Whats the best way to get a struct/class member type?

[simendsjo]

On Mon, 02 Apr 2012 10:51:35 +0200, Simen Kjaeraas  
<simen.kjaras at gmail.com> wrote:

> On Mon, 02 Apr 2012 09:58:18 +0200, simendsjo <simendsjo at gmail.com>  
> wrote:
>
>> On Mon, 02 Apr 2012 00:04:58 +0200, Simen Kjærås  
>> <simen.kjaras at gmail.com> wrote:
>>
>>> On Sat, 31 Mar 2012 15:20:42 +0200, simendsjo <simendsjo at gmail.com>  
>>> wrote:
>>>
>>>> Seems __traits doesn't have a __traits(getMemberType, T, name).
>>>> Now I'm doing the following:
>>>> T t; // instance to use in getMember
>>>> alias typeof( __traits(getMember, t, name) ) MemberType;
>>>>
>>>> Is this the only way to get the type of a field based on the name?
>>>
>>> I'd think so, apart from tupleof, as Jacob's already mentioned.
>>>
>>> It's easily factored out, though:
>>>
>>> template getMemberType(T, string name) if  
>>> (is(typeof(__traits(getMember, T, name)))) {
>>>      alias typeof(__traits(getMember, T, name)) getMemberType;
>>> }
>>
>>
>> getMember requires an instance, not a type, so it should be
>>
>> template getMemberType(T, string name) if(__traits(hasMember, T, name) {
>>      T t;
>>      alias typeof(__traits(getMember, t, name)) getMemberType;
>> }
>
> Tested and works for me under 2.058 with just the type.

You're right - works on 2.059 trunk too..

The documentation explicitly says it shouldn't work for other than static  
members though.
http://dlang.org/traits.html#getMember