http://d.puremagic.com/issues/show_bug.cgi?id=1672

           Summary: Literals should match template alias arguments
           Product: D
           Version: 2.007
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: andrei@metalanguage.com


Consider an implementation of a sort function with configurable comparison:

template sort(alias comparison)
{
   ... define a sort function ...
}

A candidate for "comparison" is a function, e.g.:

bool less(int a, int b) { return a < b; }
sort!(less)(array);

Let's say we want to make sort take a compile-time string that contains the body of the comparison, such that:

sort!("a < b")(array);

has the same effect as the more verbose version above. (By convention, the string names the compared objects "a" and "b".) The compiler does not accept the string literal; it won't match a literal. What it does accept is:

static const string less = "a < b";
sort!(less)(array);

The problem is that we got back to the same verbosity as before. Since this is likely to become a very useful idiom, the compiler should automatically transform a compile-time value passed as an alias into an anonymous alias.


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http://d.puremagic.com/issues/show_bug.cgi?id=1672





------- Comment #1 from shro8822@vandals.uidaho.edu  2007-11-15 13:30 -------
What does this have over:

template sort(char[] comp)

are you hoping to be able to pass either a string or a function?


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1672





------- Comment #2 from andrei@metalanguage.com  2007-11-15 13:33 -------
(In reply to comment #1)
> What does this have over:
> 
> template sort(char[] comp)
> 
> are you hoping to be able to pass either a string or a function?

Yes, the point is to pass either a string, a function, a delegate, or a struct/class, and have the sort template discern how to proceed with static if's.


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1672





------- Comment #3 from shro8822@vandals.uidaho.edu  2007-11-15 13:37 -------
How do you plan to pass delegates? I have wanted to pass local values to a template but couldn't find a way to do it.


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http://d.puremagic.com/issues/show_bug.cgi?id=1672





------- Comment #4 from samukha@voliacable.com  2008-11-13 01:56 -------
Can we set this one to fixed?


-- 

http://d.puremagic.com/issues/show_bug.cgi?id=1672


andrei@metalanguage.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED




------- Comment #5 from andrei@metalanguage.com  2008-11-13 08:04 -------
(In reply to comment #4)
> Can we set this one to fixed?
> 

Yah, I think so.


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