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digitalmars.D.bugs - [Issue 8441] New: function expected, not <my function>

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           Summary: function expected, not <my function>
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: normal
          Priority: P2
         Component: DMD
        AssignedTo: nobody puremagic.com
        ReportedBy: ellery-newcomer utulsa.edu



14:06:24 PDT ---
code:

mixin template T(string i) {
    auto j(string s="a", U)(U u1, U u2) {
        return 0;
    }
    auto j(int i,string s="a", W)(W u1, W u2) {
        return i;
    }

    mixin("
    class F" ~ i ~ " {
    auto j(string s=\"a\", U)(U u1, U u2) {
        return this.outer.t" ~ i ~ ".j!(s,U)(u1,u2);
    }
    auto j(int i,string s=\"a\", W)(W u1, W u2) {
        return this.outer.t" ~ i ~ ".j!(i,s,W)(u1,u2); <- dmd is giving error
for j!(...).j's type
    }
    }
    auto f"~i~"() {
        return new F"~i~"();
    }
    ");

}

class X {
    mixin T!("1") t0;
    alias t0 t1;
}
void main (){ 
    X x = new X();
    x.f1().j!(3,"a")(2.2, 3.3);
}


fireworks:

tok.d(15): Error: function expected before (), not 'this.this.j!(3,"a",double)'
tok.d(31): Error: template instance tok.X.T!("1").F1.j!(3,"a",double) error
instantiating

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jfanatiker gmx.at changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jfanatiker gmx.at



Can also reproduced with: 
https://github.com/eskimor/phobos/blob/new_signal/std/signals.d

And is currently a blocker for a full signals2 implementation.

Without it, I can only provide the FullSignal struct, which is good but does
not support easily restriction of access to emit(). So users would have to
redundantly create boilerplate code. Another option would be to use string
mixins, but the syntax would not be as nice, so I would like to stick with the
current implementation.

To summarize the problem: A mixin seems not to work with methods that are
templates themselves, resulting in strange errors like: 

std/signals.d(730): Error: no overload matches for disconnect(string
method,ClassType)

or

std/signals.d(633): Error: function expected before (), not
'a.connect!("watch")'

Tested with dmd 2.060 and current master
(7c370f71641c4408ddc9ebd5709e6e182e34ad2b).

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jfanatiker gmx.at changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |blocker


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monarchdodra gmail.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |monarchdodra gmail.com



It would appear the problem lies between a combination of mixin identifier, and
template overload:

Here is a reduced test case:
//----
mixin template T() {
   void k()(){}

   void j()(){}
   void j(int i)(){}
}
class X
{
   mixin T t0;
}
void main (){ 
   X x;
   x.k!()();    //Fine
   x.j!()();    //Fine
   x.t0.k!()(); //Fine
   x.t0.j!()(); //Derp
}
//---- 
main.d(12): Error: function expected before (), not 'x.j!()'
//-----



 Can also reproduced with: 
 https://github.com/eskimor/phobos/blob/new_signal/std/signals.d
 
 And is currently a blocker for a full signals2 implementation.


I don't know how you are affected by this, but you can workaround the problem
by avoiding the template overload ambiguity. For example, this seems to work:

//----
mixin template T(string i) {

    private {
        auto j1(string s="a", U)(U u1, U u2) {
            return j!(s, U)(u1, u2);
        }
        auto j2(int i,string s="a", W)(W u1, W u2) {
            return j!(i, s, W)(u1, u2);
        }
    }

    auto j(string s="a", U)(U u1, U u2) {
        return 0;
    }
    auto j(int i,string s="a", W)(W u1, W u2) {
        return i;
    }

    mixin("
    class F" ~ i ~ " {
    auto j(string s=\"a\", U)(U u1, U u2) {
        return this.outer.t" ~ i ~ ".j1!(s,U)(u1,u2);
    }
    auto j(int i,string s=\"a\", W)(W u1, W u2) {
        return this.outer.t" ~ i ~ ".j2!(i,s,W)(u1,u2);
    }
    }
    auto f"~i~"() {
        return new F"~i~"();
    }
    ");

}

class X {
    mixin T!("1") t0;
    alias t0 t1;
}
void main (){ 
    X x = new X();
    x.f1().j!(3,"a")(2.2, 3.3);
}
//----

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Ah, I see: So the issue is that template overloads don't work. Thanks for
investigating this!

Unfortunately it does not really help for std.signals2, because renaming the
methods to connectDirectly, connectViaDelegate, .... seems rather ugly,
although I don't think it is a good idea to alter a public API because of
workarounds. I would be fine, if it only affected private parts.

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 Ah, I see: So the issue is that template overloads don't work.


In the context of template mixins with mixinIdentifiers only. Template
overloads, as a general rule, do work.


 Thanks for
 investigating this!
 
 Unfortunately it does not really help for std.signals2, because renaming the
 methods to connectDirectly, connectViaDelegate, .... seems rather ugly,
 although I don't think it is a good idea to alter a public API because of
 workarounds. I would be fine, if it only affected private parts.


Technically, I didn't rename anything. I merelly added some extra functions to
remove the ambiguity in the context of the mixin identifier.

Yes, it is ugly, but the public interface is intact.

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 In the context of template mixins with mixinIdentifiers only. Template
 overloads, as a general rule, do work.


Yeah, I meant that. I used to think that template functions in a mixin
template don't work, but it is just overloads. Thanks for pointing this
out.


 Unfortunately it does not really help for std.signals2, because


 renaming the

 methods to connectDirectly, connectViaDelegate, .... seems rather


 ugly,

 although I don't think it is a good idea to alter a public API


 because of

 workarounds. I would be fine, if it only affected private parts.


 
 Technically, I didn't rename anything. I merelly added some extra
 functions to
 remove the ambiguity in the context of the mixin identifier.
 
 Yes, it is ugly, but the public interface is intact.


But the instantiation of a signal and the access:
mixin T!("1") t0;
alias t0 t1;
x.f1().j!(3,"a")(2.2, 3.3);

vs
mixin T!() t0;
x.t0.j!(3,"a")(2.2, 3.3);

would change, which is part of the public accessible API. If the
workaround gets removed, people would have to adopt their code, which is
kind of unacceptable for phobos.

Best regards,

Robert

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 But the instantiation of a signal and the access:
 mixin T!("1") t0;
 alias t0 t1;
 x.f1().j!(3,"a")(2.2, 3.3);
 
 vs
 mixin T!() t0;
 x.t0.j!(3,"a")(2.2, 3.3);
 
 would change, which is part of the public accessible API. If the
 workaround gets removed, people would have to adopt their code, which is
 kind of unacceptable for phobos.
 
 Best regards,
 
 Robert


I don't understand. You used to have:
mixin T!("1") t0;
alias t0 t1;
x.f1().j!(3,"a")(2.2, 3.3);

And I proposed something that worked with
mixin T!("1") t0;
alias t0 t1;
x.f1().j!(3,"a")(2.2, 3.3);

Nothing changed. Where did:
mixin T!() t0;
x.t0.j!(3,"a")(2.2, 3.3);

Come from?

All you should need is a private "man in the middle"...

Well, I don't have your end code, so I don't know how acceptable that is
anyways. Good luck :)

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Ha! Sorry :-) I completely forgot about the example of Ellery Newcomer (And I
wondered already how you made up such an elaborate solution, from such a simple
problem ;-) ).
The code I am concerned with is:
https://github.com/eskimor/phobos/blob/new_signal/std/signals.d

The template mixin code in particular:
mixin template Signal(Args...)
{
    private final void emit( Args args )
    {
        full.emit(args);
    }
    final void connect(string method, ClassType)(ClassType obj) if(is(ClassType
== class) && __traits(compiles, {void delegate(Args)
dg=mixin("&obj."~method);}))
    {
        full.connect!method(obj);
    }
    final void connect(ClassType)(ClassType obj, void delegate(ClassType obj,
Args) dg) if(is(ClassType == class))
    {
        full.connect(obj, dg);
    }
    final void strongConnect(void delegate(Args) dg)
    {
        full.strongConnect(dg);
    }
    final void disconnect(string method, ClassType)(ClassType obj)
if(is(ClassType == class) && __traits(compiles, {void delegate(Args)
dg=mixin("&obj."~method);}))
    {
        full.disconnect!method(obj);
    }
    final void disconnect(ClassType)(ClassType obj, void delegate(ClassType,
T1) dg) if(is(ClassType == class))
    {
        full.disconnect(obj, dg);
    }
    final void disconnect(ClassType)(ClassType obj) if(is(ClassType == class))
    {
        full.disconnect(obj);
    }
    final void strongDisconnect(void delegate(Args) dg)
    {
        full.strongDisconnect(dg);
    }
    final ref RestrictedSignal!(Args) restricted()  property
    {
        return full.restricted;
    }
    private FullSignal!(Args) full;
}

Use case:

class Button {
 mixin Signal!() clicked;
 void click() {
   clicked.emit();
 }
}
import std.stdio;
void main() {
Button b=new Button;
b.clicked.strongConnect(() {writeln("I was clicked!");});
b.click();
}

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prev sibling next sibling parent d-bugmail puremagic.com writes:
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Kenji Hara <k.hara.pg gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |pull, rejects-valid



I don't test std.signal2 module, but the two test cases work with my patch.

https://github.com/D-Programming-Language/dmd/pull/1660

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 I don't test std.signal2 module, but the two test cases work with my patch.
 
 https://github.com/D-Programming-Language/dmd/pull/1660


Awesome! This is really great news! Thank you alot! :-) :-) :-) :-D :-) !!!

I tried it and the problem seems to be fixed, but I ran into different issues
(forward reference errors and runtime errors). I still have to figure out
whether this is related to your changes or not. (The runtime errors are
probably because I am still linking to an old phobos version, as I am not able
to build the current one, due to oom problems.)

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 I don't test std.signal2 module, but the two test cases work with my patch.
 
 https://github.com/D-Programming-Language/dmd/pull/1660


std.signal2 works too! Thank you!

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Andrej Mitrovic <andrej.mitrovich gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |andrej.mitrovich gmail.com



10:51:10 PDT ---




 I don't test std.signal2 module, but the two test cases work with my patch.
 
 https://github.com/D-Programming-Language/dmd/pull/1660


 
 std.signal2 works too! Thank you!


 jfanatiker gmx.at: I've tried your std.signals by compiling with 'dmd -c -o-
-unittest signals.d' (the unittest switch is important here), specifically I've
tried two commits for signals2:

04c951e34623e9365a3874c89f43eb997a7b376c (dav1d told me you said this might
work)
4f7aaba0135bdfebfe54cbd645ca3652b0b0eb7a (git-head)

I've tried them both with the current state of Pull 1660, but compilation fails
due to those mixin conflicts. Can you verify this?

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 I've tried them both with the current state of Pull 1660, but compilation fails
 due to those mixin conflicts. Can you verify this?


HEAD definitely won't work at all. The older commit used to work for me, but
pull 1660 changed quite significantly since then. Seeing that there is real use
of my implementation I'm shifting it up in my priority list, prepare to see
some commits in the next days. I will comment on pull 1660 if I find any
issues.

Best regards,
Robert

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15:29:03 PDT ---


 I've tried them both with the current state of Pull 1660, but compilation fails
 due to those mixin conflicts. Can you verify this?


 
 HEAD definitely won't work at all. The older commit used to work for me, but
 pull 1660 changed quite significantly since then. Seeing that there is real use
 of my implementation I'm shifting it up in my priority list, prepare to see
 some commits in the next days. I will comment on pull 1660 if I find any
 issues.
 
 Best regards,
 Robert


Btw why are you using mixin templates instead of a struct? I know the current
std.signals uses it, but it's broken because people keep running into Issue
5028.

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15:29:34 PDT ---


 Issue 5028.


Link: http://d.puremagic.com/issues/show_bug.cgi?id=5028

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 Btw why are you using mixin templates instead of a struct? I know the current
 std.signals uses it, but it's broken because people keep running into Issue
 5028.


Instead is not quite correct, the mixin is just a wrapper around the FullSignal
struct.

Reasoning:  So only containing object can emit signals. (emit is made private)

It is just a convenience wrapper which implements a good default behaviour in
just one line of code. (Make emit private) Otherwise you would have to
instantiate a FullSignal as private and manually provide methods for accessing
the RestrictedSignal for making connections. Not too much work, but a little
annoying.

You can of course use the struct directly if you want.

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07:30:35 PDT ---


 Btw why are you using mixin templates instead of a struct? I know the current
 std.signals uses it, but it's broken because people keep running into Issue
 5028.


 
 Instead is not quite correct, the mixin is just a wrapper around the FullSignal
 struct.


Ah you mean 'RestrictedSignal', the other one has a private alias. Ok then.

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I just finished a new implementation, replacing the template mixin with a
string mixin. You can find it here:

https://github.com/phobos-x/phobosx/blob/master/source/phobosx/signal.d

All unittests pass, you don't need any patched compiler. I still have to add
some more checks and do some polishing, I will also put it in the dub registry.
But you and David seem to have an urgent need, so feel free to try it out
immediately - Be my pre-alpha Testers :-)

Best regards,

Robert

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jfanatiker gmx.at changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Blocks|9347                        |
           Severity|blocker                     |major


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Commit pushed to master at https://github.com/D-Programming-Language/dmd

https://github.com/D-Programming-Language/dmd/commit/864bb113028ec56044c32643c9758b0f5ef8bf2c
fix Issue 8441 - mixin containing template functions causes compiler errors

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Kenji Hara <k.hara.pg gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED



---
Template overload set has been implemented in git head.
For the remain related issue I opened bug 10658.

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