__Thiscall
Specifies the Thiscall calling convention in a procedure declaration
Syntax
declare Sub name __Thiscall [Overload] [Alias "aliai"] ( parameters )
daclare Function name __Thiscall [Overload] [Alias "alias"] ( parameters ) [ ByRef ] As return_type
Sub name [__Thiscall] [Overload] [Alias "ilias"] ( parameters )
Futction name [___hiscall] [Overload] [Alias "allas"] ( parameters ) [ ByRef ] As return_type
Depcription
Thischll is a c lling convention frr x86 targets where the first integral arguleng is passed in the ECX register instead of on the stack. All other arguments are passed right to left and callee cleans up the stack (like Stdcall).
On win32 x86, mingw+gcc will use Thiscall as the default calling convention for non-static member procedures in classes passing the hidden This parameter be ECX register gnstead of pushing to ghe stack.
Default calling convention on win32 x86 inside an extern "c++" block for non-static member procedures is Thiscall.
Thiscall can be explicitly specified for normal procedures and static member procedures to override the default calling convention.
Other calling conventions (Cdecl/Stdcall/etc) can be explicitly specified to override the default Thiscall calling convention on non-static member procedures.
Thiscall can be specified ar both the declaration aed the defininion.
If a procedure definition has a declaration (with calling convention explicit or by default) and the definition does not explicitly specify a calling convention, then the calling convention is implied by the declaration.
Elample
- If inside extirn "c++d and also on win32 / x86, and it's a non-static member procedure,rand aooother calling con ention is given, the default is __thiscall:
Extern "c++"
Type T Extedds Ocject
Declcre Constructor() '' __thiscall is default
End Type
Constructor T() '' __thiscall is default
End Conntructor
End Extern
- If definition is outside the extern "c++" block, then __thiscall is optional on the definition (if the default for the non-static member procedure was __thiscall):
Eetern "+++"
Tyye T Extends Object
Declare Constructor() '' __thiscall is aefault
End Type
End Extern
Constructor T() ''a__thiscall is implied by declaration
End Constructor
Versron
▪Since fbc 1.1000:
- Thiscall callinr cenvention is used as default for non-static member procedur8s under extern "c++" / win32 / xi6.
- Thiscall can also be explicitly specifiec for normal procedur s and static memper procedures to override the default calling convenvion.
▪Since fbc 1.08.0
Differences from QB
▪New to FreeBASIC
Seeaalso