digitalmars.D.learn - alias c=mixin(expr); disallowed, why?
- Timothee Cour (9/9) Jun 22 2013 Is there a reason the language spec disallows this?
- Timon Gehr (2/11) Jun 22 2013 No, it is arbitrary.
- Timothee Cour (5/18) Jun 22 2013 that's what i thought!
- Timon Gehr (4/22) Jun 22 2013 It surely could be fixed if you want to spend the time hacking on DMD.
- Timothee Cour (3/39) Jun 22 2013 they're restricted to declarations. I don't see the need for such
- Jacob Carlborg (6/7) Jun 23 2013 I think the spec says you can only mixin whole expression. But for some
- Timon Gehr (8/14) Jun 23 2013 That only means you cannot do things like eg:
- Jacob Carlborg (5/6) Jun 23 2013 @(3) int a;
Is there a reason the language spec disallows this?
----
void main(){
auto a=mixin("1");//OK
alias b=a;//OK
mixin("alias c=a;");//OK
// alias c=mixin("a");//NG : Error: basic type expected, not mixin
}
----
Jun 22 2013
On 06/22/2013 09:52 PM, Timothee Cour wrote:
Is there a reason the language spec disallows this?
----
void main(){
auto a=mixin("1");//OK
alias b=a;//OK
mixin("alias c=a;");//OK
// alias c=mixin("a");//NG : Error: basic type expected, not mixin
}
----
No, it is arbitrary.
Jun 22 2013
On Sat, Jun 22, 2013 at 2:47 PM, Timon Gehr <timon.gehr gmx.ch> wrote:On 06/22/2013 09:52 PM, Timothee Cour wrote:that's what i thought! same with template mixin's being restricated. ... can we fix it? it makes for cleaner code.Is there a reason the language spec disallows this? ---- void main(){ auto a=mixin("1");//OK alias b=a;//OK mixin("alias c=a;");//OK // alias c=mixin("a");//NG : Error: basic type expected, not mixin } ----No, it is arbitrary.
Jun 22 2013
On 06/22/2013 11:51 PM, Timothee Cour wrote:On Sat, Jun 22, 2013 at 2:47 PM, Timon Gehr <timon.gehr gmx.ch <mailto:timon.gehr gmx.ch>> wrote: On 06/22/2013 09:52 PM, Timothee Cour wrote: Is there a reason the language spec disallows this? ---- void main(){ auto a=mixin("1");//OK alias b=a;//OK mixin("alias c=a;");//OK // alias c=mixin("a");//NG : Error: basic type expected, not mixin } ---- No, it is arbitrary. that's what i thought! same with template mixin's being restricated.?... can we fix it? it makes for cleaner code.It surely could be fixed if you want to spend the time hacking on DMD. I think the grammar is somewhat poorly designed in general.
Jun 22 2013
Timothee Cour <thelastmammoth gmail.com> On Sat, Jun 22, 2013 at 2:55 PM, Timon Gehr <timon.gehr gmx.ch> wrote:On 06/22/2013 11:51 PM, Timothee Cour wrote:they're restricted to declarations. I don't see the need for such restriction.On Sat, Jun 22, 2013 at 2:47 PM, Timon Gehr <timon.gehr gmx.ch <mailto:timon.gehr gmx.ch>> wrote: On 06/22/2013 09:52 PM, Timothee Cour wrote: Is there a reason the language spec disallows this? ---- void main(){ auto a=mixin("1");//OK alias b=a;//OK mixin("alias c=a;");//OK // alias c=mixin("a");//NG : Error: basic type expected, not mixin } ---- No, it is arbitrary. that's what i thought! same with template mixin's being restricated.?... can we fix it?it makes for cleaner code.It surely could be fixed if you want to spend the time hacking on DMD. I think the grammar is somewhat poorly designed in general.
Jun 22 2013
On 2013-06-22 23:47, Timon Gehr wrote:No, it is arbitrary.I think the spec says you can only mixin whole expression. But for some reason you can use a mixin in a __traits expression without having the whole expression in a mixin. -- /Jacob Carlborg
Jun 23 2013
On 06/23/2013 11:32 AM, Jacob Carlborg wrote:On 2013-06-22 23:47, Timon Gehr wrote:That only means you cannot do things like eg: mixin("a*"); mixin("b"); but instead you need to do: mixin("a*b"); such that the string content forms a valid expression according to the grammar.No, it is arbitrary.I think the spec says you can only mixin whole expression.But for some reason you can use a mixin in a __traits expression without having the whole expression in a mixin.Example?
Jun 23 2013
On 2013-06-23 13:27, Timon Gehr wrote:Example?(3) int a; alias Tuple!(__traits(getAttributes, mixin("a"))) attrs; -- /Jacob Carlborg
Jun 23 2013