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digitalmars.D.bugs - [Issue 3666] New: Enhancement Request: Mixin Templates

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=3666

           Summary: Enhancement Request: Mixin Templates
           Product: D
           Version: future
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: simen.kjaras gmail.com



PST ---
Currently, whenever you write a template to be mixed into another type, you
specify at the other type how to use the template. Most templates that are made
to be mixed in, will not be used in any other way. Hence, I propose that
templates may marked 'mixin' at declaration point, and 'mixin' be deemed
unnecessary at their point of use. 'mixin' should still be usable for unadorned
templates, and should be a no-op for mixin templates.

Proposed syntax:

mixin template foo( T ) {
  T x;
}

struct bar {
  foo!( int );
}

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Jan 02 2010
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=3666


Nick Sabalausky <cbkbbejeap mailinator.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |cbkbbejeap mailinator.com



13:08:19 PST ---
A two-part addendum:

1. As D's CTFE improves, there's been more and more reason to generate a string
mixin using CTFE instead of a template. Simen's point that "Most templates that
are made to be mixed in, will not be used in any other way" is also true for
CTFE functions. So this enhancement request should also be extended to CTFE
functions in addition to templates:

-----------------------
mixin string foo2() {
    return "int a;";
}
foo2();
a = 7;
-----------------------

2. It is probably worth noting that this enhancement request can be used to
trivially re-implement the current string mixin:

-----------------------
mixin string mixinString(string str) {
    return str;
}
mixinString("int a;");
-----------------------

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Feb 05 2010
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=3666


Andrej Mitrovic <andrej.mitrovich gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |andrej.mitrovich gmail.com
         Resolution|                            |INVALID



19:47:38 PDT ---
I don't know if D had mixins or template mixins back in 2010, these look like
old ideas (?). Reopen if necessary.

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Oct 21 2012
prev sibling parent d-bugmail puremagic.com writes:
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Jacob Carlborg <doob me.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |doob me.com



These are still valid ideas and D did had templates back in 2010. Half of the
proposal is already implemented, you can prefix a template declaration with
"mixin". When a template is prefix with "mixin" you cannot use it like a
regular template. But you still need the "mixin" keyword when mixing in the
template.

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