Function Pointer

• Function pointer can only be created by referencing a static method.

• Function pointer can not be dereferenced.

Reference

See: Function pointers

Declaration

delegate*<void> f = &M;
delegate*<int, void> g = &N;
static void M() { }
static void N(int a) { }

Invocation

A function pointer is a pure reference to the function without the delegate wrapper. There's no member of it to be accessed using ., can only be invoked by ();

delegate*<void> f = &M;
delegate*<int, void> g = &N;
f(); g(default);
static void M() { }
static void N(int a) { }

Type parameter variant

delegate*<int, int, int> h = &O;
delegate*<char*, int*, int*> i = &P;
static int O(int a, int b) => default;
static unsafe int* P(void* m, int* b) => default;

Operator

Calling Conventions

managed

• managed is the default calling convention of a function pointer.

delegate*<void> f = &M;
delegate* managed<void> g = &M;
static void M() { }

unmanaged

• Cdecl

• Stdcall

• Fastcall

• Thiscall

• Default unmanaged calling convention

The default unmanaged calling convention is left to CLR to make the decision.

public unsafe static void M<T>(delegate* unmanaged<T> f) { }

Type Checking

Type checking of two function pointer includes function signatures and their calling convention.

delegate*<void> f = &M;
delegate* managed<void> g = &N;
delegate* unmanaged<void> h = ...;
f = g;
g = h; // calling convention not matched!
static void M() { }
static void N() { }