• d-bugmail puremagic.com (46/46) Jul 22 2012 http://d.puremagic.com/issues/show_bug.cgi?id=8409
• d-bugmail puremagic.com (10/10) Sep 09 2012 http://d.puremagic.com/issues/show_bug.cgi?id=8409

d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=8409

           Summary: Proposal: implement arr.dup in library
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: druntime
        AssignedTo: nobody puremagic.com
        ReportedBy: k.hara.pg gmail.com



If issue 8408 is fixed, we can use following dup function definition.

template hasMutableIndirection(T)
{
    enum hasMutableIndirection = !is(typeof({ Unqual!T t = void; immutable T u
= t; }));
}
static assert(!hasMutableIndirection!(int));
static assert(!hasMutableIndirection!(int[3]));
static assert( hasMutableIndirection!(Object));

 property auto dup(E)(inout(E)[] arr) pure  trusted
{
    static if (hasMutableIndirection!E)
    {
        auto copy = new E[](arr.length);
        copy[] = cast(E[])arr[];        // assume constant
        return cast(inout(E)[])copy;    // assume constant
    }
    else
    {
        auto copy = new E[](arr.length);
        copy[] = arr[];
        return copy;
    }
}

In above dup function,
- If E has some mutable indirections, returns inout(E) and has constant purity.
- If E has no mutable indirections, return E[] and has string purity.
  That means: return value is implicitly convertible to immutable(E)[] with
  issue 5081, and can make a immutable duplication from mutable array.

Finally, we can remove the duplication of built-in dup/idup.

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------

d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=8409


Kenji Hara <k.hara.pg gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull



https://github.com/D-Programming-Language/druntime/pull/298

-- 
Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email
------- You are receiving this mail because: -------