[Issue XXX] ToBeFiled: 'this' can't be used as an alias parameter for a mixin

Bill Baxter wbaxter at gmail.com
Sat Dec 16 09:50:09 PST 2006


[I'll file this for real once Bugzill is back]

This may not be a bug for some technical reason unbeknownst to me that 
the spec mentions, but I found it unexpected.  You can't use 'this' as 
an alias paramter to a mixin in a class member function.  The workaround 
is pretty easy, you just assign it to a local dummy variable, and use 
that instead.


import std.stdio : writefln;

template printer_mix(alias T)
{
     void print() {
         writefln(T);
     }
}

class Foo
{
     void dump() {
         // Error: mixin printer_mix!(this) does not match any template 
declaration
         mixin printer_mix!(this);

         // this version ok:
         //Foo x = this;
         //mixin printer_mix!(x);

         print();
     }
     char[] toString() { return "I'm Batman"; }
}

void main()
{
     Foo f = new Foo();
     f.dump();
}


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