I often miss some features of functional programming languages when coding in imperative / oo languages. But i really love D, so i had to write something that allows me to use partial application in D.

What i always wanted to do was: Give another object a delegate which has a part of it's parameters already given, like this:

void Update(Child c, int a, int b, int c) { ... }

child.OnUpdate = &this.Update(child);

Where the Child wouldn't be able to tell the difference between this (partially applied) delegate and a delegate of type "void delegate(int,int,int).

The AdvancedDelegate templates solve this in a type-safe manner. The only problem remaining was: i had to write different templates for a different number of parameters. Since this would have been very repetative, i hacked together a PHP script that does this for me. Now you can do something like:

child.OnUpdate = new AdvancedDelegateP4G1!(void,Child,int,int,int)(&this.Update, child);

Where child.OnUpdate would be of the type "AdvancedDelegate3!(void,int,int,int);"

For more examples, see the "demo.d" file.

The attached ZIP file contains a script (written in PHP because i just hacked it together) that generates the "advanceddelegate" library for any given number of parameters. Since not everyone uses PHP, i generated the library for up to 10 parameters.

You can use delegates and functions with this library, they are fully interchangeable.

If this is useful in any way, please provide me some feedback - without feedback i wont be in the mood to develop it any further than it is now ;)

I think it's pretty cool. My only suggestion is to ditch the php script and write a D script to do the same thing!

Walter Bright schrieb:
> I think it's pretty cool. My only suggestion is to ditch the php script and write a D script to do the same thing!

I only wrote it today, i used PHP because i can hack it so damn fast. The script is a mess, especially the variable names :)

So writing a nice d script will be the next step!

IMPORTANT UPDATE:
I suddenly realised how helpful the auto keyword is, and i added a few
helper functions to make things even more easier. You can now write:

auto add = AdvancedFunction(
	function int(int a, int b) { return a+b; }
);
writeln("add(2,2): ", add(2)(2).Eval);

The same goes for delegates, except i had to call the helper template "AdvancedDelegate". Seems i cant overload two templates like this:

AdvancedDelegate0!(R) AdvancedDelegate(R) (R delegate() dg)
{
     return new AdvancedDelegateP0G0!(R)(dg);
}

AdvancedDelegate0!(R) AdvancedDelegate(R) (R function() dg)
{
     return new AdvancedFunctionP0G0!(R)(dg);
}

But i don't think it is a big problem.

Walter Bright schrieb:
> I think it's pretty cool. My only suggestion is to ditch the php script and write a D script to do the same thing!

Ok, here it is!
Changes:
   - added opCall() as a shortcut for Eval() in AdvancedDelegate0
   - the library is now generated by a D script instead of a PHP script
   - removed most of the aliases in "all.d" as they aren't needed when
you use the helpers

"Walter Bright" <newshound@digitalmars.com> wrote in message news:e6nhnp$1cd5$2@digitaldaemon.com...
>I think it's pretty cool. My only suggestion is to ditch the php script and write a D script to do the same thing!

Or if you added variable template parameters we wouldn't need a script at all :)

-Craig