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  • Callback from static library

    - by MortenHN
    I think this should be simple, but im having a real hard time finding information about this topic. I have made a static library and have no problem getting the basics to work. But im having a hard time figuring out how to make a call back from the static library to the main APP. I would like my static library to only use one header as front, this header should contain functions like: requestImage:(NSString *)path; requestLikstOfSomething:(NSSting *)guid; and so on.. These functions should do the necessary work and start a async NSURLConnection, and call back to the main application when the call have finished. How do you guys do this, what are the best ways to callback from a static library when a async method is finished? should i do this with delegates (is this possible), notifications, key/value observers. I really want to know how you guys have solved this, and what you regard as the best practices. Im going to have 20-25 different calls so i want the static library header file to be as simple as possible preferable only with a list of the 20-25 functions. UPDATE: My question is not how to use delegate pattern, but witch way is the best to do callbacks from static librarys. I would like to use delegates but i dont want to have 20-25 protocol declarations in the public header file. I would prefer to have only one function for each request. Thanks in advance. Best regards Morten

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  • Haskell function composition (.) and function application ($) idioms: correct use.

    - by Robert Massaioli
    I have been reading Real World Haskell and I am nearing the end but a matter of style has been niggling at me to do with the (.) and ($) operators. When you write a function that is a composition of other functions you write it like: f = g . h But when you apply something to the end of those functions I write it like this: k = a $ b $ c $ value But the book would write it like this: k = a . b . c $ value Now to me they look functionally equivalent, they do the exact same thing in my eyes. However, the more I look, the more I see people writing their functions in the manner that the book does: compose with (.) first and then only at the end use ($) to append a value to evaluate the lot (nobody does it with many dollar compositions). Is there a reason for using the books way that is much better than using all ($) symbols? Or is there some best practice here that I am not getting? Or is it superfluous and I shouldn't be worrying about it at all? Thanks.

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  • WHY JSLint complains: "someFunction() was used before it was defined"?

    - by 7hi4g0
    Searching for the JSLint error "was used before it was defined" i've found these: JSLint: Using a function before it's defined error Function was used before it was defined - JSLint JSLint: was used before it was defined jsLint error: “somefunction() was used before it was defined” jslint - Should we tolerate misordered definitions? Problem None of those answers WHY the error is shown. Elaboration According to the ECMA-262 Specification functions are evaluated before execution starts, hence all functions declared using the function keyword are available to all the code idenpendent of the place they were declared (assuming they are acessible on that scope). This is otherwise known as hoisting. Douglas Crockford seems to think it is better to declare every function before the code that uses it regardless of the hoisting effect. According to StackOverflowNewbie in his question, this raises some code organization problems. Not to mention some people, like me, prefer to declare their functions underneath the main/init code. On those questions there are some ways to avoid or fix the error, such as using function expressions vs function declarations. But none of them showed me the reason of the error. Not even Crockford's site. Question(s) Why is it an error to call a function before the declaration, even if it was declared using the function keyword? Is it better to use function expressions instead of function declaration in the JSLint context? If one is preferred, why? Note Not looking for answers like: Crockford is a tyrant Is just Crockford's opinion Thank you :*

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  • Programmatically parse and edit C++ Source Files

    - by Kryten
    Hi, I want to able programmatically parse and edit C++ source files. I need to be able to change/add code in certain sections of code (i.e. in functions, class blocks, etc). I would also (preferably) be able to get comments as well. Part of what I want to do can be explained by the following piece of code: CPlusPlusSourceParser cp = new CPlusPlusSourceParser(“x.cpp”); // Create C++ Source Parser Object CPlusPlusSourceFunction[] funcs = cp.getFunctions(); // Get all the functions for (int i = 0; i &lt funcs.length; i++) { // Loop through all functions funcs[i].append(/* … code I want to append …*/); // Append some code to function } cp.save(); // Save new source cp.close(); // Close file How can I do that? I’d like to be able to do this preferably in Java, C++, Perl, Python or C#. However, I am open to other language API’s.

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  • Javascript (using jQuery) in a large Project... organization, passing data, private method, etc.

    - by gaoshan88
    I'm working on a large project that is organized like so: Multiple javascript files are included as needed and most code is wrapped in anonymous functions... // wutang.js //Included Files Go Here // Public stuff var MethodMan; // Private stuff (function() { var someVar1; MethodMan = function(){...}; var APrivateMethod = function(){...}; $(function(){ //jquery page load stuff here $('#meh').click(APrivateMethod); }); })(); I'm wondering about a few things here. Assuming that there are a number of these files included on a page, what has access to what and what is the best way to pass data between the files? For example, I assume that MethodMan() can be accessed by anything on any included page. It is public, yes? var someVar1 is only accessible to the methods inside that particular anonymous function and nowhere else, yes? Also true of var APrivateMethod(), yes? What if I want APrivateMethod() to make something available to some other method in a different anonymous wrapped method in a different included page. What's the best way to pass data between these private, anonymous functions on different included pages? Do I simply have to make whatever I want to use between them public? How about if I want to minimize global variables? What about the following: var PootyTang = function(){ someVar1 = $('#someid').text(); //some stuff }; and in another included file used by that same page I have: var TangyPoot = function(){ someVar1 = $('#someid').text(); //some completely different stuff }; What's the best way to share the value of someVar1 across these anonymous (they are wrapped as the first example) functions?

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  • How to compensate the flipped coordinate system of core graphics for easy drawing?

    - by mystify
    It's really a pain, but always when I draw an UIImage in -drawRect:, it's upside-down. When I flip the coordinates, the image draws correctly, but at the cost of all other CG functions drawing "wrong" (flipped). What's your strategy when you have to draw images and other things? Is there any rule of thumb how to not get stuck in this problem over and over again? Also, one nasty thing when I flip the y-axis is, that my CGRect from the UIImageView frame is wrong. Instead of the origin appearing at 10,10 upper left as expected, it appears at the bottom. But at the same time, all those normal line drawing functions of CGContext take correct coordinates. drawing a line in -drawRect with origin 10,10 upper left, will really start at upper left. But at the same time that's strange, because core graphics actually has a flipped coordinate system with y 0 at the bottom. So it seems like something is really inconsistent there. Drawing with CGContext functions takes coordinates as "expected" (cmon, nobody thinks in coordinates starting from bottom left, that's silly), while drawing any kind of image still works the "wrong" way. Do you use helper methods to draw images? Or is there anything useful that makes image drawing not a pain in the butt?

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  • Iphone -- maintaining a list of strings and a corresponding typedef enum

    - by William Jockusch
    Suppose I have the following: typedef enum functionType {ln, sin, sqrt} functionType; NSArray *functions = [NSArray arrayWithObjects: @"ln", @"sin", @"sqrt", nil]; Suppose further that *functions will not change at runtime. Question -- is there any way to set up a single structure which updates both of these? So that I only have to keep track of one list, instead of two. To explain what is going on -- the idea is that string input from the user will be stored in a variable of type functionType. Later on, I will have code like this: double valueOfFunction: (functionType) function withInput: (double) input switch (function) { case ln: return ln(input); case sin: return sin(input); case sqrt: return sqrt(input); //etc . . . could grow to include a lot of functions. } And valueOfFunction needs to be fast. So I don't want to be doing string comparisons there.

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  • Using C struct without including header file

    - by shams
    My basic problem is that I want to use some structs and functions defined in a header file by not including that header file in my code. The header file is generated by a tool. Since I don't have access to the header file, I can't include it in my program. Here's a simple example of my scenario: first.h #ifndef FIRST_H_GUARD #define FIRST_H_GUARD typedef struct ComplexS { float real; float imag; } Complex; Complex add(Complex a, Complex b); // Other structs and functions #endif first.c #include "first.h" Complex add(Complex a, Complex b) { Complex res; res.real = a.real + b.real; res.imag = a.imag + b.imag; return res; } my_program.c // I cannot/do not want to include the first.h header file here // but I want to use the structs and functions from the first.h #include <stdio.h> int main() { Complex a; a.real = 3; a.imag = 4; Complex b; b.real = 6; b.imag = 2; Complex c = add(a, b); printf("Result (%4.2f, %4.2f)\n", c.real, c.imag); return 0; } My intention is to build an executable for my_program and then use the linker to link up the executables. Is what I want to achieve possible in C?

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  • What is the fastest (possibly unsafe) way to read a byte[]?

    - by Aidiakapi
    I'm working on a server project in C#, and after a TCP message is received, it is parsed, and stored in a byte[] of exact size. (Not a buffer of fixed length, but a byte[] of an absolute length in which all data is stored.) Now for reading this byte[] I'll be creating some wrapper functions (also for compatibility), these are the signatures of all functions I need: public byte ReadByte(); public sbyte ReadSByte(); public short ReadShort(); public ushort ReadUShort(); public int ReadInt(); public uint ReadUInt(); public float ReadFloat(); public double ReadDouble(); public string ReadChars(int length); public string ReadString(); The string is a \0 terminated string, and is probably encoded in ASCII or UTF-8, but I cannot tell that for sure, since I'm not writing the client. The data exists of: byte[] _data; int _offset; Now I can write all those functions manually, like this: public byte ReadByte() { return _data[_offset++]; } public sbyte ReadSByte() { byte r = _data[_offset++]; if (r >= 128) return (sbyte)(r - 256); else return (sbyte)r; } public short ReadShort() { byte b1 = _data[_offset++]; byte b2 = _data[_offset++]; if (b1 >= 128) return (short)(b1 * 256 + b2 - 65536); else return (short)(b1 * 256 + b2); } public short ReadUShort() { byte b1 = _data[_offset++]; return (short)(b1 * 256 + _data[_offset++]); } But I wonder if there's a faster way, not excluding the use of unsafe code, since this seems a little bit too much work for simple processing.

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  • Need advice on C++ coding pattern

    - by Kotti
    Hi! I have a working prototype of a game engine and right now I'm doing some refactoring. What I'm asking for is your opinion on usage of the following C++ coding patterns. I have implemented some trivial algorithms for collision detection and they are implemented the following way: Not shown here - class constructor is made private and using algorithms looks like Algorithm::HandleInnerCollision(...) struct Algorithm { // Private routines static bool is_inside(Point& p, Object& object) { // (...) } public: /** * Handle collision where the moving object should be always * located inside the static object * * @param MovingObject & mobject * @param const StaticObject & sobject * @return void * @see */ static void HandleInnerCollision(MovingObject& mobject, const StaticObject& sobject) { // (...) } So, my question is - somebody advised me to do it "the C++" way - so that all functions are wrapped in a namespace, but not in a class. Is there some good way to preserve privating if I will wrap them into a namespace as adviced? What I want to have is a simple interface and ability to call functions as Algorithm::HandleInnerCollision(...) while not polluting the namespace with other functions such as is_inside(...) Of, if you can advise any alternative design pattern for such kind of logics, I would really appreciate that...

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  • How do I change the viewport of a window in win32?

    - by Colen
    Hi, I have a window with child windows inside in it. The child windows take up about 1000 pixels of vertical space. However, our users don't always have 1000 pixels of vertical space available - they might have as little as 500 or 600 pixels. I want to be able to display this window at a size of 500 pixels high, and have the user "scroll" up and down the window to see the full contents. The window should always be 500 pixels high, but the view within it should change. Assume I can add a scroll bar somewhere so the user can choose which part of the window he wants to see. Windows will normally paint the window contents from height 0 to height 500; how do I tell it instead to "paint from height 250 to height 750", for example? I know that I can set the viewport with functions like SetViewportOrgEx etc, but those functions require a device context - when do I call them if I want them to be "permanent"? Do I call them when I get the WM_PAINT message from windows? Or at some other time? And which functions from that family do I want to use? Thanks.

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  • own drawImage / drawLine in OpenGL

    - by Chrise
    I'm implementing some native 2D-draw functions in my graphics engine for android, but now there's another question coming up, when I observe the performance of my program. At the moment I'm implementing a drawLine/drawImage function. In summary, there are following different values for drawing each different line / image: the color the alpha value the width of the line rotation (only for images) size/scale (also for images) blending method (subrtract, add, normal-alpha) Now, when an imageLine is drawn, I put the CPU-calculated vertex-positions and uv-values for 6 vertices (2 triangles), into a Floatbuffer and draw it immediately with drawArrays, after passing information for drawing (color,alpha, etc.) via uniforms to the shader. When I draw an image, the pre-set VBO is directly drawn after passing information. The first fact I recognized, is: of course drawing Images is much faster, than imagelines (beacuse of VBOs), but also: I cannot pre-put vertex-data into a VBO for imageLines, because imageLines have no static shape like normal images (varying linelength, varying linewidth and the vertex positions of x1,y1 and x2,y2 change too often) That's why I use a normal Floatbuffer, instead of a VBO. So my question is: What's the best way for managing images, and other 2D-graphics functions. For me it's some kind of important, that the user of the engine is able to draw as many images/2D graphics as possible, without loosing to much performance. You can find the functions for drawing images, imagelines, rects, quads, etc. here: https://github.com/Chrise55/LLama3D/blob/master/Llama3DLibrary/src/com/llama3d/object/graphics/image/ImageBase.java Here an example how it looks with many images (testing artificial neural networks), it works fine, but already little bit slow with that many images... :(

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  • How to keep track of call statistics? C++

    - by tf.rz
    I'm working on a project that delivers statistics to the user. I created a class called Dog, And it has several functions. Speak, woof, run, fetch, etc. I want to have a function that spits out how many times each function has been called. I'm also interested in the constructor calls and destructor calls as well. I have a header file which defines all the functions, then a separate .cc file that implements them. My question is, is there a way to keep track of how many times each function is called? I have a function called print that will fetch the "statistics" and then output them to standard output. I was considering using static integers as part of the class itself, declaring several integers to keep track of those things. I know the compiler will create a copy of the integer and initialize it to a minimum value, and then I'll increment the integers in the .cc functions. I also thought about having static integers as a global variable in the .cc. Which way is easier? Or is there a better way to do this? Any help is greatly appreciated!

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  • Line by Line explanation of "Javascript: Good Parts" example?

    - by Matrym
    I'm reading "Javascript: The Good Parts" and am totally baffled by what's really going on here. A more detailed and/or simplified explanation would be greatly appreciated. // BAD EXAMPLE // Make a function that assigns event handler functions to an array of nodes the wrong way. // When you click on a node, an alert box is supposed to display the ordinal of the node. // But it always displays the number of nodes instead. var add_the_handlers = function (nodes) { var i; for (i = 0; i < nodes.length; i += 1) { nodes[i].onclick = function (e) { alert(i); } } }; // END BAD EXAMPLE The add_the_handlers function was intended to give each handler a unique number (i). It fails because the handler functions are bound to the variable i, not the value of the variable i at the time the function was made: // BETTER EXAMPLE // Make a function that assigns event handler functions to an array of nodes the right way. // When you click on a node, an alert box will display the ordinal of the node. var add_the_handlers = function (nodes) { var i; for (i = 0; i < nodes.length; i += 1) { nodes[i].onclick = function (i) { return function (e) { alert(i); }; }(i); } }; Now, instead of assigning a function to onclick, we define a function and immediately invoke it, passing in i. That function will return an event handler function that is bound to the value of i that was passed in, not to the i defined in add_the_handlers. That returned function is assigned to onclick.

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  • How do I launch a winforms form from a DLL correctly?

    - by rodent31337
    There's another question similar to mine, but I wanted to gather some specifics: I want to create a DLL that is called from unmanaged code. When the unmanaged functions are called in the DLL, I want to collect information and show it in a kind of form. What I'd like to do is, when DllMain() is called, and the reason is DLL_PROCESS_ATTACH, I would like to instantiate a form. This form should be run on a separate thread. When my function FOO() inside my DLL is called, I would like to take the information from FOO(), dispatch it to the form for rendering. So, more specifically: i) What is the proper way to create a DLL project and have the ability to have Windows forms created in the designer be available to the DLL? ii) What is the correct way to give this form its own thread and message processing loop? iii) How do I dispatch information from the unmanaged DLL functions to the form, or, alternatively a managed class that can update its own state and the form? The form inside the DLL is sort of a "monitor" for data passing in and out of the DLL, so I can keep track of errors/bugs, but not change the core functionality of the DLL functions that are available.

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  • creating an object within a function of a program

    - by user1066524
    could someone please tell me what I need to do in order to create an object in a function. I will try to explain by making up some sort of example... Let's say I have a program named TimeScheduler.cpp that implements the class Schedule.h (and I have the implementation in a separate file Schedule.cpp where we define the methods). In the declaration file we have declared two constructors Schedule(); //the default and Schedule(int, int, int);//accepts three arguments to get to the point--let's say in the main program file TimeScheduler.cpp we created our own functions in this program apart from the functions inherited from the class Schedule. so we have our prototypes listed at the top. /*prototypes*/ void makeSomeTime(); etc..... we have main(){ //etc etc... } we then define these program functions void makeSomeTime(){ //process } let's say that inside the function makeSomeTime(), we would like to create an array of Schedule objects like this Schedule ob[]={ summer(5,14, 49), fall(9,25,50) }; what do I have to do to the function makeSomeTime() in order for it to allow me to create this array of objects. The reason I ask is currently i'm having difficulty with my own program in that it WILL allow me to create this array of objects in main()....but NOT in a function like I just gave an example of. The strange thing is it will allow me to create a dynamic array of objects in the function..... like Schedule *ob = new Schedule[n+1]; ob[2]= Schedule(x,y,z); Why would it let me assign to a non-dynamic array in main(), but not let me do that in the function?

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  • C++: how to build my own utility library?

    - by augustin
    I am starting to be proficient enough with C++ so that I can write my own C++ based scripts (to replace bash and PHP scripts I used to write before). I find that I am starting to have a very small collection of utility functions and sub-routines that I'd like to use in several, otherwise unrelated C++ scripts. I know I am not supposed to reinvent the wheel and that I could use external libraries for some of the utilities I'm creating for myself. However, it's fun to create my own utility functions, they are perfectly tailored to the job I have in mind, and it's for me a large part of the learning process. I'll see about using more polished external libraries when I am proficient enough to work on more serious, long term projects. So, the question is: how do I manage my personal utility library in a way that the functions can be easily included in my various scripts? I am using linux/Kubuntu, vim, g++, etc. and mostly coding CLI scripts. Don't assume too much in terms of experience! ;) Links to tutorials or places where relevant topics are properly documented are welcome.

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  • possible to make codeigniter work with another framework?

    - by ajsie
    the situation is this. my client (who also is a programmer) asks me to develop an address book (with mysql database) with a lot of functions. then he can interact with some class methods i provide for him. kinda like an API. the situation is that the address book application is getting bigger and bigger, and i feel like its way better to use CodeIgniter to code it with MVC. i wonder if i can use codeigniter, then in some way give him the access to controller methods. eg. in a controller there are some functions u can call with the web browser. public function create_contact($information) {..} public function delete_contact($id) {..} public function get_contact($id) {..} however, these are just callable from web browser. how can i let my client have access to these functions like an API? then in his own application he can use: $result = $address_book-create_contact($information); if($result) { echo "Success"; } $contact = $address_book-get_contact($id); is this possible? cause i just know how to access the controller methods with the webbrowser. and i guess its not an option for him to use header(location) to access them. all suggestions to make this possible are welcomed! thanks

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  • jQuery Mobile: How to run a callback-function before $.mobile.changePage?

    - by Jugi84
    I'm setting up a mobile app with jQuery Mobile and PhoneGap. What I want to do is that when I click link with id "news_link" I want jQuery to fetch data from database and put it to jQm's collapsible set. In my solution, I've wanted to use $.mobile.changePage inside callback functions because I want to wait until the data has been fetched and put inside the container before the code changes page. Here's the code: $(function() { $('#news_link').click(function(){ loadNewsFromDB(function(){ $.mobile.changePage( $("#news"), { transition: "slideup"} ); }); }); loadNewsFromDB is PhoneGap's SQLite database function which would fetch the data with more callback functions from database. The contents would be put to desired container with .html-function function loadNewsFromDB(){ //some code here theDB.transaction(function(tx) { tx.executeSql(sqlStr, [], onLoadNewsSuccess, onLoadNewsError); },onTxError, onTxSuccess); function onLoadNewsSuccess(tx, results){ //some code here $("#newsSet").html(htmlCodeAndContentToPut); Html is jQm's basic ui-modules: <!-- some html code here --!> <div data-role="page" id="news"> <div data-role="content"> <div id="newsSet" data-role="collapsible-set" data-mini="true"> With debugging I know that the code work up until it works very well unti it arrives to $.mobile.changePage-function. Somehow it doesn't change the page. I've checked the function it works well in other occasions, but not inside callback-functions. I would be very grateful if someone would give me a hand am I not seeing something obviously wrong or is something more specific? What other workarounds there is for fetching the data from SQLite, waiting for data to be fetched, putting the data to container and then changing the pages?

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  • Storing C++ templated objects as same type

    - by JaredC
    I have a class that is a core component of a performance sensitive code path, so I am trying to optimize it as much as possible. The class used to be: class Widget { Widget(int n) : N(n) {} .... member functions that use the constant value N .... const int N; // just initialized, will never change } The arguments to the constructor are known at compile time, so I have changed this class to a template, so that N can be compiled into the functions: template<int N> class Widget { .... member functions that use N .... } I have another class with a method: Widget & GetWidget(int index); However, after templating Widget, each widget has a different type so I cannot define the function like this anymore. I considered different inheritance options, but I'm not sure that the performance gain from the template would outweigh the cost of inherited function invocations. SO, my question is this: I am pretty sure I want the best of both worlds (compile-time / run-time), and it may not be possible. But, is there a way to gain the performance of knowing N at compile time, but still being able to return Widgets as the same type? Thanks!

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  • Why onCreate() calling multiple times when i use Thread()?

    - by RajaReddy PolamReddy
    In my app i faced a problem with threads. i am using native code in my app. i try to load library and then calling native functions from the android code. 1. By using Threads() : PjsuaThread pjsuaThread = new PjsuaThread(); pjsuaThread.start(); thread code class PjsuaThread extends Thread { public void run() { if (pjsua_app.initApp() != 0) { // native function calling return; } else { } pjsua_app.startPjsua(ApjsuaActivity.CFG_FNAME); // native function calling finished = true; } When i use code like this, onCreate() function calling multiple times and able to load library and calling some functions properly, after some seconds onCreate calling again because of that it's crashing. 2. Using AsyncTask(): And also i used AsyncTask< for this requirement, it's crashing the application( crashing in lib code ). not able to open any functions class SipTask extends AsyncTask<Void, String, Void> { protected Void doInBackground(Void... args) { if (pjsua_app.initApp() != 0) { return null; } else { } pjsua_app.startPjsua(ApjsuaActivity.CFG_FNAME); finished = true; return null; } @Override protected void onPostExecute(Void result) { super.onPostExecute(result); Log.i(TAG, "On POst "); } } What is annoying is that in most cases it is not the missing library, it's tried to able to load the lib crashing in between. any one know the reason ?

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  • C Map String to Function

    - by Scriptonaut
    So, I'm making a Unix minishell, and have come to a roadblock. I need to be able to execute built-in functions, so I made a function: int exec_if_built_in(char **args) It takes an array of strings(the first being the command, and the rest being arguments). For non built-in commands I simply use something like execvp, however I need to find a way to map the first string to a function. I was thinking of making two arrays, one of strings, and another with their corresponding function pointers. However, since many of these functions will be different(return and accept different things), this approach won't work. I also thought of making an array of structs with a name property and a function pointer property, however once again due to the varied nature of the functions I'll be using, this won't work. So, what's the best way to execute a function based on the input of a string? How do I map a string to a certain function? I'm not very familiar with function pointers so I may be missing something. Thank you guys for the help :)

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  • Why won't my code segfault on Windows 7?

    - by Trevor
    This is an unusual question to ask but here goes: In my code, I accidentally dereference NULL somewhere. But instead of the application crashing with a segfault, it seems to stop execution of the current function and just return control back to the UI. This makes debugging difficult because I would normally like to be alerted to the crash so I can attach a debugger. What could be causing this? Specifically, my code is an ODBC Driver (ie. a DLL). My test application is ODBC Test (odbct32w.exe) which allows me to explicitly call the ODBC API functions in my DLL. When I call one of the functions which has a known segfault, instead of crashing the application, ODBC Test simply returns control to the UI without printing the result of the function call. I can then call any function in my driver again. I do know that technically the application calls the ODBC driver manager which loads and calls the functions in my driver. But that is beside the point as my segfault (or whatever is happening) causes the driver manager function to not return either (as evidenced by the application not printing a result). One of my co-workers with a similar machine experiences this same problem while another does not but we have not been able to determine any specific differences.

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  • Is it possible in SQLAlchemy to filter by a database function or stored procedure?

    - by Rico Suave
    We're using SQLalchemy in a project with a legacy database. The database has functions/stored procedures. In the past we used raw SQL and we could use these functions as filters in our queries. I would like to do the same for SQLAlchemy queries if possible. I have read about the @hybrid_property, but some of these functions need one or more parameters, for example; I have a User model that has a JOIN to a bunch of historical records. These historical records for this user, have a date and a debit and credit field, so we can look up the balance of a user at a specific point in time, by doing a SUM(credit) - SUM(debit) up until the given date. We have a database function for that called dbo.Balance(user_id, date_time). I can use this to check the balance of a user at a given point in time. I would like to use this as a criterium in a query, to select only users that have a negative balance at a specific date/time. selection = users.filter(coalesce(Users.status, 0) == 1, coalesce(Users.no_reminders, 0) == 0, dbo.pplBalance(Users.user_id, datetime.datetime.now()) < -0.01).all() This is of course a non-working example, just for you to get the gist of what I'd like to do. The solution looks to be to use hybrd properties, but as I mentioned above, these only work without parameters (as they are properties, not methods). Any suggestions on how to implement something like this (if it's even possible) are welcome. Thanks,

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  • Mock implementations in C++

    - by forneo
    Hi guys, I need a mock implementation of a class - for testing purposes - and I'm wondering how I should best go about doing that. I can think of two general ways: Create an interface that contains all public functions of the class as pure virtual functions, then create a mock class by deriving from it. Mark all functions (well, at least all that are to be mocked) as virtual. I'm used to doing it the first way in Java, and it's quite common too (probably since they have a dedicated interface type). But I've hardly ever seen such interface-heavy designs in C++, thus I'm wondering. The second way will probably work, but I can't help but think of it as kind of ugly. Is anybody doing that? If I follow the first way, I need some naming assistance. I have an audio system that is responsible for loading sound files and playing the loaded tracks. I'm using OpenAL for that, thus I've called the interface "Audio" and the implementation "OpenALAudio". However, this implies that all OpenAL-specific code has to go into that class, which feels kind of limiting. An alternative would be to leave the class' name "Audio" and find a different one for the interface, e.g. "AudioInterface" or "IAudio". Which would you suggest, and why?

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