Hi folks,

I'm having trouble deciphering this function signature, which appears in the DIP9 proposal:

void writeTo(scope delegate(in char[] data) sink,
	     string format = null) const

// from http://prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP9

Particularly, how does "scope" modify the delegate, and what is the meaning of the trailing "const"?

Thanks,
Graham

Graham Fawcett:

> void writeTo(scope delegate(in char[] data) sink,
> 	     string format = null) const
> 
> // from http://prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP9
> 
> Particularly, how does "scope" modify the delegate, and what is the meaning of the trailing "const"?

"scope" means that the sink delegate is not a true closure, its outer scope is never allocated on the heap. "const" member functions means that inside it the "this" is const, so writeTo() can't modify the class/struct attributes.

Bye,
bearophile

On Fri, 19 Nov 2010 14:43:03 -0500, bearophile wrote:

> Graham Fawcett:
> 
>> void writeTo(scope delegate(in char[] data) sink,
>> 	     string format = null) const
>> 
>> // from http://prowiki.org/wiki4d/wiki.cgi?LanguageDevel/DIPs/DIP9
>> 
>> Particularly, how does "scope" modify the delegate, and what is the meaning of the trailing "const"?
> 
> "scope" means that the sink delegate is not a true closure, its outer scope is never allocated on the heap. "const" member functions means that inside it the "this" is const, so writeTo() can't modify the class/struct attributes.

Ah! Thanks very much, bearophile!

Graham