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  • how to callback a lua function from a c function

    - by pierr
    Hi, I have a c function test_callback accepting a point to a function as the parameter and It will "callback" that function. //typedef int(*data_callback_t)(int i); int test_callback(data_callback_t f) { f(3); } int datacallback(int a ) { printf("called back %d\n",a); return 0; } //example test_callback(datacallback); // print : called back 3 Now, I want to wrap test_callback so that they can be called from lua, suppose the name is lua_test_callback ;and also the input parameter to it would be a lua function. How should I achieve this goal? function lua_datacallback (a ) print "hey , this is callback in lua" ..a end lua_test_callback(lua_datacallback) //expect to get "hey this is callback in lua 3 "

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  • What are function pointers good for ?

    - by gramm
    Hi, I have trouble seing the utility of the function pointers. I guess it may be useful in some case (it exists, after all), but I can't think of a case where it's better or unavoidable to use a function pointer. Could you give some example of good use of function pointers (in C or C++)? Many thanks :)

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  • I need help understanding how this jQuery filter function works, line-by-line, if possible

    - by user717236
    Here is the HTML: <div> <h3>text</h3> </div> <div> <h3>moretext</h3> </div> <div> <h3>123</h3> </div>?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? Here is the JS: var rv1_wlength = $("div").filter(function() { return $(this).find("h3").filter(function () { return $(this).text() != "123"; }).length; }); var rv1_wolength = $("div").filter(function() { return $(this).find("h3").filter(function () { return $(this).text() != "123"; }); }); var rv2 = $("div").find("h3").filter(function() { return $(this).text() != "123"; }); alert(rv1_wlength.text()); // text // moretext alert(rv1_wolength.text()); // text // moretext // 123 alert(rv2.text());? // textmoretext I don't understand why the first two methods print the elements on each line, whereas the second method concatenates them. "rv2" is a jQuery object. Then, what are the first two (rv1_wlength and rv1_wolength)? Furthermore, I don't understand why the inclusion of the length property makes all the difference in filtering the elements. The second method does nothing, since it returns all the elements. The first method, with the only change being the addition of the length property, correctly filters the elements. I would very much like a line-by-line explanation. I would sincerely appreciate any feedback. Thank you.

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  • Creating/populating Javascript custom object

    - by Ek0nomik
    I've created an ashx page which is going to serve me an XML document full of basic user information. I'm not sure which is the best way to go about creating and populating my custom javascript object. I've seen them created in two ways: function User() { this.Id; this.FirstName; this.LastName; this.Title; } and var User2 = { Id: null, FirstName: null, LastName: null, Title: null } I could populate each of these by doing something like: //first object User.Id = 1 //second object User2.FirstName = 'John' Is one method of creating the object better than the other?

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  • What question(s) does an object's behavior answer?

    - by Corwin
    Reading a book I have found the following statement: (Object) Behaviors answer either of two questions: What does this object do (for me)? or What can I do to this object? In the case of an orange, it doesn’t do a whole lot, but we can do things to it. One behavior is that it can be eaten. In my understanding of object behaviour the statement above is correct regarding the first question and is incorrect in case of the second. However, I often see classes with methods like Orange::eat(), and this makes me uncertain about my design skills. So I would like to ask is it a design mistake to give oranges a behaviour eat? (oranges and eat are used just for example)

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  • Call to a member function get_segment() error

    - by hogofwar
    I'm having this problem with this piece of PHP code: class Core { public function start() { require("funk/funks/libraries/uri.php"); $this->uri = new uri(); require("funk/core/loader.php"); $this->load = new loader(); if($this->uri->get_segment(1) != "" and file_exists("funk/pages/".$uri->get_segment(1).".php")){ Only a snippet of the code The best way I can explain it is that it is a class calling upon another class (uri.php) and i am getting the error: Fatal error: Call to a member function get_segment() on a non-object in /home/eeeee/public_html/private/funkyphp/funk/core/core.php on line 11 (the if($this-uri-get_segment(1) part) I'm having this problem a lot and it is really bugging me. the library code is: <?php class uri { private $server_path_info = ''; private $segment = array(); private $segments = 0; public function __construct() { $segment_temp = array(); $this->server_path_info = preg_replace("/\?/", "", $_SERVER["PATH_INFO"]); $segment_temp = explode("/", $this->server_path_info); foreach ($segment_temp as $key => $seg) { if (!preg_match("/([a-zA-Z0-9\.\_\-]+)/", $seg) || empty($seg)) unset($segment_temp[$key]); } foreach ($segment_temp as $k => $value) { $this->segment[] = $value; } unset($segment_temp); $this->segments = count($this->segment); } public function segment_exists($id = 0) { $id = (int)$id; if (isset($this->segment[$id])) return true; else return false; } public function get_segment($id = 0) { $id--; $id = (int)$id; if ($this->segment_exists($id) === true) return $this->segment[$id]; else return false; } } ?>

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  • pointer to const member function typedef

    - by oldcig
    I know it's possible to separate to create a pointer to member function like this struct K { void func() {} }; typedef void FuncType(); typedef FuncType K::* MemFuncType; MemFuncType pF = &K::func; Is there similar way to construct a pointer to a const function? I've tried adding const in various places with no success. I've played around with gcc some and if you do template deduction on something like template <typename Sig, typename Klass> void deduce(Sig Klass::*); It will show Sig with as a function signature with const just tacked on the end. If to do this in code it will complain that you can't have qualifiers on a function type. Seems like it should be possible somehow because the deduction works.

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  • Looking for early paper about compiling object-oriented code

    - by Robert Kosara
    I remember reading a paper a long time ago that talked about object-oriented programming. I believe that this was from the early 1980s or perhaps even before then. This was at the time when object-oriented programming was still done through pre-processors, and one thing that stuck with me is this: it argued that you could write code in either procedural or object-oriented fashion, and after preprocessing/compiling, you would end up with the exact same machine code. Does anybody know which paper I'm talking about?

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  • removing dependancy of a private function inside a public function using Rhino Mocks

    - by L G
    Hi All, I am new to mocking, and have started with Rhino Mocks. My scenario is like this..in my class library i have a public function and inside it i have a private function call, which gets output from a service.I want to remove the private function dependency. public class Employee { public virtual string GetFullName(string firstName, string lastName) { string middleName = GetMiddleName(); return string.Format("{0} {2} {1}", firstName, lastName,middleName ); } private virtual string GetMiddleName() { // Some call to Service return "George"; } } This is not my real scenario though, i just wanted to know how to remove dependency of GetMiddleName() function and i need to return some default value while unit testing. Note : I won't be able to change the private function here..or include Interface..Keeping the functions as such, is there any way to mock this.Thank

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  • Passing a pointer to a function that doesn't match the requirements of the formal parameter

    - by Andreas Grech
    int valid (int x, int y) { return x + y; } int invalid (int x) { return x; } int func (int *f (int, int), int x, int y) { //f is a pointer to a function taking 2 ints and returning an int return f(x, y); } int main () { int val = func(valid, 1, 2), inval = func(invalid, 1, 2); // <- 'invalid' does not match the contract printf("Valid: %d\n", val); printf("Invalid: %d\n", inval); /* Output: * Valid: 3 * Invalid: 1 */ } At the line inval = func(invalid, 1, 2);, why am I not getting a compiler error? If func expects a pointer to a function taking 2 ints and I pass a pointer to a function that takes a single int, why isn't the compiler complaining? Also, since this is happening, what happens to the second parameter y in the invalid function?

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  • Giving my function access to outside variable

    - by brett
    I have an array outside: $myArr = array(); I would like to give my function access to the array outside it so it can add values to it function someFuntion(){ $myVal = //some processing here to determine value of $myVal $myArr[] = $myVal; } How do I give the function the right scoping to the variable?

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  • Jquery Var Returned As object

    - by alex
    I'm trying to pass a variable from one function to another, but the var elmId is being returned as an object and giving an error. When we click on any of the generated divs we should be able to change the size of the div by choosing a width / height value from the drop down menus. I'm trying to pass the clicked div id which is elmId to function displayVals but it is not working. If we replace "#"+elmId in the function displayVals with the actual id of the first div created with is "#divid1" then it works. Why is the value of var elmId not being passed to displayVals <link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.7/themes/base/jquery-ui.css" type="text/css" media="all" /> <script src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.4/jquery.min.js" type="text/javascript"></script> <script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.7/jquery-ui.min.js" type="text/javascript"></script> <style> .aaa{width:100px; height:100px; background-color:#ccc;} button{width:100px; height:20px;} </style> <button class="idiv">div</button> <select id="width"> <option>100px</option> <option>200px</option> <option>300px</option> </select> <select id="height"> <option>100px</option> <option>200px</option> <option>300px</option> </select> <p></p> <script type="text/javascript"> var divId = 1; $("button").click(function(){ var elm = $('<div id=divid' + divId + ' class=aaa></div>'); elm.appendTo('p'); divId++; }); $("p").click(function(e){ var elmType = $(e.target)[0].nodeName, elmId = $(e.target)[0].id; return displayVals(elmId); }); function displayVals(elmId) { var iwidth = $("#width").val(); var iheight = $("#height").val(); $("#"+elmId).css({width:iwidth, height:iheight}); console.log(elmId); } $("select").change(displayVals); displayVals(); </script>

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  • Function name inside a variable

    - by John Doe
    Hello. I have a simple question (i guess). I'm getting the name of the function inside a variable from database. After that, i want to run the specific function. How can i echo the function's name inside the php file? The code is something like this: $variable= get_specific_option; //execute function $variable_somesuffix(); The "somesuffix" will be a simple text. I tried all the things i had in mind but nothing worked.

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  • How to catch unintentional function interpositioning?

    - by SiegeX
    Reading through my book Expert C Programming, I came across the chapter on function interpositioning and how it can lead to some serious hard to find bugs if done unintentionally. The example given in the book is the following: my_source.c mktemp() { ... } main() { mktemp(); getwd(); } libc mktemp(){ ... } getwd(){ ...; mktemp(); ... } According to the book, what happens in main() is that mktemp() (a standard C library function) is interposed by the implementation in my_source.c. Although having main() call my implementation of mktemp() is intended behavior, having getwd() (another C library function) also call my implementation of mktemp() is not. Apparently, this example was a real life bug that existed in SunOS 4.0.3's version of lpr. The book goes on to explain the fix was to add the keyword static to the definition of mktemp() in my_source.c; although changing the name altogether should have fixed this problem as well. This chapter leaves me with some unresolved questions that I hope you guys could answer: Does GCC have a way to warn about function interposition? We certainly don't ever intend on this happening and I'd like to know about it if it does. Should our software group adopt the practice of putting the keyword static in front of all functions that we don't want to be exposed? Can interposition happen with functions introduced by static libraries? Thanks for the help. EDIT I should note that my question is not just aimed at interposing over standard C library functions, but also functions contained in other libraries, perhaps 3rd party, perhaps ones created in-house. Essentially, I want to catch any instance of interpositioning regardless of where the interposed function resides.

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  • calling function in radiobutton group

    - by vijisai
    thank you very much. with your help, i am now able to call the function for each radio button. however, i get a error message Reference to non-existent field 'ics_si' ics_si is my function, which has the following code, i do not know where i am making a mistake i have created the edit box for user to input the values for bore and stroke. and vdisp is calculated and the result is displayed in the third edit box. function ics_si_Callback(hObject, eventdata, handles) b = str2double(get(handles.bore,'String')); s = str2double(get(handles.stroke,'String')); vdisp = (pi * b * b * s*10^(-3))/4; set(handles.vdisp,'String',vdisp); this code must be called when i press the first or second radio button. i.e. when the radio button is pressed, it should call the function ics_si, calculate it and display the result. how to get this.

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  • How to pass function reference into arguments

    - by Ockonal
    Hi, I'm using boost::function for making function-references: typedef boost::function<void (SomeClass &handle)> Ref; someFunc(Ref &pointer) {/*...*/} void Foo(SomeClass &handle) {/*...*/} What is the best way to pass Foo into the someFunc? I tried something like: someFunc(Ref(Foo));

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  • How to store a function in a member of class? (Using function as callback)

    - by Dane
    I want to store a function as a class member and call it inside the class? Pretty much like a callback function. My class draw a document but every document must drawn differently. So I want to assign a function (written outside of the class) into one of the members of the class and then call it when I want to draw the document. This function mostly is responsible for transforming objects according to each specific document. Here is my class: class CDocument { public: CDocument(); ~CDocument(); void *TransFunc(); } void Transform() { } int main() CDocument* Doc = new CDocument(); Doc->TransFunc = Transform(); } I know that this is probably simple question, but I couldn't find the answer by googling or searching SO.

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  • PHP5: restrict access to function to certain classes

    - by Tim
    Is there a way in PHP5 to only allow a certain class or set of classes to call a particular function? For example, let's say I have three classes ("Foo", "Bar", and "Baz"), all with similarly-named methods, and I want Bar to be able to call Foo::foo() but deny Baz the ability to make that call: class Foo { static function foo() { print "foo"; } } class Bar { static function bar() { Foo::foo(); print "bar"; } // Should work } class Baz { static function baz() { Foo::foo; print "baz"; } // Should fail } Foo::foo(); // Should also fail There's not necessarily inheritance between Foo, Bar, and Baz, so the use of protected or similar modifiers won't help; however, the methods aren't necessarily static (I made them so here for the simplicity of the example).

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  • Pass variable name to a function in r

    - by Misha
    Is it possible to pass just a variable name in a function call and have it utilised as such within the function?? pseudocode: q<-function(A){ b<-(w%in%A.2|w%in%A.7) factor(b,levels=c(F,T),labels=c("non-"A,A))} w<-c(0:10) e.2<-c(1,2) e.7<-c(6,7) what I´d like to do is q(e) and have returned non-e,e,e,non-e,non-e,e,e,non-e,non-e //M q<-function(A) { a2<-get(paste(a,".2",sep="")) a7<-get(paste(a,".7",sep="")) b<-(w%in%a2|%in%a7) factor(b,levels=c(F,T),labels=c(paste("non-",a,sep=""),a)) } q("e") Thx, M

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  • Constructing a function call in C

    - by 0x6adb015
    Given that I have a pointer to a function (provided by dlsym() for example) and a linked list of typed arguments, how can I construct a C function call with those arguments? Example: struct param { enum type { INT32, INT64, STRING, BOOL } type; union { int i32; long long i64; char *str; bool b; } value; struct param *next; }; int call_this(int (*function)(), struct param *args) { int result; /* magic here that calls function(), which has a prototype of f(int, long long, char *, bool); , when args consist of a linked list of INT32, INT64, STRING, BOOL types. */ return result; } The OS is Linux. I would like the solution to be portable across MIPS, PPC and x86 (all 32 bits) architecture, using GCC as the compiler. Thanks!

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