• "Lloyd Dupont" <ld-REMOVE galador.net> Jun 24 2011
• "Lloyd Dupont" <ld-REMOVE galador.net> Jun 24 2011
• "Lloyd Dupont" <ld-REMOVE galador.net> Jun 24 2011

"Lloyd Dupont" <ld-REMOVE galador.net> writes:

It's going to be long as I'm going to post all the code...
Basically there is a bug in the type system or __traits when the program is 
split in static lib and exe (as opposed to all in one).

My test case:
- I have a all in one console application which output "true true"
- I have a project with the exact same code split into a static lib and an 
exe and it output "false false"

The bug is that the output is different!

=== first the all in one, outputing "true, true" =========
module main;

import std.variant;
import std.stdio;
import std.metastrings : Format;
import std.traits;

public mixin template property(T, string name)
{
    mixin(Format!("private T _%s;
                   property public T %s() { return _%s; }
                   property public void %s(T value) { _%s = value; }", name,
name, name, name, name));
}

interface IInter
{
}

class Foo : IInter
{
    static this()
    {
        Compiled!(Foo, "FP");
        Compiled!(Foo, "Subfoo");
    }

     property public Foo FP() { return new Foo(); }
     property public void FP(Foo f) { }

    mixin property!(Foo, "Subfoo");
}

int main(string[] argv)
{
    return 0;
}
void Compiled(T, string memberName)()
{
    T t;
    writeln(mixin( "__traits(compiles, t." ~memberName ~" = (" 
~typeof(__traits(getMember, T, memberName)).stringof  ~").init)" ));
}
==============================================


now the splitted program, outputting "false, false"
whereas it should output "true, true" just like above, shouldn't it!?!

===== lib.d ====
module lib;

import std.variant;
import std.stdio;
import std.metastrings : Format;
import std.traits;

public mixin template property(T, string name)
{
    mixin(Format!("private T _%s;
                   property public T %s() { return _%s; }
                   property public void %s(T value) { _%s = value; }", name, 
name, name, name, name));
}

interface IInter
{
}

void Compiled(T, string memberName)()
{
    T t;
    writeln(mixin( "__traits(compiles, t." ~memberName ~" = " 
~typeof(__traits(getMember, T, memberName)).stringof  ~").init" ));
}
====== main.d =====
module main;

import lib;

class Foo : IInter
{
    static this()
    {
        Compiled!(Foo, "FP");
        Compiled!(Foo, "Subfoo");
    }

     property public Foo FP() { return new Foo(); }
     property public void FP(Foo f) { }

    mixin property!(Foo, "Subfoo");
}

int main(string[] argv)
{
    return 0;
}
===================== buildrun.bat =========
dmd -lib -g -debug -X -of"lib1.lib" lib.d
dmd -g -debug -X main.d lib1.lib
main
==================================== 

"Lloyd Dupont" <ld-REMOVE galador.net> writes:

In plain English what I am trying to do:

I'm testing that the property can be set.
I.e.
class Foo
{
 property public Foo Subfoo() {}

 property public Foo Subfoo2() {}
 property public void Subfoo2(Foo f) {}
}

in the above class Subfoo can't be set, Subfoo2 can.
I'm testing it with
Foo f,
__traits(compile, f.Suboo = Foo.init)
__traits(compile, f.Suboo2 = Foo.init)


because the field name are going to be a parameter there is a bit of 
convolution and mixin and template.
anyway...

Apparently I just recieved a response "it's not a bug" (it's a feature) 
because
-------
 TemplateInstantances are always performed in the scope of where the 
 TemplateDeclaration is declared, with the addition of the template 
 parameters being declared as aliases for their deduced types.



I don't even understand how the answer relate to my problem, nor how to 
solve it!
Can any one explain to  (in plain understandable English) why is it a 
feature, and, most importantly, how to work around it!?!?

"Lloyd Dupont" <ld-REMOVE galador.net> writes:

Apparently it's not a bug, it's feature (I can't begin to fathom why)

At any rate, by replacing
writeln(mixin( "__traits(compiles, t." ~memberName ~" = (" 
~typeof(__traits(getMember, T, memberName)).stringof  ~").init)" ));


with
writeln(mixin( "__traits(compiles, t." ~memberName ~" = (typeof(t." 
~memberName ~")).init)" ));


it works as expected!