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The following code won't compile. Why? class A { int j; void f( int i = this->j ); } Edit, for clarity. This is what I was trying to do, using less lines of code... class A { void f( int i ){}; void f( ); int j; }; void A::f() { f( j ); } Eric Default argument values are bound at compile time. "this" is only defined at run time, so can't be used. See here for a fuller explanation: Must default function parameters be constant in C++? Others have already commented on the reason this doesn't work. From one of the comments: "...The expression can combine functions that are visible in the current

In C++, an object refers to itself via this . But how does an instance of an inner class refer to the instance of its enclosing class? class Zoo { class Bear { void runAway() { EscapeService::helpEscapeFrom ( this, /* the Bear */ ??? /* I need a pointer to the Bear's Zoo here */); } }; }; EDIT My understanding of how non-static inner classes work is that Bear can access the members of its Zoo , therefore it has an implicit pointer to Zoo . I don't want to access the members in this case; I'm trying to get that implicit pointer. BЈовић Unlike Java, inner classes in C++ do not have an implicit

I am interested to know the difference between this and base object in C# . What is the best practice when using them? this represents the current class instance while base the parent. Example of usage: public class Parent { public virtual void Foo() { } } public class Child : Parent { // call constructor in the current type public Child() : this("abc") { } public Child(string id) { } public override void Foo() { // call parent method base.Foo(); } } The two keywords are very different. this refers to the current instance (not the “current class”). It can only be used in non-static methods

In a class constructor, I am trying to use: if(theObject != null) this = theObject; I search the database and if the record exists, I use theObject generated by Hibernate Query. Why can't I use this ? this is not a variable, but a value. You cannot have this as the lvalue in an expression. It's because 'this' is not a variable. It refers to the current reference. If you were allowed to reassign 'this', it would no longer remain 'this', it would become 'that'. You cannot do this. Because you can't assign to this . this represents the current object instance, i.e. yourself. You can consider this

In C++ , during a class constructor, I started a new thread with this pointer as a parameter which will be used in the thread extensively (say, calling member functions). Is that a bad thing to do? Why and what are the consequences? My thread start process is at the end of the constructor. The consequence is that the thread can start and code will start executing a not yet fully initialized object. Which is bad enough in itself. If you are considering that 'well, it will be the last sentence in the constructor, it will be just about as constructed as it gets...' think again: you might derive

var UI$Contract$ddlForm_change = function() { //'this' is currently the drop down that fires the event // My question is can I change the context so "this" represents another object? this = SomeObject; // then call methods on the new "this" this.someMethod(someParam); }; is this possible? James No, it's not possible. You can call a method with a specified value for this (using method.apply() / method.call() ) but you cannot re-assign the keyword, this . You can't change what this refers to from inside the function. However, you can call a function in a specific context - so that this refers to

Eclipse will give an error, "The left-hand side of an assignment must be a variable", when I try something like: public class Thing{ String a1; int a2; public void meth(){ Thing A = new Thing(); this = A; } } I had to assign each variable ( this.a1 = A.a1; this.a2 = A.a2; ) as a work around. Are there other ways to do this without going through each variable field? And if this is not a variable what is it called? this is a pseudo-variable that points to the current instance of the object, it can not be reassigned. It's also considered a keyword in the language, according to section §3.9 of the