Re: How do you find the struct types in a module? - getting Error: unknown

[Steven Schveighoffer via Digitalmars-d-learn]

On 2/13/20 9:47 AM, aliak wrote:
Hi,
I'm trying to get a typed list of structs in my current module that 
matches certain criteria. Something like:

module mod;

struct X {}
struct Y {}

alias allTypes = ListOfTypes!mod;

But I'm having a bit of trouble. I have this so far:

template ListOfTypes(alias T) {
     import std.meta;
     enum isStruct(string m) = is(mixin(m) == struct);
     enum types = Filter!(isStruct, __traits(allMembers, T));
     alias toType(string m) = mixin(m);
     alias all = staticMap!(toType, types);
     alias CommandGroupsOf = all;
}

pragma(msg, ListOfTypes!mod);

But that causes an error I've never seen before:

Error: unknown, please file report on issues.dlang.org
onlineapp.d(30,1):        while evaluating `pragma(msg, 
CommandGroupsOf!(mod))`


Any workarounds or maybe insight in to the error?



Not sure about your error, but here is a working version (don't use 
mixins, use __traits(getMember)):

import std.meta;
template ListOfStructs(alias mod)
{
    enum isStruct(string m) = is(__traits(getMember, mod, m) == struct);
    alias getMember(string m) = __traits(getMember, mod, m);
    alias ListOfStructs = staticMap!(getMember, Filter!(isStruct, 
__traits(allMembers, mod)));
}

-Steve