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digitalmars.D.learn - Idiomatic way to check for UDA?

reply "Tofu Ninja" <emmons0 purdue.edu> writes:
Whats the idiomatic way to check if an identifier has a specific 
UDA attached to it.

Also what should I use to define a UDA that doesn't need to carry 
any data? Just an empty template? Or does something else make 
more sense?
Jun 06 2015
parent reply ketmar <ketmar ketmar.no-ip.org> writes:
On Sun, 07 Jun 2015 05:32:46 +0000, Tofu Ninja wrote:


 Whats the idiomatic way to check if an identifier has a specific UDA
 attached to it.
=20
 Also what should I use to define a UDA that doesn't need to carry any
 data? Just an empty template? Or does something else make more sense?


there is `std.traits.hasUDA` added to phobos recently. but until official=20
release you have to write your own `hasUDA`. alas.

as for defining UDA without data, you can use this trick:

  enum MyUDA;
   MyUDA int i;

as it doesn't really need to be semantically analyzed, this forward=20
declaration can work just fine.=
Jun 06 2015
parent reply "Marc =?UTF-8?B?U2Now7x0eiI=?= <schuetzm gmx.net> writes:
On Sunday, 7 June 2015 at 06:20:55 UTC, ketmar wrote:

 On Sun, 07 Jun 2015 05:32:46 +0000, Tofu Ninja wrote:


 Whats the idiomatic way to check if an identifier has a 
 specific UDA
 attached to it.
 
 Also what should I use to define a UDA that doesn't need to 
 carry any
 data? Just an empty template? Or does something else make more 
 sense?


 there is `std.traits.hasUDA` added to phobos recently.


Service:
https://github.com/D-Programming-Language/phobos/pull/3356
https://github.com/D-Programming-Language/phobos/pull/3363
Jun 07 2015
parent ketmar <ketmar ketmar.no-ip.org> writes:
On Sun, 07 Jun 2015 11:37:29 +0000, Marc Sch=C3=BCtz wrote:


 On Sunday, 7 June 2015 at 06:20:55 UTC, ketmar wrote:

 On Sun, 07 Jun 2015 05:32:46 +0000, Tofu Ninja wrote:


 Whats the idiomatic way to check if an identifier has a specific UDA
 attached to it.
=20
 Also what should I use to define a UDA that doesn't need to carry any
 data? Just an empty template? Or does something else make more sense?


 there is `std.traits.hasUDA` added to phobos recently.


=20
 Service: https://github.com/D-Programming-Language/phobos/pull/3356
 https://github.com/D-Programming-Language/phobos/pull/3363


thank you, i should provide the links from the start, so OP can copypaste=20
the code.=
Jun 07 2015