Re: UDA and ReturnType!(__traits...) doesn't work
On Sunday, 3 May 2015 at 17:22:00 UTC, filcuc wrote:
Hi all,
i'm working in the generation of the code but i'm failing in
extracting a function return type when invoking the
ReturnType!(T) type trait and mixing it with
__traits(getMember) function.
Can anyone help me? or explaining what is happenning?
i've created a gist here:
https://gist.github.com/filcuc/14c3a6cac89beb69cccd
The error message is the following:
main.d-mixin-58(58): Error: template instance
main.Person.ReturnType!(name) does not match template
declaration ReturnType(func...) if (func.length == 1
isCallable!func)
main.d-mixin-58(58): Error: template instance
std.traits.ReturnType!(Monitor) does not match template
declaration ReturnType(func...) if (func.length == 1
isCallable!func)
main.d(73): Error: template instance main.IterateUDA!(Person)
error instantiating
Try adding the following around your 'string returnType = ...'
code:
static if(isSomeFunction!(__traits(get member, T, member))
{
...
}
The problem is that you're looping over all the fields in T,
including the data members which obviously don't have a return
type. I guess ReturnType should probably use a static assert to
give a better error message.
Re: UDA and ReturnType!(__traits...) doesn't work
On Sun, 03 May 2015 17:21:58 +, filcuc wrote:
Hi all,
i'm working in the generation of the code but i'm failing in extracting
a function return type when invoking the ReturnType!(T) type trait and
mixing it with __traits(getMember) function.
Can anyone help me? or explaining what is happenning?
i've created a gist here:
https://gist.github.com/filcuc/14c3a6cac89beb69cccd
The error message is the following:
main.d-mixin-58(58): Error: template instance
main.Person.ReturnType!(name) does not match template declaration
ReturnType(func...) if (func.length == 1 isCallable!func)
main.d-mixin-58(58): Error: template instance
std.traits.ReturnType!(Monitor) does not match template declaration
ReturnType(func...) if (func.length == 1 isCallable!func)
main.d(73): Error: template instance main.IterateUDA!(Person) error
instantiating
the thing is that you mixed CTFE and runtime code in a weird way. ;-)
the following works:
void IterateUDA(T)() {
import std.typetuple : staticIndexOf;
foreach (member; __traits(allMembers, T)) {
// Check that the given member is a function
static if (is(typeof(__traits(getMember, T, member {
bool isFunction = __traits(isVirtualFunction, __traits(getMember,
T, member));
if (!isFunction) continue;
// Retrieve the UDA
enum attributes = __traits(getAttributes, __traits(getMember, T,
member));
// Extract the Function Return Type and Arguments if `Slot()` is
found
static if (staticIndexOf!(Slot(), attributes) = 0) {
enum returnType = ReturnType!(__traits(getMember, T,
member)).stringof;
import std.stdio;
writeln(returnType);
}
}
}
}
yet i think you need to read more about CTFE and metaprogramming, to
avoid mixing different code.
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Description: PGP signature
Re: UDA and ReturnType!(__traits...) doesn't work
On Sun, 03 May 2015 18:02:37 +, filcuc wrote: Yep sorry, i'm still learning :) i'm not blaming you at all. what i mean i that i'm bad at explanations, so you'd better read one of the D books to better understand my cryptic don't do that, do this comments. ;-) signature.asc Description: PGP signature
Re: UDA and ReturnType!(__traits...) doesn't work
On Sunday, 3 May 2015 at 17:48:55 UTC, ketmar wrote:
On Sun, 03 May 2015 17:21:58 +, filcuc wrote:
Hi all,
i'm working in the generation of the code but i'm failing in
extracting
a function return type when invoking the ReturnType!(T) type
trait and
mixing it with __traits(getMember) function.
Can anyone help me? or explaining what is happenning?
i've created a gist here:
https://gist.github.com/filcuc/14c3a6cac89beb69cccd
The error message is the following:
main.d-mixin-58(58): Error: template instance
main.Person.ReturnType!(name) does not match template
declaration
ReturnType(func...) if (func.length == 1 isCallable!func)
main.d-mixin-58(58): Error: template instance
std.traits.ReturnType!(Monitor) does not match template
declaration
ReturnType(func...) if (func.length == 1 isCallable!func)
main.d(73): Error: template instance main.IterateUDA!(Person)
error
instantiating
the thing is that you mixed CTFE and runtime code in a weird
way. ;-)
the following works:
void IterateUDA(T)() {
import std.typetuple : staticIndexOf;
foreach (member; __traits(allMembers, T)) {
// Check that the given member is a function
static if (is(typeof(__traits(getMember, T, member {
bool isFunction = __traits(isVirtualFunction,
__traits(getMember,
T, member));
if (!isFunction) continue;
// Retrieve the UDA
enum attributes = __traits(getAttributes,
__traits(getMember, T,
member));
// Extract the Function Return Type and Arguments if
`Slot()` is
found
static if (staticIndexOf!(Slot(), attributes) = 0) {
enum returnType = ReturnType!(__traits(getMember, T,
member)).stringof;
import std.stdio;
writeln(returnType);
}
}
}
}
yet i think you need to read more about CTFE and
metaprogramming, to
avoid mixing different code.
Yep sorry,
i'm still learning :)
However thank you all for your help and the quick answer.
As you suggested wrapping the body with the static if solved the
problem.
I've updated the gist
https://gist.github.com/filcuc/14c3a6cac89beb69cccd
Thanks!
UDA and ReturnType!(__traits...) doesn't work
Hi all, i'm working in the generation of the code but i'm failing in extracting a function return type when invoking the ReturnType!(T) type trait and mixing it with __traits(getMember) function. Can anyone help me? or explaining what is happenning? i've created a gist here: https://gist.github.com/filcuc/14c3a6cac89beb69cccd The error message is the following: main.d-mixin-58(58): Error: template instance main.Person.ReturnType!(name) does not match template declaration ReturnType(func...) if (func.length == 1 isCallable!func) main.d-mixin-58(58): Error: template instance std.traits.ReturnType!(Monitor) does not match template declaration ReturnType(func...) if (func.length == 1 isCallable!func) main.d(73): Error: template instance main.IterateUDA!(Person) error instantiating
