[fpc-devel] Local classes and interfaces

[Blaise at blaise.ru]

Behind the scene, the Closures implementation declares classes and interfaces. And, because I strongly believe it to be conceptually the right way, such entities are declared in the innermost routine scope. For example,
-------8<-------
procedure Foo;
	type Local = reference to procedure;
begin
end;
-------8<-------
is essentially
-------8<-------
procedure Foo;
	type Local = interface
		procedure Invoke;
	end;
begin
end;
-------8<-------

FPC does not allow the user to declare local classes/interfaces†, and this shall remain so. However, in order to /internally/ support such entities, a couple of changes is required. I have those implemented, but, firstly, let us establish that the team is on board with the general idea.


† No idea why, but generic local classes/interfaces are accepted. However, FPC instantiates them in the global scope, which results in this wonderful bug:
-------8<-------
function Foo: TClass;
	type Cls<T> = class end;
begin
	result := Cls<Char>
end;

function Bar: TClass;
	type Cls<T> = class end;
begin
	result := Cls<Char>
end;

begin
	// BUG: 'FALSE'
	writeln( Foo() <> Bar() )
end.
-------8<-------

-- 
βþ