static code generation

[r_m_r]

On 12/21/2012 07:18 AM, js.mdnq wrote:
> struct S_A { int x; int y; void func(); void funcA(); }
> struct S_B { int x; int z; void func(); void funcB(); }
>
> then GenUnion(S_A, S_B) will produce a struct like
> S_AB
> {
>     int x;
>     int y;
       int z; //did u miss this? ;)
>     void func();
>     void funcA();
>     void funcB();
> }

check this: http://pastebin.com/BQW7DtSD

struct S_A { int x; int y; void func() { x = 2*x; }; void funcA() { }; }
struct S_B { int x; int z; void func() { x = 3*x; }; void funcB() { }; }

void main()
{
     import std.stdio: writeln;

     mixin (Gen!("S_AB", S_A, S_B));
     pragma(msg, __traits(allMembers, S_AB));
     //prints: tuple("_s0","_s1","x","y","func","funcA","z","funcB")

     S_AB s_ab;
     s_ab.x = 10;
     s_ab.func();
     assert(s_ab.x == 20);
}

BTW what you are trying to achieve with your GenUnion(S_A, S_B) may 
require functionality currently missing in D (as you've already 
mentioned). For example, I can generate a struct with the fields from 
the two structs S_A and S_B like so:

struct S_AB
{
     int x;
     int y;
     int z;
     void func() { } ; //note the empty function body
     void funcA() { } ;
     void funcB() { };
}

but it will be useless since AFAIK I cannot get a stringof S_A.func()'s 
body at compile time.

One alternative as I've shown is to generate a struct with hidden fields 
and properties (until 'multiple alias this' functionality gets 
implemented) which will atleast behave like your GenUnion(S_A, S_B) 
struct (from a user perspective).

BTW if you find any interesting alternative, please consider adding it 
to the dwiki - http://wiki.dlang.org/ (for e.g.: 
http://wiki.dlang.org/Combining_Structs)

regards,
r_m_r