CODEWITHSUNDEEP
pythonc++classthis
isados
isados

Reputation: 73

Shouldn't there be a name-agnostic class pointer similar to 'this' pointer for member functions to refer to in C++?

In Python, there's a self variable that refers to the instance itself, and a cls object (for class methods) that refer to the class. In the same manner, there's a 'this' pointer pointing to the calling object; but I'm not aware of any pointer to the class itself, I'm familiar with using something like this...

ClassName::memberFunction(this)

But it's not what I want.

I guess it's pretty obvious that there's no such thing, given how constructors still make use of their class's name, but why not make it a feature in C++?

Upvotes: 1

Views: 149

Answers (3)

Jarod42
Jarod42

Reputation: 217810

C++ doesn't have this kind of keyword allowing something like:

class C
{
    Self(const Self&) = default;  // Not valid
    ~Self() = default; // Not valid
};

You could simulate it with MACRO:

class C
{
#define Self C
    Self(const Self&) = default;
    ~Self() = default;
#undef Self
};

but why not make it a feature in C++?

You can still try to create a proposal for that.

Whereas using it in class definition seems fine, using it outside seems problematic:

C::C(const C&) {} // Regular way

Self::Self(const Self&) {} // Which class ?
C::Self(const Self&) {}    // Mix C and Self

Upvotes: 1

Yakk - Adam Nevraumont
Yakk - Adam Nevraumont

Reputation: 275730

Inside a method of the class, the tokens

std::decay_t<decltype(*this)>

will evaluate to the type name of this.

Outside of a method there is no similar technique.

It isn't in the language, because nobody has gotten such a feature through the committee. It would take work.

A number of compilers have extensions that resolve to the "parent class". I'm unaware of a compiler that has the extension for "type of enclosing class".

Upvotes: 1

eerorika
eerorika

Reputation: 238401

but I'm not aware of any pointer to the class itself

A class is not an object, so there can not be a pointer to a class.

Within other member functions (i.e. the only places you may have access to this in the first place), you can refer to static member functions simply by their name:

struct S {
    static void foo(){}
    void bar() {
        foo();
    }
};

Upvotes: 1

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