www.digitalmars.com         C & C++   DMDScript  

digitalmars.D.bugs - [Issue 1728] New: alias hides mixin member func?

reply d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1728

           Summary: alias hides mixin member func?
           Product: D
           Version: 2.008
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla digitalmars.com
        ReportedBy: davidl 126.com


import std.stdio;

interface mix 
{ 
        void print(char[]); 
}

template mixtem() 
{ 
        void print(char[] t) 
        { 
                writefln(t); 
        } 
}

class A
{ 
        void print() 
        { 
                writefln("A"); 
        } 
        void print(int a) 
        { 
                writefln(a); 
        } 
}

class B:A,mix 
{
        alias A.print print;    
        mixin mixtem; 
        void pr() 
        { 
                super.print(); 
                super.print(18); 
                print("OK");   // this should call mixin member func
                writefln("B"); 
        } 
}

kk.d(36): function kk.A.print () does not match parameter types (char[2u])


--
Dec 11 2007
next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1728


davidl 126.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |patch





a patch
in template.c
TemplateMixin::semantic
    // Declare each template parameter as an alias for the argument type
    declareParameters(scope);

++  ScopeDsymbol *parent = sc -> parent;

    // Add members to enclosing scope, as well as this scope
    for (unsigned i = 0; i < members->dim; i++)
    {   Dsymbol *s;

        s = (Dsymbol *)members->data[i];
+++     // for fixing bug 1728
http://d.puremagic.com/issues/show_bug.cgi?id=1728
+++     // actually we provide the sugar of introducing the funcdeclaration
transparently from this anonymous scope

+++     if (s -> isFuncDeclaration())
+++     {
+++         s->addMember(scope, parent, i);
+++         s->parent = this;
+++     }
+++     else
        s->addMember(scope, this, i);
        //sc->insert(s);
        //printf("sc->parent = %p, sc->scopesym = %p\n", sc->parent,
sc->scopesym);
        //printf("s->parent = %s\n", s->parent->toChars());
    }

and in dsymbol.c:
Dsymbol::addMember

            s2 = sd->symtab->lookup(ident);
+++         s2 = s2 -> toAlias();
            if (!s2->overloadInsert(this))
            {
                sd->multiplyDefined(0, this, s2);
            }


--
Jun 25 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1728






in the patch

+++     if (s -> isFuncDeclaration())
+++     {
+++         s->addMember(scope, parent, i);
+++         s->parent = this;
+++     }
+++     else

should be 
+++     if (s -> isFuncDeclaration() && parent != NULL )
+++     {
+++         s->addMember(scope, parent, i);
+++         s->parent = this;
+++     }
+++     else


--
Jul 07 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1728


bugzilla digitalmars.com changed:

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





This is not a bug.

The mixin establishes its own scope that is nested inside B's scope. If there
is no print in B's scope, it will look in the mixin. If there is a print in B's
scope, it will not look in the mixin.

This works exactly the same as imports and symbols at module scope.

The solution is to bring the desired members of mixtem up into B's scope. An
alias will accomplish this, so rewriting B as:

class B:A,mix 
{
        alias A.print print;    
        mixin mixtem M;        // give scope the name 'M'
        alias M.print print;   // and bring M's print into B's scope
        void pr() 
        { 
                super.print(); 
                super.print(18); 
                print("OK");   // this should call mixin member func
                writefln("B"); 
        } 
}

should work.


--
Dec 09 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1728








 This is not a bug.
 
 The mixin establishes its own scope that is nested inside B's scope. If there
 is no print in B's scope, it will look in the mixin. If there is a print in B's
 scope, it will not look in the mixin.
 
 This works exactly the same as imports and symbols at module scope.
 
 The solution is to bring the desired members of mixtem up into B's scope. 


That works fine for normal methods, but how about ctors?  I actually ran into
this.

template mixtem()
{ 
        this(char[] t)
        {
                Stdout.formatln(t);
        }
}

class A
{
        mixin mixtem;

        this()
        {
                this("OK"); // same error as the OP
        }
}

Except of course "mixin mixtem M; alias M.this this;" is not legal.  (I also
tried using the weird _ctor but that doesn't work either.)


--
Dec 09 2008
prev sibling next sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1728






I suspect that trying to make this work would add a bunch of arcane rules with
little benefit. Instead, try to remove what this(string) does to a separate
function, then call that function from the other this().


--
Dec 09 2008
prev sibling parent d-bugmail puremagic.com writes:
http://d.puremagic.com/issues/show_bug.cgi?id=1728






But I can't accept that:
class B:A,mix 
{
        mixin mixtem; 
        void pr() 
        { 
                print("OK");   // this should call mixin member func
                writefln("B"); 
        } 
}

works

while:

class B:A,mix 
{
        alias A.print print;    
        mixin mixtem; 
        void pr() 
        { 
                print("OK");   // this should call mixin member func
                writefln("B"); 
        } 
}

doesn't work.

An alias shouldn't hide a func that I try to call.


--
Dec 11 2008