getting member functions of a struct and Error: identifier expected following ., not this

[aliak via Digitalmars-d-learn]

Hi, I'm trying to get a list of only member functions of a 
struct. I've found that if you do not declare a struct as static 
inside a scope, then there's a hidden "this" member as part of 
the struct. Can someone explain the logic there?


Also am I going about this correctly?

template MemberFunctions(T) {
import std.traits: isFunction;
auto MemberFunctions() {
string[] memberFunctions;
foreach (member; __traits(allMembers, T)) {

// NOTE: This static if is here is because of that 
hidden "this" member

//
// if I do not do this then I get:
//   Error: identifier expected following ., not this

static if (is(typeof(mixin("T." ~ member)) F))
if (isFunction!F) {
memberFunctions ~= member;
}
}
return memberFunctions;
}
}

unittest {
// works for static and non static.
/* static */ struct A {
void opCall() {}
void g() {}
}

/* static */ struct B {
int m;
A a;
alias a this;
void f() {}
}

static assert(MemberFunctions!B == ["f"]);
}

Cheers

Re: getting member functions of a struct and Error: identifier expected following ., not this

[aliak via Digitalmars-d-learn]

On Tuesday, 23 January 2018 at 00:00:38 UTC, aliak wrote:

Hi, I'm trying to get a list of only member functions of a [...]
Cheers


And a follow up question: should I be using static foreach in 
there instead of a normal foreach? i.e.


foreach (member; __traits(allMembers, T)) {{
// same code
}}

And why if yes

Thanks again!

Re: getting member functions of a struct and Error: identifier expected following ., not this

[thedeemon via Digitalmars-d-learn]

On Tuesday, 23 January 2018 at 00:00:38 UTC, aliak wrote:
Hi, I'm trying to get a list of only member functions of a 
struct. I've found that if you do not declare a struct as 
static inside a scope, then there's a hidden "this" member as 
part of the struct. Can someone explain the logic there?


The struct defined inside a scope can mention variables defined 
in that scope (e.g. use them in its methods), so it needs a 
pointer to the place where those closed variables live. That's 
the main difference between such struct and a static one that 
cannot use those scope vars. I guess you're seeing that pointer 
as additional member.



As for static foreach, when you write a simple foreach over some 
compile-time tuple (like in this case), it's unrolled at compile 
time similarly to "static foreach", the main difference is 
whether it creates a sub-scope for the loop body or not. 
"foreach" creates one, "static foreach" doesn't.

Re: getting member functions of a struct and Error: identifier expected following ., not this

[aliak via Digitalmars-d-learn]

On Wednesday, 24 January 2018 at 07:55:01 UTC, thedeemon wrote:

On Tuesday, 23 January 2018 at 00:00:38 UTC, aliak wrote:

[...]


The struct defined inside a scope can mention variables defined 
in that scope (e.g. use them in its methods), so it needs a 
pointer to the place where those closed variables live. That's 
the main difference between such struct and a static one that 
cannot use those scope vars. I guess you're seeing that pointer 
as additional member.



As for static foreach, when you write a simple foreach over 
some compile-time tuple (like in this case), it's unrolled at 
compile time similarly to "static foreach", the main difference 
is whether it creates a sub-scope for the loop body or not. 
"foreach" creates one, "static foreach" doesn't.


Ah makes sense. Thanks!