameter validation from the function itself so that you can only have the actual function code that accomplishes the intended task without the additional code for validation. Is there any good way of handling this, or is it so low level that typically parameter validation is just done at the start of the function call anyway, so I should stick with doing that.

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