Getting only the data members of a type

[Artur Skawina]

On 04/01/12 08:18, Ali Çehreli wrote:
> On 03/31/2012 09:09 PM, Artur Skawina wrote:
>> On 03/31/12 21:09, Ali Çehreli wrote:
>>> How can I determine just the data members of a struct or class, excluding the member functions? isCallable() comes short as member variable that have opCall() defined are also callable:
>> [...]
>>> Wait! I found a solution before sending this message. :P isIntegral() works:
>>>
>>>          if (isIntegral!(typeof(mixin("S." ~ member)))) {
>>>
>>> Now the output is:
>>>
>>>      i is a member function
>>>      m is a member variable<-- good but dubious
>>>    foo is a member variable
>> [...]
>>
>> Don't forget about templates (appear as members too, but don't have a type).
> 
> I see. We can't even use isCallable or isIntegral with a template member. Assuming S has this member function template:
> 
>     void bar(T)()
>     {}
> 
> Then we get the following error:
> 
> /usr/include/d/dmd/phobos/std/traits.d(3223): Error: (S).bar(T) has no value
> 
> I don't know a way of saying "if a template".
      
eg:
   static if (!__traits(compiles, &__traits(getMember, obj, name)))
or just
   static if (!is(typeof(member))) 

>> This will print all fields of struct/class S:
>>
>>     enum s = cast(S*)null;
>>     foreach (i, m; s.tupleof) {
>>        enum name = S.tupleof[i].stringof[4..$];
>>        alias typeof(m) type;
>>        writef("(%s) %s\n", type.stringof, name);
>>     }
>>
>> Real Programmers don't use std.traits. ;)
>>
>> artur
> 
> Your method works but needing to iterate on a struct variable by s.tupleof and having to use the struct type as S.tupleof in the loop body is strange.

That's because the compiler won't accept "foreach (i, t; S.tupleof)" and 
"*.tupleof[i].stringof" is necessary to get the original name. This would
have worked too:

      enum name = *s.tupleof[i].stringof[4..$];

but obfuscates the code more and looks like dereferencing a null pointer.

artur