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  • Overload and hide methods in Java

    - by Marco
    Hi, i have an abstract class BaseClass with a public insert() method: public abstract class BaseClass { public void insert(Object object) { // Do something } } which is extended by many other classes. For some of those classes, however, the insert() method must have additional parameters, so that they instead of overriding it I overload the method of the base class with the parameters required, for example: public class SampleClass extends BaseClass { public void insert(Object object, Long param){ // Do Something } } Now, if i instantiate the SampleClass class, i have two insert() methods: SampleClass sampleClass = new SampleClass(); sampleClass.insert(Object object); sampleClass.insert(Object object, Long param); what i'd like to do is to hide the insert() method defined in the base class, so that just the overload would be visible: SampleClass sampleClass = new SampleClass(); sampleClass.insert(Object object, Long param); Could this be done in OOP?

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  • Calling a Sub or Function contained in a module using "CallByName" in VB/VBA

    - by Kratz
    It is easy to call a function inside a classModule using CallByName How about functions inside standard module? 'inside class module 'classModule name: clsExample Function classFunc1() MsgBox "I'm class module 1" End Function ' 'inside standard module 'Module name: module1 Function Func1() MsgBox "I'm standard module 1" End Function ' ' The main sub Sub Main() ' to call function inside class module dim clsObj as New clsExample Call CallByName(clsObj,"ClassFunc1") ' here's the question... how to call a function inside a standard module ' how to declare the object "stdObj" in reference to module1? Call CallByName(stdObj,"Func1") ' is this correct? End Sub

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  • Is it possible to implement events in C++?

    - by acidzombie24
    I wanted to implement a C# event in C++ just to see if i could do it. I got stuck, i know the bottom is wrong but what i realize my biggest problem is... How do i overload the () operator to be whatever is in T in this case int func(float)? I cant? can i? Can i implement a good alternative? #include <deque> using namespace std; typedef int(*MyFunc)(float); template<class T> class MyEvent { deque<T> ls; public: MyEvent& operator +=(T t) { ls.push_back(t); return *this; } }; static int test(float f){return (int)f; } int main(){ MyEvent<MyFunc> e; e += test; }

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  • delegating into private parts

    - by FredOverflow
    Sometimes, C++'s notion of privacy just baffles me :-) class Foo { struct Bar; Bar* p; public: Bar* operator->() const { return p; } }; struct Foo::Bar { void baz() { std::cout << "inside baz\n"; } }; int main() { Foo::Bar b; // error: 'struct Foo::Bar' is private within this context Foo f; f->baz(); // fine } Since Foo::Bar is private, I cannot declare b in main. Yet I can call methods from Foo::Bar just fine. Why the hell is this allowed? Was that an accident or by design?

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  • C++ operator[] syntax.

    - by Lanissum
    Just a quick syntax question. I'm writing a map class (for school). If I define the following operator overload: template<typename Key, typename Val> class Map {... Val* operator[](Key k); What happens when a user writes: Map<int,int> myMap; map[10] = 3; Doing something like that will only overwrite a temporary copy of the [null] pointer at Key k. Is it even possible to do: map[10] = 3; printf("%i\n", map[10]); with the same operator overload?

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  • Dynamic access to tables from another database inside an user function

    - by Alberto Martinez
    I have an user defined table function in SQL Server that aggregate data from several tables including a couple of tables of another database. That is done hardcoding the name of the database in the queries, but we want to make the database name configurable (because our databases usually share the server with the databases of other applications). I tried to construct a dynamic query string inside the function using the database name that is stored in a configuration table, but: When I tried exec(@sqlStatement) SQL Server said that execute string is not allowed inside a function. Then I tried exec sp_executesql @sqlStatement and the function was created, but when you execute it SQL Server says that inside a function you can only run extended functions and procedures. So the question is: is possible create a function or stored procedure that access a table in another database without having to recreate the function when the database name is different? TIA.

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  • Jquery mobile function calls before Ajax Request end

    - by rpmlins
    Here is my problem. When My Home page shows, I call the LoadUser functions, which on success, sets the globalUser variable with the returned json, and after it loads I call the alert function but it says globalUser is undefined. I have tried many other work arounds, but I always get the undefined mesage. If I call the alert(globalUser); on the success function, it works as expected alerting the object. $('#Home').live('pageshow', function(event) { $.when(LoadUser()).done(function(a1) { alert(globalUser); }); }); function LoadUser() { $.ajax({ // connects with the web service and validate de user input url: "http://localhost:51396/Icademy.asmx/GetUser", contentType: "application/json; charset=utf-8", data: { "userName": "'rodrigo'" }, dataType: "jsonp", success: function(json) { globalUser = JSON.parse(json.d); return globalUser; }, error: function(ret) { alert("Um erro ocorreu, tente novamente mais tarde."); } }); }

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  • overload == (and != , of course) operator, can I bypass == to determine whether the object is null

    - by LLS
    Hello, when I try to overload operator == and != in C#, and override Equal as recommended, I found I have no way to distinguish a normal object and null. For example, I defined a class Complex. public static bool operator ==(Complex lhs, Complex rhs) { return lhs.Equals(rhs); } public static bool operator !=(Complex lhs, Complex rhs) { return !lhs.Equals(rhs); } public override bool Equals(object obj) { if (obj is Complex) { return (((Complex)obj).Real == this.Real && ((Complex)obj).Imaginary == this.Imaginary); } else { return false; } } But when I want to use if (temp == null) When temp is really null, some exception happens. And I can't use == to determine whether the lhs is null, which will cause infinite loop. What should I do in this situation. One way I can think of is to us some thing like Class.Equal(object, object) (if it exists) to bypass the == when I do the check. What is the normal way to solve the problem?

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  • how to call operator () in c++

    - by anish
    in c++ i have following code class Foobar{ public: Foobar * operator()(){ return new Foobar; } My quesion is how to call the (); if i do Foobar foo() the constructor gets called i am confused about behaviour of () can some explain me

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  • Firefox running infinitely even after condition met in jquery function

    - by Kyle
    The following function is called with setTimeout(function () { get_progress(fileID,fileName)},8000); upon a form submit. The purpose of the function is to get read_file.php to read a txt file that stores the file upload status from a form (in percentage). Upon reaching 80%, my Firefox seems to run infinitely even when HEAD returns an error. Am I have too many recursions or have I used a wrong condition that's causing get_progress to run repeatedly even when filename does not exist in the folder ? function get_progress( fileID, filename) { $.ajax({ url: filename, type: 'HEAD', success: function() { $.ajax({ type: 'POST', url: 'read_file.php', data: 'filename=' +filename, success: function(html) { document.getElementById(fileID).innerHTML = html + ' <img src="images/loading.gif" />' setInterval(function() {get_progress(fileID,filename)},4000); } }); } });}

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  • Is it possible to supply template parameters when calling operator()?

    - by Paul
    I'd like to use a template operator() but am not sure if it's possible. Here is a simple test case that won't compile. Is there something wrong with my syntax, or is this simply not possible? struct A { template<typename T> void f() { } template<typename T> void operator()() { } }; int main() { A a; a.f<int>(); // This compiles. a.operator()<int>(); // This compiles. a<int>(); // This won't compile. return 0; }

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  • lua function as argument in C

    - by Nil
    I'm going to pass a function to another function which should operate with the passed function. For example: handler(fun1("foo",2)) handler(fun2(1e-10)) The handler is something like calling the passed function many times. I'm going to bind handler, fun1, fun2 to C-functions. fun1 and fun2 are going to return some user data with a pointer to some cpp-class so that I can further recover which function was it. The problem now is that fun1 and fun2 are going to be called before passed to handler. But I don't need this, what I need is the kind of function and its parameters. However, I should be able to call fun1 and fun2 alone without handler: fun1("bar",3) fun2(1e-5) Is it possible to get the context the function is called from? While typing the question, I realized I could do following handler(fun1, "foo",2); handler(fun2, 1e-10);

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  • Java: If I overwrite the .equals method, can I still test for reference equality with ==?

    - by shots fired
    I have the following situation: I need to sort trees based by height, so I made the Tree's comparable using the height attribute. However, I was also told to overwrite the equals and hashCode methods to avoid unpredictable behaviour. Still, sometimes I may want to compare the references of the roots or something along those lines using ==. Is that still possible or does the == comparison call the equals method?

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  • Returning a struct from a class method

    - by tree
    I have a header file that looks something like the following: class Model { private: struct coord { int x; int y; } xy; public: .... coord get() const { return xy; } }; And in yet another file (assume ModelObject exists): struct c { int x; int y; void operator = (c &rhs) { x = rhs.x; y = rhs.y; }; } xy; xy = ModelObject->get(); The compiler throws an error that says there is no known covnersion from coord to c. I believe it is because it doesn't know about coord type because it is declared inside of a class header. I can get around that by declaring the struct outside of the class, but I was wondering if it is possible to do the way I am, or is this generally considered bad practice

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  • How to include worksheet 3 and 4 in a cell formula provided?

    - by user21255
    I have been kindly given this formula with an explanation on how it works: Insert this formula into the cell B4 of the sheet "Cases": =IF(NOT(ISBLANK('1st'!B25)),'1st'!B25,IF(NOT(ISBLANK(INDIRECT("'2nd'!R" & (ROW($B4)-(COUNTA('1st'!$B:$B)-COUNTA('1st'!$B$1:$B$24))-4+25) & "C" & COLUMN(B4),FALSE))),INDIRECT("'2nd'!R" & (ROW($B4)-(COUNTA('1st'!$B:$B)-COUNTA('1st'!$B$1:$B$24))-4+25) & "C" & COLUMN(B4),FALSE),"")) Copy the formula to the other cells in the worksheet; the relative addresses will adjust automatically. The formula works like this: Check if there is content in 1st. If yes, copy it. If no, find out how many entries there are in 1st in total. (This is done by using the COUNTA function on the whole B column in 1st and subtracting the number of non-empty cells above the actual case data.) Use this information together with the current cells's number to find out the location of the cell that has to be copied from 2nd. Create the address of the cell and use the ISBLANK function on the INDIRECT function with that address to check if the cell is empty. If it is not, use the INDIRECT function again to display it. If it is empty, just display an empty string. Now this works fine when I have only 2 sheets. But lets say I want to include a third and fourth sheet (name as 3rd and 4th respectively), then what and should I put the formula for this in the formula above? There are actually 31 sheets but if I know how to add 3rd and 4th sheet in the formula, then I can figure out how to do the rest. Thanks

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  • JavaScript Class Patterns

    - by Liam McLennan
    To write object-oriented programs we need objects, and likely lots of them. JavaScript makes it easy to create objects: var liam = { name: "Liam", age: Number.MAX_VALUE }; But JavaScript does not provide an easy way to create similar objects. Most object-oriented languages include the idea of a class, which is a template for creating objects of the same type. From one class many similar objects can be instantiated. Many patterns have been proposed to address the absence of a class concept in JavaScript. This post will compare and contrast the most significant of them. Simple Constructor Functions Classes may be missing but JavaScript does support special constructor functions. By prefixing a call to a constructor function with the ‘new’ keyword we can tell the JavaScript runtime that we want the function to behave like a constructor and instantiate a new object containing the members defined by that function. Within a constructor function the ‘this’ keyword references the new object being created -  so a basic constructor function might be: function Person(name, age) { this.name = name; this.age = age; this.toString = function() { return this.name + " is " + age + " years old."; }; } var john = new Person("John Galt", 50); console.log(john.toString()); Note that by convention the name of a constructor function is always written in Pascal Case (the first letter of each word is capital). This is to distinguish between constructor functions and other functions. It is important that constructor functions be called with the ‘new’ keyword and that not constructor functions are not. There are two problems with the pattern constructor function pattern shown above: It makes inheritance difficult The toString() function is redefined for each new object created by the Person constructor. This is sub-optimal because the function should be shared between all of the instances of the Person type. Constructor Functions with a Prototype JavaScript functions have a special property called prototype. When an object is created by calling a JavaScript constructor all of the properties of the constructor’s prototype become available to the new object. In this way many Person objects can be created that can access the same prototype. An improved version of the above example can be written: function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { toString: function() { return this.name + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); In this version a single instance of the toString() function will now be shared between all Person objects. Private Members The short version is: there aren’t any. If a variable is defined, with the var keyword, within the constructor function then its scope is that function. Other functions defined within the constructor function will be able to access the private variable, but anything defined outside the constructor (such as functions on the prototype property) won’t have access to the private variable. Any variables defined on the constructor are automatically public. Some people solve this problem by prefixing properties with an underscore and then not calling those properties by convention. function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { _getName: function() { return this.name; }, toString: function() { return this._getName() + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); Note that the _getName() function is only private by convention – it is in fact a public function. Functional Object Construction Because of the weirdness involved in using constructor functions some JavaScript developers prefer to eschew them completely. They theorize that it is better to work with JavaScript’s functional nature than to try and force it to behave like a traditional class-oriented language. When using the functional approach objects are created by returning them from a factory function. An excellent side effect of this pattern is that variables defined with the factory function are accessible to the new object (due to closure) but are inaccessible from anywhere else. The Person example implemented using the functional object construction pattern is: var personFactory = function(name, age) { var privateVar = 7; return { toString: function() { return name + " is " + age * privateVar / privateVar + " years old."; } }; }; var john2 = personFactory("John Lennon", 40); console.log(john2.toString()); Note that the ‘new’ keyword is not used for this pattern, and that the toString() function has access to the name, age and privateVar variables because of closure. This pattern can be extended to provide inheritance and, unlike the constructor function pattern, it supports private variables. However, when working with JavaScript code bases you will find that the constructor function is more common – probably because it is a better approximation of mainstream class oriented languages like C# and Java. Inheritance Both of the above patterns can support inheritance but for now, favour composition over inheritance. Summary When JavaScript code exceeds simple browser automation object orientation can provide a powerful paradigm for controlling complexity. Both of the patterns presented in this article work – the choice is a matter of style. Only one question still remains; who is John Galt?

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  • JavaScript Class Patterns

    - by Liam McLennan
    To write object-oriented programs we need objects, and likely lots of them. JavaScript makes it easy to create objects: var liam = { name: "Liam", age: Number.MAX_VALUE }; But JavaScript does not provide an easy way to create similar objects. Most object-oriented languages include the idea of a class, which is a template for creating objects of the same type. From one class many similar objects can be instantiated. Many patterns have been proposed to address the absence of a class concept in JavaScript. This post will compare and contrast the most significant of them. Simple Constructor Functions Classes may be missing but JavaScript does support special constructor functions. By prefixing a call to a constructor function with the ‘new’ keyword we can tell the JavaScript runtime that we want the function to behave like a constructor and instantiate a new object containing the members defined by that function. Within a constructor function the ‘this’ keyword references the new object being created -  so a basic constructor function might be: function Person(name, age) { this.name = name; this.age = age; this.toString = function() { return this.name + " is " + age + " years old."; }; } var john = new Person("John Galt", 50); console.log(john.toString()); Note that by convention the name of a constructor function is always written in Pascal Case (the first letter of each word is capital). This is to distinguish between constructor functions and other functions. It is important that constructor functions be called with the ‘new’ keyword and that not constructor functions are not. There are two problems with the pattern constructor function pattern shown above: It makes inheritance difficult The toString() function is redefined for each new object created by the Person constructor. This is sub-optimal because the function should be shared between all of the instances of the Person type. Constructor Functions with a Prototype JavaScript functions have a special property called prototype. When an object is created by calling a JavaScript constructor all of the properties of the constructor’s prototype become available to the new object. In this way many Person objects can be created that can access the same prototype. An improved version of the above example can be written: function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { toString: function() { return this.name + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); In this version a single instance of the toString() function will now be shared between all Person objects. Private Members The short version is: there aren’t any. If a variable is defined, with the var keyword, within the constructor function then its scope is that function. Other functions defined within the constructor function will be able to access the private variable, but anything defined outside the constructor (such as functions on the prototype property) won’t have access to the private variable. Any variables defined on the constructor are automatically public. Some people solve this problem by prefixing properties with an underscore and then not calling those properties by convention. function Person(name, age) { this.name = name; this.age = age; } Person.prototype = { _getName: function() { return this.name; }, toString: function() { return this._getName() + " is " + this.age + " years old."; } }; var john = new Person("John Galt", 50); console.log(john.toString()); Note that the _getName() function is only private by convention – it is in fact a public function. Functional Object Construction Because of the weirdness involved in using constructor functions some JavaScript developers prefer to eschew them completely. They theorize that it is better to work with JavaScript’s functional nature than to try and force it to behave like a traditional class-oriented language. When using the functional approach objects are created by returning them from a factory function. An excellent side effect of this pattern is that variables defined with the factory function are accessible to the new object (due to closure) but are inaccessible from anywhere else. The Person example implemented using the functional object construction pattern is: var john = new Person("John Galt", 50); console.log(john.toString()); var personFactory = function(name, age) { var privateVar = 7; return { toString: function() { return name + " is " + age * privateVar / privateVar + " years old."; } }; }; var john2 = personFactory("John Lennon", 40); console.log(john2.toString()); Note that the ‘new’ keyword is not used for this pattern, and that the toString() function has access to the name, age and privateVar variables because of closure. This pattern can be extended to provide inheritance and, unlike the constructor function pattern, it supports private variables. However, when working with JavaScript code bases you will find that the constructor function is more common – probably because it is a better approximation of mainstream class oriented languages like C# and Java. Inheritance Both of the above patterns can support inheritance but for now, favour composition over inheritance. Summary When JavaScript code exceeds simple browser automation object orientation can provide a powerful paradigm for controlling complexity. Both of the patterns presented in this article work – the choice is a matter of style. Only one question still remains; who is John Galt?

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  • Javascript - find swfobject on included page and call javascript function

    - by Rob
    I’m using the following script on my website to play an mp3 in flash. To instantiate the flash object I use the swfobject framework in a javascript function. When the function is called the player is created and added to the page. The rest of the website is in php and the page calling this script is being included with the php include function. All the other used scripts are in the php 'master'-page var playerMp3 = new SWFObject("scripts/player.swf","myplayer1","0","0","0"); playerMp3.addVariable("file","track.mp3"); playerMp3.addVariable("icons","false"); playerMp3.write("player1"); var player1 = document.getElementById("myplayer1"); var status1 = $("#status1"); $("#play1").click(function(){ player1.sendEvent("play","true"); $("#status1").fadeIn(400); player4.sendEvent("stop","false"); $("#status4").fadeOut(400); player3.sendEvent("stop","false"); $("#status3").fadeOut(400); player2.sendEvent("stop","false"); $("#status2").fadeOut(400); }); $("#stop1").click(function(){ player1.sendEvent("stop","false"); $("#status1").fadeOut(400); }); $(".closeOver").click(function(){ player1.sendEvent("stop","false"); $("#status1").fadeOut(400); }); $(".accordionButton2").click(function(){ player1.sendEvent("stop","false"); $("#status1").fadeOut(400); }); $(".accordionButton3").click(function(){ player1.sendEvent("stop","false"); $("#status1").fadeOut(400); }); $(".turnOffMusic").click(function(){ player1.sendEvent("stop","false"); $("#status1").fadeOut(400); }); }); I have a play-button with the id ‘#play1’ and a stop-button with the id ‘#stop1’ on my page. A div on the same page has the id ‘#status1’ and a little image of a speaker is in the div. When you push the playbutton, the div with the speaker is fading in and when you push the stopbutton, the div with the speaker is fading out, very simple. And it works as I want it to do. But the problem is, when a song is finished, the speaker doesn’t fade out. Is there a simple solution for this? I already tried using the swfobject framework to get the flash player from the page and call the ‘IsPlaying’ on it, but I’m getting the error that ‘swfobject’ can’t be found. All I need is a little push in the right direction or an example showing me how I can correctly get the currently playing audio player (in flash), check if it’s playing and if finished, call a javascript function to led the speaker-image fade-out again. Hope someone here can help me

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  • Need to lookup function arguments (in/out) from pdb by dbghelp

    - by Usman
    I need to lookup function parameters(their types infact) from PDB file From dbghelp, we can parse any pdb and can get info like how many functions,addresses function names and others etc. My problem is I am also interested to get function parameters as well. As SYMBOL_INFO structure in callback function only contains symbolName,Addresses and Size. How can we lookup PARAMETERES(in/out Types/names)of any function. Regards Usman

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  • Erlang function does not exist in module?

    - by Sepehr Samini
    In lager.elr (the main module of https://github.com/basho/lager) there is no function with name "debug" but I have an application that call debug function from lager module like: lager:debug(Str, Args) I am beginner in Erlang but I know when we call a function from a module lile "mymodule:myfunction" there should be a function with name "myfunction" in file mymodule.erl but in this case when I search in lager.erl for function "debug" I can't find it.

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