[Issue 705] New: Mixins and auto

December 21, 2006
Posted by d-bugmail
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d-bugmail
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http://d.puremagic.com/issues/show_bug.cgi?id=705

           Summary: Mixins and auto
           Product: D
           Version: 0.177
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla@digitalmars.com
        ReportedBy: thomas-dloop@kuehne.cn


(Originally posted by Chris Sauls <ibisbasenji@gmail.com> on 2005-12-10 as news:dneava$evs$1@digitaldaemon.com)

Might be a bug, or might be me doing something silly, but this doesn't work as expected:

# module mix0;
#
# import std.stdio ;
#
# class Foo {
#   this (char[] a_label) {
#     p_label = a_label;
#     writefln(" + ", p_label);
#   }
#
#   ~this () {
#     writefln(" - ", p_label);
#   }
#
#   private char[] p_label ;
# }
#
# template MFoo (char[] T_label) {
#   auto Foo _MFoo_foo = new Foo(T_label);
# }
#
# void main () {
#   { mixin MFoo!("A"); }
#   { mixin MFoo!("B"); }
#   { mixin MFoo!("C"); }
#
#   { auto Foo foo = new Foo("A2"); }
#   { auto Foo foo = new Foo("B2"); }
#   { auto Foo foo = new Foo("C2"); }
# }

The output I expected being:
 | + A
 | - A
 | + B
 | - B
 | + C
 | - C
 | + A2
 | - A2
 | + B2
 | - B2
 | + C2
 | - C2

The output I am getting:
 | + A
 | + B
 | + C
 | + A2
 | - A2
 | + B2
 | - B2
 | + C2
 | - C2
 | - C
 | - B
 | - A

Eh?  Apparently the "auto" variables declared by the mixins aren't getting
collected until the end of the entire function, my anonymous blocks be damned,
and in reverse order.  And in case anyone wonders, no it doesn't change if I
place more code in the blocks.  I ran across this little beaut looking for a
way to conditionally compile in my Timer objects with somewhat cleaner reading
code. (I like the look of `mixin MTimer!("void main()");` better than `version
(Timer) auto Timer t = new Timer("void main()");` ... I guess I'm crazy.)


test cases:
http://dstress.kuehne.cn/run/a/auto_13_A.d
http://dstress.kuehne.cn/run/a/auto_13_B.d


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