Re: mixed in struct constructor is ignored when another (non mixed in) constructor is specified
On Monday, 26 February 2018 at 14:42:58 UTC, Adam D. Ruppe wrote: On Monday, 26 February 2018 at 14:38:22 UTC, ParticlePeter wrote: This cool, I didn't know that we can name mixins when instantiating but also never taught that there could be any purpose for naming. Works, thanks. oh yes, there's a lot of cool things with mixin. You might want to skim my tip of the week index: http://arsdnet.net/this-week-in-d/totw-index.html and see if more jump out at you. template mixins have behavior that look stupid until you understand why - then it gets pretty nice. Like the naming and overloading rules allow selective overriding and integration once you know how. Ok and that is an awesome link as well, I wished having this on several occasions. By the way, I also remembered reading your tip already once ... yeah, while reading it again. Anyway, thanks.
Re: mixed in struct constructor is ignored when another (non mixed in) constructor is specified
On Monday, 26 February 2018 at 14:38:22 UTC, ParticlePeter wrote: This cool, I didn't know that we can name mixins when instantiating but also never taught that there could be any purpose for naming. Works, thanks. oh yes, there's a lot of cool things with mixin. You might want to skim my tip of the week index: http://arsdnet.net/this-week-in-d/totw-index.html and see if more jump out at you. template mixins have behavior that look stupid until you understand why - then it gets pretty nice. Like the naming and overloading rules allow selective overriding and integration once you know how.
Re: mixed in struct constructor is ignored when another (non mixed in) constructor is specified
On Monday, 26 February 2018 at 14:02:56 UTC, Adam D. Ruppe wrote: On Monday, 26 February 2018 at 12:30:24 UTC, ParticlePeter wrote: Is this expected behavior? yes sort of, but there are bugs associated with it too... I wrote about this in the "Tip of the Week" section here before http://arsdnet.net/this-week-in-d/2016-feb-07.html there's a workaround there and a bit more explanation of weirdness. This cool, I didn't know that we can name mixins when instantiating but also never taught that there could be any purpose for naming. Works, thanks.
Re: mixed in struct constructor is ignored when another (non mixed in) constructor is specified
On Monday, 26 February 2018 at 12:30:24 UTC, ParticlePeter wrote: Is this expected behavior? yes sort of, but there are bugs associated with it too... I wrote about this in the "Tip of the Week" section here before http://arsdnet.net/this-week-in-d/2016-feb-07.html there's a workaround there and a bit more explanation of weirdness.
Re: mixed in struct constructor is ignored when another (non mixed in) constructor is specified
On Monday, 26 February 2018 at 13:09:40 UTC, ParticlePeter wrote:
Thanks for clarification, unfortunately your suggestion doesn't
work.
Since when is alias this = something; supposed to work?
alias Common.this this; doesn't work as well and following also
not:
struct Baz {
Foo foo;
alias foo this;
this( int m, int n ) { m_member = m * n; }
}
auto baz = Baz(1); // Error, same as above
Not sure if I do require an enhancement, I just stumbled on
that and was wondering.
The workaround for now is to define your other constructor in
another mixin template:
struct Bar {
mixin Common;
mixin template Common2() {this( int m, float n ) { m_member =
cast(int)(m * n); } };
mixin Common2;
}
It's not exactly pretty, but it works.
An issue has already been filed for this:
https://issues.dlang.org/show_bug.cgi?id=17055.
--
Simen
Re: mixed in struct constructor is ignored when another (non mixed in) constructor is specified
On Monday, 26 February 2018 at 12:47:48 UTC, Jonathan M Davis
wrote:
On Monday, February 26, 2018 12:30:24 ParticlePeter via
Digitalmars-d-learn wrote:
mixin template Common() {
private int m_member;
this( int m ) { m_member = m; }
}
struct Foo {
mixin Common;
}
struct Bar {
mixin Common;
this( int m, float n ) { m_member = m * n; }
}
auto foo = Foo(1); // ok
auto b_1 = Bar( 1, 2 ); // ok
auto b_2 = Bar( 3 ); // Error: constructor main.Bar.this
(int
m, int n) is not callable using argument types (int)
Is this expected behavior?
Yes. Stuff that's mixed in is treated as having a different
scope than other mixins or stuff that wasn't mixed in. To quote
towards the bottom of here:
https://dlang.org/spec/template-mixin.html
"Alias declarations can be used to overload together functions
declared in different mixins"
It gives an example of
mixin Foo!() F;
mixin Bar!() B;
alias func = F.func;
alias func = B.func;
I don't know if you can do the same thing with constructors or
not, though alias this statements don't allow the = syntax. So,
maybe that won't conflict, and it will work to do something like
alias this = Common.this;
If that doesn't work, then it seems like a good enhancement
request.
- Jonathan M Davis
Thanks for clarification, unfortunately your suggestion doesn't
work.
Since when is alias this = something; supposed to work?
alias Common.this this; doesn't work as well and following also
not:
struct Baz {
Foo foo;
alias foo this;
this( int m, int n ) { m_member = m * n; }
}
auto baz = Baz(1); // Error, same as above
Not sure if I do require an enhancement, I just stumbled on that
and was wondering.
Re: mixed in struct constructor is ignored when another (non mixed in) constructor is specified
On Monday, February 26, 2018 12:30:24 ParticlePeter via Digitalmars-d-learn
wrote:
> mixin template Common() {
>private int m_member;
>this( int m ) { m_member = m; }
> }
>
> struct Foo {
>mixin Common;
> }
>
> struct Bar {
>mixin Common;
>this( int m, float n ) { m_member = m * n; }
> }
>
>
> auto foo = Foo(1); // ok
> auto b_1 = Bar( 1, 2 ); // ok
> auto b_2 = Bar( 3 ); // Error: constructor main.Bar.this (int
> m, int n) is not callable using argument types (int)
>
> Is this expected behavior?
Yes. Stuff that's mixed in is treated as having a different scope than other
mixins or stuff that wasn't mixed in. To quote towards the bottom of here:
https://dlang.org/spec/template-mixin.html
"Alias declarations can be used to overload together functions declared in
different mixins"
It gives an example of
mixin Foo!() F;
mixin Bar!() B;
alias func = F.func;
alias func = B.func;
I don't know if you can do the same thing with constructors or not, though
alias this statements don't allow the = syntax. So, maybe that won't
conflict, and it will work to do something like
alias this = Common.this;
If that doesn't work, then it seems like a good enhancement request.
- Jonathan M Davis
mixed in struct constructor is ignored when another (non mixed in) constructor is specified
mixin template Common() {
private int m_member;
this( int m ) { m_member = m; }
}
struct Foo {
mixin Common;
}
struct Bar {
mixin Common;
this( int m, float n ) { m_member = m * n; }
}
auto foo = Foo(1); // ok
auto b_1 = Bar( 1, 2 ); // ok
auto b_2 = Bar( 3 ); // Error: constructor main.Bar.this (int
m, int n) is not callable using argument types (int)
Is this expected behavior?
