Where statement

[Michel Fortin]

On 2010-07-25 09:48:21 -0400, bearophile <bearophileHUGS at lycos.com> said:

> Michel Fortin:
>> Is this really an improvement over using a delegate literal?
>> 
>> 	auto c = {
>> 		auto a = retrieve_a();
>> 		auto b = retrieve_b();
>> 		return sqrt(a*a + b*b);
>> 	};
> 
> Cute :-) I have never seen this used in D code. I think you will need 
> to add () at the end when @property  get implemented fully.

Indeed, I forgot to add the (). Without it the type of 'c' is a 
delegate (whether @property is implemented or not is irrelevant). I 
just didn't test it properly before posting. Here's the revised version:

	auto c = {
		auto a = 1.0;
		auto b = 2.0;
		return a*a + b*b;
	}();

I've never seen this in use either, but it looks like a nice pattern 
for variables that require a complex initialization.


> I hope the D compiler is able to inline that delegate.

I think it does not currently. This bug report turns out to have a 
patch for this exact issue however:
<http://d.puremagic.com/issues/show_bug.cgi?id=4440>

Put your vote on it if you want.

-- 
Michel Fortin
michel.fortin at michelf.com
http://michelf.com/