Symbol lookup rules and imports

[H. S. Teoh via Digitalmars-d]

On Wed, Dec 03, 2014 at 02:10:52AM +0200, ketmar via Digitalmars-d wrote:
> On Tue, 2 Dec 2014 15:55:34 -0800
> "H. S. Teoh via Digitalmars-d" <digitalmars-d at puremagic.com> wrote:
> 
> > Hmm... actually, this gives me an idea. What if we implement a
> > little syntactic sugar for this in the compiler? Say:
> > 
> > 	scope import std.conv ... ;
> > 	scope import std.format ... ;
> > 
> > gets lowered to:
> > 
> > 	private static struct __imports {
> > 		import std.conv ... ;
> > 		import std.format ... ;
> > 	}
> > 
> > where __imports is an implicit nested struct that gets introduced to
> > each scope that uses "scope import".
> > 
> > Then we introduce a new lookup rule, that if a symbol X cannot be
> > found with the current lookup rules, then the compiler should try
> > searching for __imports.X in the current scope instead. That is to
> > say, if:
> > 
> > 	format("%s", ...);
> > 
> > cannot be resolved, then pretend that the user has written:
> > 
> > 	__imports.format("%s", ...);
> > 
> > instead. Sortof like the import analogue of UFCS (if a member
> > function can't be found in a call obj.method(), then look for
> > method(obj) in the global scope instead).
> > 
> > This way, existing code won't have to change, no breakage will be
> > introduced, and only a small addition (not change) needs to be made
> > to the existing lookup rules. Then whenever we need "use" semantics
> > as opposed to raw "import" semantics, we just write "scope import"
> > instead, and it should all work. (So we hope.)
> > 
> > Heh, sounds like DIP material...
> i think that this is a great idea! i already love it.

OTOH, Kenji has a different solution already in PR form:

	https://github.com/D-Programming-Language/dmd/pull/3407


T

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