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digitalmars.D.bugs - [Issue 2913] New: aliasing a ref type is not possible

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2913

           Summary: aliasing a ref type is not possible
           Product: D
           Version: unspecified
          Platform: PC
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: andrei metalanguage.com


alias ref int rint;

rint foo() { static int x; return x; }

void main()
{
    auto p = &(foo());
}

This doesn't work. It led me to write the ugliest code I have ever written.
Search std.range for "mixin" if you want to see ugly stuff.


--
Apr 29 2009
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2913






-------
I'm not sure allowing that alias is a good idea, as ref int and int still name
the same type. If that alias worked, wouldn't you expect

alias ref int rint;
int i = 3;
rint ri = i;
ri = 4;
assert(i == 4);


--
Apr 30 2009
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2913








 I'm not sure allowing that alias is a good idea, as ref int and int still name
 the same type. If that alias worked, wouldn't you expect
 
 alias ref int rint;
 int i = 3;
 rint ri = i;
 ri = 4;
 assert(i == 4);
 


The ref would be only effective in a function signature. This can be done (I
discussed it with Walter). The problem is, Walter has a lot on his plate
already. Yet that doesn't make my code look any better :o).


--
Apr 30 2009
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2913






dup of bug 2753?


--
May 04 2009
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=2913


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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrej.mitrovich gmail.com



10:45:12 PST ---




 I'm not sure allowing that alias is a good idea, as ref int and int still name
 the same type. If that alias worked, wouldn't you expect
 
 alias ref int rint;
 int i = 3;
 rint ri = i;
 ri = 4;
 assert(i == 4);
 


 
 The ref would be only effective in a function signature.


So would that code error at compile-time or just silently compile and fail at
runtime as if the ref didn't exist? It's tricky business..

But there's definitely a problem of not being able to pass around 'ref' in
metaprogramming. The classic example being std.signal, where you can't define a
signal with ref parameters:

struct S
{
    // would allow connecting to 'void f(ref int) { }'
    mixin Signal!(ref int);
}

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