Pascal gets closures before java - why hasn't the world ended?
So I see Delphi now has generics and closures in its upcoming "Tiburon" release:
type // method reference TProc = reference to procedure(x: Integer); procedure Call(const proc: TProc); begin proc(42); end;
Use:
var
proc: TProc;
begin
// anonymous method
proc := procedure(a: Integer)
begin
Writeln(a);
end;
Call(proc);
readln
end.
I'd have loved have had both of these features back in the day when I was still doing Delphi. As much as I no longer like the Pascal syntax, I love how cleanly the anonymous method declaration sits within the natural flow of things (although I'm not sure an inline method directly on the call to Call() would sit well).
My only question is, if Pascal can evolve why can't java?
Sure the Tiburon release can do this because the underlying .NET VM now supports the functionality, but thats not the point. Ok?
I'm sure Java will get some form of closure/anonymous function sometime.
Whether it will be ghastly is a large possibility, though.
Closure is a cool feature. It has made a way to PHP 5.3 already.
I'm skeptical about how useful closures will be after they are introduced
in java.
I'm afraid people will get carried away and misuse the feature, I have a
similar feeling about java reflection.
As far as I know closures in JAVA are now under discussion. And for know
the inner class are used as some sort of closures.
That example doesn't display use of closures. No state was carried by the
method object - it didn't "close around" any values.
It will be even better than you think.
Anonymous method and generics will be added also to native Delphi (not Net
version).
So it is done without net vm help.
Delphi has had inner functions that can refer to their enclosing lexical
scope since at least 5.0. Unfortunately, you couldn't take the address of
them.
Disclosure: I'm an engineer working on the Delphi compiler, and I've been
primarily responsible for the implementation of anonymous methods (as we're
calling our version of closures).
The new anonymous method in Delphi has no relation to the .NET since
Tiburon will be a release that will entirely focus on Win32.... It seams
this is the first step towards a LINQ style enabling in both Win32 & .NET
Delphi ...
I agree with Shams, and to continue I personally don't think it belongs in
an OO Language like Java. I am still finding it pretty hard to figure out
what benefits a closure provides over a simple private method....