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digitalmars.D.learn - delegate with optional parameters

reply Inquie <Inquie data.com> writes:
is it possible to create a delegate that takes an optional number 
of parameters and/or return type?

T delegate(S...)(S) special_delegate;

I guess this is impossible?
Apr 02
parent reply Basile B. <b2.temp gmx.com> writes:
On Sunday, 2 April 2017 at 19:24:14 UTC, Inquie wrote:
 is it possible to create a delegate that takes an optional 
 number of parameters and/or return type?

 T delegate(S...)(S) special_delegate;

 I guess this is impossible?
alias Dg(Return, Params...) = Return delegate(Params); Dg!(int,float, string) myDg;
Apr 02
parent reply Inquie <Inquie data.com> writes:
On Sunday, 2 April 2017 at 20:02:56 UTC, Basile B. wrote:
 On Sunday, 2 April 2017 at 19:24:14 UTC, Inquie wrote:
 is it possible to create a delegate that takes an optional 
 number of parameters and/or return type?

 T delegate(S...)(S) special_delegate;

 I guess this is impossible?
alias Dg(Return, Params...) = Return delegate(Params); Dg!(int,float, string) myDg;
What I mean is that I want to be able to overload delegates like one can do with normal members.
Apr 02
parent reply Basile B. <b2.temp gmx.com> writes:
On Sunday, 2 April 2017 at 20:48:09 UTC, Inquie wrote:
 On Sunday, 2 April 2017 at 20:02:56 UTC, Basile B. wrote:
 On Sunday, 2 April 2017 at 19:24:14 UTC, Inquie wrote:
 is it possible to create a delegate that takes an optional 
 number of parameters and/or return type?

 T delegate(S...)(S) special_delegate;

 I guess this is impossible?
alias Dg(Return, Params...) = Return delegate(Params); Dg!(int,float, string) myDg;
What I mean is that I want to be able to overload delegates like one can do with normal members.
Show a usage, someone certainly propose a pattern that does the job.
Apr 02
parent reply Inquie <Inquie data.com> writes:
On Sunday, 2 April 2017 at 21:47:55 UTC, Basile B. wrote:
 On Sunday, 2 April 2017 at 20:48:09 UTC, Inquie wrote:
 On Sunday, 2 April 2017 at 20:02:56 UTC, Basile B. wrote:
 On Sunday, 2 April 2017 at 19:24:14 UTC, Inquie wrote:
 is it possible to create a delegate that takes an optional 
 number of parameters and/or return type?

 T delegate(S...)(S) special_delegate;

 I guess this is impossible?
alias Dg(Return, Params...) = Return delegate(Params); Dg!(int,float, string) myDg;
What I mean is that I want to be able to overload delegates like one can do with normal members.
Show a usage, someone certainly propose a pattern that does the job.
int delegate() f; void delegate(int) f; These are effectively overload methods, but my guess is that D won't support it like overloads. e.g., int f(); void f(int);
Apr 02
parent reply =?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:
On 04/02/2017 03:24 PM, Inquie wrote:

 Show a usage, someone certainly propose a pattern that does the job.
int delegate() f; void delegate(int) f;
That won't work because both of those are variables and variables don't have overloading.
 These are effectively overload methods, but my guess is that D won't
 support it like overloads.
 e.g.,

 int f();
 void f(int);
Yep, both 'f' are functions there. I'm having difficulty understanding your actual need as well. :/ A guess: It is possible to determine delegate parameter list at compile time like std.concurrency.receive does. Ali
Apr 02
parent reply Inquie <Inquie data.com> writes:
On Monday, 3 April 2017 at 03:08:22 UTC, Ali Çehreli wrote:
 On 04/02/2017 03:24 PM, Inquie wrote:

 Show a usage, someone certainly propose a pattern that does
the job.
 int delegate() f;
 void delegate(int) f;
That won't work because both of those are variables and variables don't have overloading.
 These are effectively overload methods, but my guess is that
D won't
 support it like overloads.
 e.g.,

 int f();
 void f(int);
Yep, both 'f' are functions there. I'm having difficulty understanding your actual need as well. :/ A guess: It is possible to determine delegate parameter list at compile time like std.concurrency.receive does. Ali
Yes, but they are really not any different. They only look different. A field can be a function just like a method because they look exactly the same except on is in a vtable and the other is in the fields memory. But both point functions. The only difference is that we can't write to the vtable to overwrite a value easily but we can to a delegate(no hackery). So, it would be nice to be able to overload them. Effectively we can extend the vtable out in to the fields. (it would require a bit of work to make it work identical to a class, but it could, the outside world would know no difference). If one wants: It essentially allows for methods to be modifiable at run time(something that classes can't do without unsafely hacking the vtable) and that is exactly why I have used it, but overloading causes a problem because only the name collides yet it works with the methods case but not the field delegates(a field delegate is essentially a method, is the point(for functional usage)).
Apr 02
parent Rene Zwanenburg <renezwanenburg gmail.com> writes:
On Monday, 3 April 2017 at 05:00:15 UTC, Inquie wrote:
 Yes, but they are really not any different. They only look 
 different. A field can be a function just like a method because 
 they look exactly the same except on is in a vtable and the 
 other is in the fields memory. But both point functions.
It should be possible to create a wrapper struct around your 'overloads' with an opDispatch which selects the right delegate.
Apr 03