On Sunday, 11 August 2019 at 15:27:54 UTC, Sjoerd Nijboer wrote:
The following snippet doesn't compile
I am trying to reflect on a class and only do an operation with
all member functions of a class.
But I can't seem to use a filter to only get the member
functions out of a type T.
I understand that there are two errors in my snippet.
1) It cannot mixin a `name` because it is a variable from the
lambda that `filter()` is using.
2) members.filter!(name => !ctorAndDtor.canFind(name)) does not
filter on symbols defined in ctorAndDtor
How can I fix these problems and return all member functions
whitout ctor and dtor of a type T?
This is classic D mix of compile-time and compile-time (no typo).
I suggest reading H.S. Teoh's text on the topic:
https://wiki.dlang.org/User:Quickfur/Compile-time_vs._compile-time
Now, as for what can actually be done: you should probably use
std.meta.Filter (https://dlang.org/library/std/meta/filter.html)
to filter the members list. This will require you to define a
template to operate on each element. Something like this:
import std.meta : Filter;
import std.traits : isFunction;
import std.algorithm.searching : canFind;
enum isNonspecialMemberFunction(string name) =
!ctorAndDtor.canFind(name) &&
isFunction!(__traits(getMember, T, name));
enum memberFunctions = Filter!(isNonspecialMemberFunction,
__traits(derivedMembers, T));
Filter operates on AliasSeqs, not arrays. That's why I restated
the __traits(derivedMembers, T) part, but this could just as
easily be done by changing this line:
enum members = [__traits(derivedMembers, T)];
to:
alias members = __traits(derivedMembers, T);
--
Simen
