• Sjoerd Nijboer (45/45) Aug 11 2019 The following snippet doesn't compile
• Simen =?UTF-8?B?S2rDpnLDpXM=?= (25/37) Aug 11 2019 This is classic D mix of compile-time and compile-time (no typo).
• Sjoerd Nijboer (2/20) Aug 11 2019 Works beautiful, thank you very much!

Sjoerd Nijboer <dlang sjoerdnijboer.com> writes:

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?

Code snippet:

void main()
{
     GetFunctionMembers!Foo();
}

void GetFunctionMembers(T)()
{
     enum members = [__traits(derivedMembers, T)];
     pragma(msg, "Functions: " ~ members.stringof);

     enum ctorAndDtor = ["this", "__ctor", "__dtor"];
     enum memberFunctions = members.filter!(name => 
!ctorAndDtor.canFind(name)
                 && mixin("isFunction!(T." ~ name ~ ")"))();

     pragma(msg, memberFunctions);
}

class Foo
{
     bool myBool;
     int k;

     this()
     {
     }

     ~this()
     {
     }

     void bar(int k)
     {
         this.k = k;
     }

     void qux()
     {
     }
}

Simen =?UTF-8?B?S2rDpnLDpXM=?= <simen.kjaras gmail.com> writes:

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

Sjoerd Nijboer <dlang sjoerdnijboer.com> writes:

On Sunday, 11 August 2019 at 16:32:20 UTC, Simen Kjærås wrote:
 [...] 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

Works beautiful, thank you very much!