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How does function overloading work at run-time, and why overload?

由 生来就可爱ヽ(ⅴ＜●) 提交于 2019-12-07 07:05:19
问题 Let's say I have a class named ClothingStore. That class has 3 member functions, that point a visitor to the right department of the store. Member functions are ChildrenDept, MenDept and WomenDept, depending on whether the visitor is a child, a man or a woman. Function overloading can be used to make 3 functions that have same name, say, PointToDept, but take different input argument ( child, man, woman ). What is actually happening on run-time when program is executing ? My guess is that

Member function definition

由 天涯浪子 提交于 2019-12-07 02:53:25
问题 What is the right approach to take: Define the member (class) function inside the class? Define the member (class) function outside the class? Thanks. 回答1: Assuming you're talking about these three possibilities: Method defined in class definition in header file. Method define outside class definition in header file. Method define outside class definition in implementation file. Then project and company guidelines may force you to use (1) or (3) always. When you have a choice, it's IMHO best

To inline or not to inline

由 不羁岁月 提交于 2019-12-06 20:14:41
问题 I've been writing a few classes lately; and I was wondering whether it's bad practice, bad for performance, breaks encapsulation or whether there's anything else inherently bad with actually defining some of the smaller member functions inside a header (I did try Google!). Here's an example I have of a header I've written with a lot of this: class Scheduler { public: typedef std::list<BSubsystem*> SubsystemList; // Make sure the pointer to entityManager is zero on init // so that we can check

How to call the __invoke method of a member variable inside a class

由 送分小仙女□ 提交于 2019-12-06 19:52:14
问题 PHP 5.4.5, here. I'm trying to invoke an object which is stored as a member of some other object. Like this (very roughly) class A { function __invoke () { ... } } class B { private a = new A(); ... $this->a(); <-- runtime error here } This produces a runtime error, of course, because there's no method called a. But if I write the call like this: ($this->a)(); then I get a syntax error. Of course, I can write $this->a->__invoke(); but that seems intolerably ugly, and rather undermines the

Accessing a protected member variable outside a class

由 穿精又带淫゛_ 提交于 2019-12-06 18:19:35
问题 I'm querying for the ID of a field by accessing a class function which someone has already put in place. The result is a object returned with protected member variables. I'm struggling to see how I can access the member variable values outside the class. 回答1: Just add a "get" method to the class. class Foo { protected $bar = 'Hello World!'; public function getBar() { return $this->bar; } } $baz = new Foo(); echo $baz->getBar(); 回答2: Accessing protected or private variables from public is

Qt: Different tableWidget member names on workstations

由 点点圈 提交于 2019-12-06 11:36:33
I am using Qt on two ubuntu machines and am copying the source code from time to time between them. I found a really annoying problem when doing that and I can't figure out why this happens. I am using a table Widget to display some data and want to stretch the horizontal header to fit the content length. To do that I use the following line: ui->tableWidget->horizontalHeader()->setResizeMode(0, QHeaderView::ResizeToContents); This works just fine. I have a few of this codelines. However, when I now copy over my source code to the other PC to work on it, I get the following compile error:

Defining private static class member

由 北慕城南 提交于 2019-12-06 07:36:59
class B { /* ... */ }; class A { public: A() { obj = NULL; } private: static B* obj; }; However this produces huge mass of linker errors that symbol obj is unresolved. What's the "correct" way to have such private static class member without these linker errors? You need to define like this : this is in the header : class B { ... } class A { public: A() { obj = NULL; } private: static B* obj; } this is in the source B* A::obj = NULL; You need to add B *A::obj = NULL; to one of your cpp files. Also note that if you set obj in A's constructor, that means that whenever you create an A object you

Scope of Java class static member

由 萝らか妹 提交于 2019-12-06 06:20:28
问题 I am developing a web application using Java/JSP. One class, say Student, has a static member static private int _nextID; I want to know, if this _nextID is the same among all user sessions? Or each session has its own _nextID? 回答1: In the simple case , you can assume that multiple instances of Student will share the same static nextID field. However, one should think beyond the simple case (or document that you haven't). In this case, it's fine unless the instance id fields derived from the

LDAP group membership (including Domain Users)

由 亡梦爱人 提交于 2019-12-06 06:02:26
问题 How can I get a list of users within an LDAP group, even if that group happens to be the primary group for some users? For example, suppose "Domain Users" is "Domain Leute" in German. I want all members of "CN=Domain Leute,DC=mycompany,DC=com". How would I know that is the well-known "Domain Users" group? Or what if some users' primary group was changed to "CN=rebels,DC=mycompany,DC=com", and I wanted to get members of THAT group? Users don't have a memberOf property for their primary group,

Usage of objects or pointers to objects as class members and memory allocation

由 一世执手 提交于 2019-12-06 06:02:25
A similar question has been asked here: Class members that are objects - Pointers or not? C++ so I'll keep it brief. Say I have an object that contains three stl vectors. Is my thinking correct that if they are regular members of the class, the memory of them will be "together" for the whole object? e.g. my memory would look sth like 10 blocks vector A, 5 blocks vector B, and then 15 blocks vector C. Would then once I insert more objects into vector A so that the space runs out the whole structure including vector B and C need to be moved? Is that then an argument for pointers? Or are vectors
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