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In C++ 5.1.1/3 [expr.prim.general] it says:
The type and value category [of
this] are defined within a static member function.
What does this mean? How is it relevant?
Note that:
thisshall not appear in the declaration of a static member function
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The static member functions are special functions used to access the static data members or other static member functions. A member function is defined using the static keyword. A static member function shares the single copy of the member function to any number of the class' objects.
No, the "this" keyword cannot be used to refer to the static members of a class. This is because the “this” keyword points to the current object of the class and the static member does not need any object to be called.
Static member functions are called using the class name. Syntax- class_name::function_name( )
The language in the standard can be traced to n3282, which is a resolution for defects 1207 and 1017. In particular, the language appears in the proposed resolution for defect 1207, and thus should be considered in the context of the standard as it stood at the time that defect was addressed. At that time there was some concern over the rewriting of id-expressions into member access expressions using *this (9.3.1p3), in particular in the context of trailing-return-type declarations (see issue 945).
If we compare the proposed resolution to defect 1207 to the eventual language in n3282 and subsequently in the standard, there is one significant difference to 9.3.1p3:
When an id-expression (5.1 [expr.prim]) that is not part of a class member access syntax (5.2.5 [expr.ref]) and not used to form a pointer to member (5.3.1 [expr.unary.op]) is used in the declaration of a member function of class
X, if name lookup (3.4 [basic.lookup]) resolves the name...
When an id-expression (5.1 [expr.prim]) that is not part of a class member access syntax (5.2.5 [expr.ref]) and not used to form a pointer to member (5.3.1 [expr.unary.op]) is used in a member of class
Xin a context wherethiscan be used (5.1.1 [expr.prim.general]), if name lookup (3.4 [basic.lookup]) resolves the name [...]
It is apparent that the proposed resolution to defect 1207 carried the belief that id-expressions (to a static member) within a static member functions would need to be transformed to *this member access expressions and thus would need access to the type and value category of this. By the time n3282 was written this had been resolved in favour of the qualified-id transformation (also 9.3.1p3) which does not require this, but the language in 5.1.1p3 remained vestigially.
I would recommend raising this issue on the C++ standards discussion newsgroup; it may be possible to get the vestigial language removed editorially.
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