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  • C++ OOP: Which functions to put into the class?

    - by oh boy
    Assume I have a class a: class a { public: void load_data( ); private: void check_data( ); void work_data( ); void analyze_data( ); } Those functions all do something with the class or one of its members. However this function: bool validate_something( myType myData ) { if ( myData.blah > 0 && myData.blah < 100 ) { return true; } return false; } Is related to the class and will only be called by it, so it won't be needed anywhere else Doesn't do anything with the class or its members - just a small "utility" function Where to put validate_something? Inside or outside the class?

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  • JavaScript: One ID, two functions. How can I do this with minimal code duplication?

    - by user1775598
    I've got an ID and I'd like to assign two functions to it. Here's what it currently looks like: document.getElementById(this.config.dragArea).addEventListener("drop", this._dropFiles, false); document.getElementById(this.config.dragArea).addEventListener("drop", this._handleFileDrop, false); How can I rewrite this file without so much duplication? I tried doing document.getElementById(this.config.dragArea).addEventListener("drop", this._dropFiles, this._handleFileDrop, false); and document.getElementById(this.config.dragArea).addEventListener("drop", function(){this._dropFiles; this._handleFileDrop}, false); All to no avail :(

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  • Is there some file browser that uses low level functions to browse hard disk?

    - by watbywbarif
    I have Windows 7, NTFS hard disk. I have detected rootkit files but can't delete them through Windows explorer, obviously because they are not visible. Is there some other file browser that is using low level function calls, lower that win api, so that I can try to see and study these files before removal. I know the exact locations. I know that I can load some live CD and delete them, but I wonder about the first possible solution.

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  • 'hijacking' gui and mapping certain controls to certain functions. VNC. TouchOSC

    - by Nick
    I need a VNC LIKE application which rather than sharing the screen, can take control of a specific application and then share that functionality across a network to multiple clients. Obviously, VNC requires use of the mouse and therefore only one user can do something at one time, this is NOT what I am after. I am after something that can hijack the graphic user interface, map certain controls, and then display them in another piece of software (perhaps like TOUCHOSC) The software I would like to map and share is called YAMAHA STUDIO MANAGER and is used to control certain Yamaha audio hardware, and in my case a Yamaha LS9 and M7CL mixing console. Its free.

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  • How to visualize the design of a program in order to communicate it to others

    - by Joris Meys
    I am (re-)designing some packages for R, and I am currently working out the necessary functions, objects, both internal and for the interface with the user. I have documented the individual functions and objects. So I have the description of all the little parts. Now I need to give an overview of how the parts fit together. The scheme of the motor so to say. I've started with making some flowchart-like graphs in Visio, but that quickly became a clumsy and useless collection of boxes, arrrows and-what-not. So hence the question: Is there specific software you can use for vizualizing the design of your program If so, care to share some tips on how to do this most efficiently If not, how do other designers create the scheme of their programs and communicate that to others? Edit: I am NOT asking how to explain complex processes to somebody, nor asking how to illustrate programming logic. I am asking how to communicate the design of a program/package, i.e.: the objects (with key features and representation if possible) the related functions (with arguments and function if possible) the interrelation between the functions at the interface and the internal functions (I'm talking about an extension package for a scripting language, keep that in mind) So something like this : But better. This is (part of) the interrelations between functions in the old package that I'm now redesigning for obvious reasons :-) PS : I made that graph myself, using code extraction tools on the source and feeding the interrelation matrix to yEd Graph Editor.

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  • Effective handling of variables in non-object oriented programming

    - by srnka
    What is the best method to use and share variables between functions in non object-oriented program languages? Let's say that I use 10 parameters from DB, ID and 9 other values linked to it. I need to work with all 10 parameters in many functions. I can do it next ways: 1. call functions only with using ID and in every function get the other parameters from DB. Advantage: local variables are clear visible, there is only one input parameter to function Disadvantage: it's slow and there are the same rows for getting parameters in every function, which makes function longer and not so clear 2. call functions with all 10 parameters Advantage: working with local variables, clear function code Disadvantage: many input parameters, what is not nice 3. getting parameters as global variables once and using them everywhere Advantage - clearer code, shorter functions, faster processing Disadvantage - global variables - loosing control of them, possibility of unwanted overwriting (Especially when some functions should change their values) Maybe there is some another way how to implement this and make program cleaner and more effective. Can you say which way is the best for solving this issue?

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  • Chaining functions in jQuery. I cannot find an explanation anywhere.

    - by Marius
    Hello there, I have no idea how to do this. My markup: <table> <tr> <td id="colLeft"> Lorem ipsum dolor<br/> Lorem ipsum dolor<br/> Lorem ipsum dolor<br/> Lorem ipsum dolor<br/> Lorem ipsum dolor<br/> Lorem ipsum dolor. </td> <td id="colRight"> <div>1</div> <div>2</div> </td> </tr> </table> $(document).ready(function() { $('#colRight > div').each(function() { // I try to: select all divs in #colRight $(this).height(function(){ // I try to: sets the height of each div to: $('#colLeft').height() / $('#colRight > div').length(); // the height of #colLeft divided by the number of divs in colRight. }); }); }); What I am trying to do is to change the height of each div to the height of #colLeft divided by the number of divs in #colRight. However, it doesnt work. I've never understood how to chain functions, and never found anyone to teach me. So I would like to ask two favours of you. Why doesnt my above jQuery code. Does anyone know of a tutorial that explains it more detailed than in the tutorials on the jQuery website? Thank you for your time. Kind regards, Marius

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  • How can I use "Dependency Injection" in simple php functions, and should I bother?

    - by Tchalvak
    I hear people talking about dependency injection and the benefit of it all the time, but I don't really understand it. I'm wondering if it's a solution to the "I pass database connections as arguments all the time" problem. I tried reading wikipedia's entry on it, but the example is written in Java so I don't solidly understand the difference it is trying to make clear. ( http://en.wikipedia.org/wiki/Dependency_injection ). I read this dependency-injection-in-php article ( http://www.potstuck.com/2009/01/08/php-dependency-injection/ ), and it seems like the objective is to not pass dependencies to an object directly, but to cordon off the creation of an object along with the creation of it's dependencies. I'm not sure how to apply that in a using php functions context, though. Additionally, is the following Dependency Injection, and should I bother trying to do dependency injection in a functional context? Version 1: (the kind of code that I create, but don't like, every day) function get_data_from_database($database_connection){ $data = $database_connection->query('blah'); return $data; } Version 2: (don't have to pass a database connection, but perhaps not dependency injection?) function get_database_connection(){ static $db_connection; if($db_connection){ return $db_connection; } else { // create db_connection ... } } function get_data_from_database(){ $conn = get_database_connection(); $data = $conn->query('blah'); return $data; } $data = get_data_from_database(); Version 3: (the creation of the "object"/data is separate, and the database code is still, so perhaps this would count as dependency injection?) function factory_of_data_set(){ static $db_connection; $data_set = null; $db_connection = get_database_connection(); $data_set = $db_connection->query('blah'); return $data_set; } $data = factory_of_data_set(); Anyone have a good resource or just insight that makes the method and benefit -crystal- clear?

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  • Qt Socket blocking functions required to run in QThread where created. Any way past this?

    - by Alexander Kondratskiy
    The title is very cryptic, so here goes! I am writing a client that behaves in a very synchronous manner. Due to the design of the protocol and the server, everything has to happen sequentially (send request, wait for reply, service reply etc.), so I am using blocking sockets. Here is where Qt comes in. In my application I have a GUI thread, a command processing thread and a scripting engine thread. I create the QTcpSocket in the command processing thread, as part of my Client class. The Client class has various methods that boil down to writing to the socket, reading back a specific number of bytes, and returning a result. The problem comes when I try to directly call Client methods from the scripting engine thread. The Qt sockets randomly time out and when using a debug build of Qt, I get these warnings: QSocketNotifier: socket notifiers cannot be enabled from another thread QSocketNotifier: socket notifiers cannot be disabled from another thread Anytime I call these methods from the command processing thread (where Client was created), I do not get these problems. To simply phrase the situation: Calling blocking functions of QAbstractSocket, like waitForReadyRead(), from a thread other than the one where the socket was created (dynamically allocated), causes random behaviour and debug asserts/warnings. Anyone else experienced this? Ways around it? Thanks in advance.

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  • Can I combine two functions into one using Javascript?

    - by Melissa
    I have the following code that I would like to simplify. With javascript and jQuery is there an easy way that I could combine these two functions? Most of the code is the same but I am not sure how I could create a single function that works differently depending on what is clicked. $(document).ready(function () { $('#ListBooks').click(ListBooks); $('#Create').click(Create); }); function Create() { var dataSourceID = $('#DataSourceID').val(); var subjectID = $('#SubjectID').val(); var contentID = $('#ContentID').val(); if (dataSourceID && dataSourceID != '00' && subjectID && subjectID != "00" && contentID && contentID != "00") { var e = encodeURIComponent, arr = ["dataSourceID=" + e(dataSourceID), "subjectID=" + e(subjectID), "contentID=" + e(contentID)]; window.location.href = '/Administration/Books/Create?' + arr.join("&"); } else { alert('Datasource, Subject and Content must be selected.'); } return false; } function ListBooks() { var dataSourceID = $('#DataSourceID').val(); var subjectID = $('#SubjectID').val(); var contentID = $('#ContentID').val(); if (dataSourceID && dataSourceID != '00' && subjectID && subjectID != "00" && contentID && contentID != "00") { var e = encodeURIComponent, arr = ["dataSourceID=" + e(dataSourceID), "subjectID=" + e(subjectID), "contentID=" + e(contentID)]; window.location.href = '/Administration/Books/ListBooks?' + arr.join("&"); } else { alert('Datasource, Subject and Content must be selected.'); } return false; }

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  • What is the cleanest way to use anonymous functions?

    - by Fletcher Moore
    I've started to use Javascript a lot more, and as a result I am writing things complex enough that organization is becoming a concern. However, this question applies to any language that allows you to nest functions. Essentially, when should you use an anonymous function over a named global or inner function? At first I thought it was the coolest feature ever, but I think I am going overboard. Here's an example I wrote recently, ommiting all the variable delcarations and conditionals so that you can see the structure. function printStream() { return fold(function (elem, acc) { ... var comments = (function () { return fold(function (comment, out) { ... return out + ...; }, '', elem.comments); return acc + ... + comments; }, '', data.stream); } I realized though (I think) there's some kind of beauty in being so compact, it is probably isn't a good idea to do this in the same way you wouldn't want a ton of code in a double for loop.

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  • Refactoring code/consolidating functions (e.g. nested for-loop order)

    - by bmay2
    Just a little background: I'm making a program where a user inputs a skeleton text, two numbers (lower and upper limit), and a list of words. The outputs are a series of modifications on the skeleton text. Sample inputs: text = "Player # likes @." (replace # with inputted integers and @ with words in list) lower = 1 upper = 3 list = "apples, bananas, oranges" The user can choose to iterate over numbers first: Player 1 likes apples. Player 2 likes apples. Player 3 likes apples. Or words first: Player 1 likes apples. Player 1 likes bananas. Player 1 likes oranges. I chose to split these two methods of outputs by creating a different type of dictionary based on either number keys (integers inputted by the user) or word keys (from words in the inputted list) and then later iterating over the values in the dictionary. Here are the two types of dictionary creation: def numkey(dict): # {1: ['Player 1 likes apples', 'Player 1 likes...' ] } text, lower, upper, list = input_sort(dict) d = {} for num in range(lower,upper+1): l = [] for i in list: l.append(text.replace('#', str(num)).replace('@', i)) d[num] = l return d def wordkey(dict): # {'apples': ['Player 1 likes apples', 'Player 2 likes apples'..] } text, lower, upper, list = input_sort(dict) d = {} for i in list: l = [] for num in range(lower,upper+1): l.append(text.replace('#', str(num)).replace('@', i)) d[i] = l return d It's fine that I have two separate functions for creating different types of dictionaries but I see a lot of repetition between the two. Is there any way I could make one dictionary function and pass in different values to it that would change the order of the nested for loops to create the specific {key : value} pairs I'm looking for? I'm not sure how this would be done. Is there anything related to functional programming or other paradigms that might help with this? The question is a little abstract and more stylistic/design-oriented than anything.

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  • Are UTF16 (as used by for example wide-winapi functions) characters always 2 byte long?

    - by Cray
    Please clarify for me, how does UTF16 work? I am a little confused, considering these points: There is a static type in C++, WCHAR, which is 2 bytes long. (always 2 bytes long obvisouly) Most of msdn and some other documentation seem to have the assumptions that the characters are always 2 bytes long. This can just be my imagination, I can't come up with any particular examples, but it just seems that way. There are no "extra wide" functions or characters types widely used in C++ or windows, so I would assume that UTF16 is all that is ever needed. To my uncertain knowledge, unicode has a lot more characters than 65535, so they obvisouly don't have enough space in 2 bytes. UTF16 seems to be a bigger version of UTF8, and UTF8 characters can be of different lengths. So if a UTF16 character not always 2 bytes long, how long else could it be? 3 bytes? or only multiples of 2? And then for example if there is a winapi function that wants to know the size of a wide string in characters, and the string contains 2 characters which are each 4 bytes long, how is the size of that string in characters calculated? Is it 2 chars long or 4 chars long? (since it is 8 bytes long, and each WCHAR is 2 bytes)

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  • How do I make custom functions chain-able with jQuery's?

    - by sergio
    I need a "callfront" or "precall" (the opposite of "callback" ¿?) to add in MANY places before an animation occurs in an existing plugin, To be used like e.g. $(some_unpredictable_obj).preFunct().animate(… The problem is, as I said they are MANY places, and all of them are different animations, on different objects. I can TELL where all of them occur, but I don't want to add over and over the same code. I actually have to add both a function before and after those animations, but I think I can use the callback for all of them. In a perfect world, I'd like to replace every animate(property, duration) by preFunct().animate(property,duration).postFunct() preFunct and postFunct don't need parameters, since they are always the same action, on the same object. This could be an amazing addition to "jQuery" (an easy way to jQuerize custom functions to be added to the normal chain (without messing with queues) I found this example but it will act on the applied element, and I don't want that because, as I said above, all the original animations to be added to are on different elements. I also found jQuery.timing, but it looks cooler the chain-able function :) Thanks.

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  • Is There a Better Way to Feed Different Parameters into Functions with If-Statements?

    - by FlowofSoul
    I've been teaching myself Python for a little while now, and I've never programmed before. I just wrote a basic backup program that writes out the progress of each individual file while it is copying. I wrote a function that determines buffer size so that smaller files are copied with a smaller buffer, and bigger files are copied with a bigger buffer. The way I have the code set up now doesn't seem very efficient, as there is an if loop that then leads to another if loops, creating four options, and they all just call the same function with different parameters. import os import sys def smartcopy(filestocopy, dest_path, show_progress = False): """Determines what buffer size to use with copy() Setting show_progress to True calls back display_progress()""" #filestocopy is a list of dictionaries for the files needed to be copied #dictionaries are used as the fullpath, st_mtime, and size are needed if len(filestocopy.keys()) == 0: return None #Determines average file size for which buffer to use average_size = 0 for key in filestocopy.keys(): average_size += int(filestocopy[key]['size']) average_size = average_size/len(filestocopy.keys()) #Smaller buffer for smaller files if average_size < 1024*10000: #Buffer sizes determined by informal tests on my laptop if show_progress: for key in filestocopy.keys(): #dest_path+key is the destination path, as the key is the relative path #and the dest_path is the top level folder copy(filestocopy[key]['fullpath'], dest_path+key, callback = lambda pos, total: display_progress(pos, total, key)) else: for key in filestocopy.keys(): copy(filestocopy[key]['fullpath'], dest_path+key, callback = None) #Bigger buffer for bigger files else: if show_progress: for key in filestocopy.keys(): copy(filestocopy[key]['fullpath'], dest_path+key, 1024*2600, callback = lambda pos, total: display_progress(pos, total, key)) else: for key in filestocopy.keys(): copy(filestocopy[key]['fullpath'], dest_path+key, 1024*2600) def display_progress(pos, total, filename): percent = round(float(pos)/float(total)*100,2) if percent <= 100: sys.stdout.write(filename + ' - ' + str(percent)+'% \r') else: percent = 100 sys.stdout.write(filename + ' - Completed \n') Is there a better way to accomplish what I'm doing? Sorry if the code is commented poorly or hard to follow. I didn't want to ask someone to read through all 120 lines of my poorly written code, so I just isolated the two functions. Thanks for any help.

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  • Why do you need "extern C" for in C++ callbacks to C functions?

    - by Artyom
    Hello, I find such examples in Boost code. namespace boost { namespace { extern "C" void *thread_proxy(void *f) { .... } } // anonymous void thread::thread_start(...) { ... pthread_create(something,0,&thread_proxy,something_else); ... } } // boost Why do you actually need this extern "C"? It is clear that thread_proxy function is private internal and I do not expect that it would be mangled as "thread_proxy" because I actually do not need it mangled at all. In fact in all my code that I had written and that runs on may platforms I never used extern "C" and this had worked as-as with normal functions. Why extern "C" is added? My problem is that extern "C" function pollute global name-space and they do not actually hidden as author expects. This is not duplicate! I'm not talking about mangling and external linkage. It is obvious in this code that external linkage is unwanted!

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  • What is the best practice for including jQuery ext functions?

    - by Metropolis
    Hey everyone, Currently I have a file that I named JQuery.ext.js which I am including in all of my pages. Inside this file I have numerous functions that do things like the following, (function($) { /** * Checks to see is the value inside ele is blank * @param message string The message that needs to be displayed if the element is blank * @return bool */ $.fn.isEmpty = function(message) { var b_IsEmpty = false; //Loop through all elements this.each(function() { //Check to see if an empty value is found if($(this).val().length <= 0) { //If message is not blank if(message) { alert(message); $(this).focus().select(); } b_IsEmpty = true; return false; } return true; }); //Return false if the evaluation failed, otherwise return the jquery object so we can reuse it return (b_IsEmpty) ? true : false; }; /** * Checks to see if the value inside ele is numbers only * @param message string The message that needs to be displayed if the element is not numeric * @return bool */ $.fn.isNumeric = function(message) { var expression = /^[0-9]+$/; var b_IsNumeric = true; //Loop through elements checking each one this.each( function() { //Check to see if this value is not numeric if(!$(this).val().match(expression) && $(this).val().length > 0) { //If message is not blank if(message) { alert(message); $(this).focus().select(); } b_IsNumeric = false; } return b_IsNumeric; }); return b_IsNumeric; }; })(jQuery); Is there another way to do this? or is this the way most people do it? Thanks for any help, Metropolis

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  • Can you dynamically combine multiple conditional functions into one in Python?

    - by erich
    I'm curious if it's possible to take several conditional functions and create one function that checks them all (e.g. the way a generator takes a procedure for iterating through a series and creates an iterator). The basic usage case would be when you have a large number of conditional parameters (e.g. "max_a", "min_a", "max_b", "min_b", etc.), many of which could be blank. They would all be passed to this "function creating" function, which would then return one function that checked them all. Below is an example of a naive way of doing what I'm asking: def combining_function(max_a, min_a, max_b, min_b, ...): f_array = [] if max_a is not None: f_array.append( lambda x: x.a < max_a ) if min_a is not None: f_array.append( lambda x: x.a > min_a ) ... return lambda x: all( [ f(x) for f in f_array ] ) What I'm wondering is what is the most efficient to achieve what's being done above? It seems like executing a function call for every function in f_array would create a decent amount of overhead, but perhaps I'm engaging in premature/unnecessary optimization. Regardless, I'd be interested to see if anyone else has come across usage cases like this and how they proceeded. Also, if this isn't possible in Python, is it possible in other (perhaps more functional) languages?

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  • What new Unicode functions are there in C++0x?

    - by luiscubal
    It has been mentioned in several sources that C++0x will include better language-level support for Unicode(including types and literals). If the language is going to add these new features, it's only natural to assume that the standard library will as well. However, I am currently unable to find any references to the new standard library. I expected to find out the answer for these answers: Does the new library provide standard methods to convert UTF-8 to UTF-16, etc.? Does the new library allowing writing UTF-8 to files, to the console (or from files, from the console). If so, can we use cout or will we need something else? Does the new library include "basic" functionality such as: discovering the byte count and length of a UTF-8 string, converting to upper-case/lower-case(does this consider the influence of locales?) Finally, are any of these functions are available in any popular compilers such as GCC or Visual Studio? I have tried to look for information, but I can't seem to find anything? I am actually starting to think that maybe these things aren't even decided yet(I am aware that C++0x is a work in progress).

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  • template specialization for static member functions; howto?

    - by Rolle
    I am trying to implement a template function with handles void differently using template specialization. The following code gives me an "Explicit specialization in non-namespace scope" in gcc: template <typename T> static T safeGuiCall(boost::function<T ()> _f) { if (_f.empty()) throw GuiException("Function pointer empty"); { ThreadGuard g; T ret = _f(); return ret; } } // template specialization for functions wit no return value template <> static void safeGuiCall<void>(boost::function<void ()> _f) { if (_f.empty()) throw GuiException("Function pointer empty"); { ThreadGuard g; _f(); } } I have tried moving it out of the class (the class is not templated) and into the namespace but then I get the error "Explicit specialization cannot have a storage class". I have read many discussions about this, but people don't seem to agree how to specialize function templates. Any ideas?

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  • C++ -- Why should we use operator -> to access member functions of a SmartPtr?

    - by q0987
    Hello all, The question is given in the last two lines of code. template<class T> // template class for smart class SmartPtr { // pointers-to-T objects public: SmartPtr(T* realPtr = 0); T* operator->() const; T& operator*() const; T* Detach( void ) { T* pData = pointee; pointee = NULL; return pData; } private: T *pointee; ... }; class TestClass {} SmartPtr<TestClass> sPtr(new TestClass); TestClass* ptrA = sPtr->Detach(); // why I always see people use this method to access member functions of a Smart pointer. We can use sPtr-> b/c we have defined operator->() in SmartPtr. TestClass* ptrB = sPtr.Detach(); // Question: Is this a valid C++ way? If not, why? Thank you

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  • In Lua, can I easily select the Nth result without custom functions?

    - by romkyns
    Suppose I am inserting a string into a table as follows: table.insert(tbl, mystring) and that mystring is generated by replacing all occurrences of "a" with "b" in input: mystring = string.gsub(input, "a", "b") The obvious way to combine the two into one statement doesn't work, because gsub returns two results: table.insert(tbl, string.gsub(input, "a", "b")) -- error! -- (second result of gsub is passed into table.insert) which, I suppose, is the price paid for supporting multiple return values. The question is, is there a standard, built-in way to select just the first return value? When I found select I thought that was exactly what it did, but alas, it actually selects all results from N onwards, and so doesn't help in this scenario. Now I know I can define my own select as follows: function select1(n, ...) return arg[n] end table.insert(tbl, select1(1, string.gsub(input, "a", "b"))) but this doesn't look right, since I'd expect a built-in way of doing this. So, am I missing some built-in construct? If not, do Lua developers tend to use a separate variable to extract the correct argument or write their own select1 functions?

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  • Deprecated functions not spotted if using "System::Threading::ThreadState" (and others!) C++ VS2005/

    - by Fishboy
    Hi, I'm facing an issue with c++ on vs2005 and also vs2008... here's how you can reproduce the issue.... create a new (c++) project called 'test' (file|new|project) select "Windows Forms Application" and add the 'stdio.h' include and the code fragment below into the test.cpp source file..... -------------------start of snippet-------------------- #include <stdio.h> ... int main(array<System::String ^> ^args) { int i; System::Threading::ThreadState state; char str[20]; sprintf (str, "%s", "test string"); ... -------------------end of snippet-------------------- If you compile the code as above (you'll have to 'buildall' first), you'll get two warnings about 'i' and 'state' being unreferenced (nothing about sprintf being deprecated). If you comment out "System::Threading :Thread state;", you'll get one warning about 'i' being unreferenced and another warning (C4996) for the 'deprecated' sprintf statement.... This issue also occurs for "System::Windows::Forms::MessageBoxIcon", "System::Base64FormattingOptions" (and perhap all 'enum class' types!) Anyone know of the cause and workaround to the issue demonstrated here ( i have other files that demonstate this issue..). (I had started a thread on msdn, but then found this site! see link below) Visual Studio 2005 has stopped warning about deprecated functions

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  • How do you get and set a class property across multiple functions in Objective-C?

    - by editor
    Following up on this question about sharing objects between classes, I now need to figure out how to share the objects across various functions in a class. First, the setup: In my App Delegate I load menu information from JSON into a NSMutableDictionary and message that through to a view controller using a function called initWithData. I need to use this dictionary to populate a new Table View, which has methods like numberOfRowsInSection and cellForRowAtIndexPath. I'd like to use the dictionary count to return numberOfRowsInSection and info in the dictionary to populate each cell. Unfortunately, my code never gets beyond the init stage and the dictionary is empty so numberOfRowsInSection always returns zero. I thought I could create a class property, synthesize it and then set it. But it doesn't seem to want to retain the property's value. What am I doing wrong here? In the header .h: @interface FirstViewController:UIViewController <UITableViewDataSource, UITableViewDelegate, UITabBarControllerDelegate> { NSMutableDictionary *sectorDictionary; NSInteger sectorCount; } @property (nonatomic, retain) NSMutableDictionary *sectorDictionary; - (id)initWithData:(NSMutableDictionary*)data; @end in the implementation .m: - (id) testFunction:(NSMutableDictionary*)dictionary { NSLog(@"Count #1: %d", [dictionary count]); return nil; } - (id)initWithData:(NSMutableDictionary *)data { if (!(self=[super init])) { return nil; } [self testFunction:data]; // this is where I'd like to set a retained property self.sectorDictionary = data; return nil; } - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section { NSLog(@"Count #2: %d", [self.sectorDictionary count]); return [self.sectorDictionary count]; } Output from NSLog: 2010-05-04 23:00:06.255 JSONApp[15890:207] Count #1: 9 2010-05-04 23:00:06.259 JSONApp[15890:207] Count #2: 0

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  • Patterns to deal with with functions that can have different kinds of results.

    - by KaptajnKold
    Suppose you have an method on an object that given the some input alters the objects state if the input validates according to some complex logic. Now suppose that when the input doesn't validate, it can be due to several different things, each of which we would like to be able to deal with in different ways. I'm sure many of you are thinking: That's what exceptions are for! I've thought of this also. But my reservation against using exceptions is that in some cases there is nothing exceptional about the input not validating and I really would like to avoid using exceptions to control what is really just in the expected flow of the program. If there were only one interpretation possible, I could simply choose to return a boolean value indicating whether or not the operation resulted in a state change or not and the respond appropriately when it did not. There is of course also the option to return a status code which the client can then choose to interpret or not. I don't like this much either because there is nothing semantic about status codes. The solution I have so far is to always check for each possible situation which I am able to handle before I call the method which then returns a boolean to inform the client if the object changed state. This leaves me the flexibility to handle as few or as many as the possible situations as I wish depending on the context I am in. It also has the benefit of making the method I am calling simpler to write. The drawback is that there is quite a lot of duplication in the client code wherever I call the method. Which of these solutions do you prefer and why? What other patterns do people use for providing meaningful feedback from functions? I know that some languages support multiple return values, and I if I had that option I would surely prefer it.

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