digitalmars.D.bugs - [Issue 3180] New: Need delegate covariance and contravariance
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http://d.puremagic.com/issues/show_bug.cgi?id=3180
Summary: Need delegate covariance and contravariance
Product: D
Version: unspecified
Platform: Other
OS/Version: Windows
Status: NEW
Keywords: spec
Severity: normal
Priority: P2
Component: DMD
AssignedTo: nobody puremagic.com
ReportedBy: rayerd.wiz gmail.com
import std.stdio;
class A {}
class B : A {}
class X
{
A foo() { return new A; }
}
class Y : X
{
B foo() { return new B; }
}
class V
{
void foo(B){}
}
void main()
{
// Class Covariance (supported already)
{
X x = new X;
Y y = new Y;
A r = x.foo();
A s = y.foo();
B t = y.foo();
writeln(r); // A
writeln(s); // B
writeln(t); // B
}
// Delegate Covariance
{
A delegate() f = delegate A() { return new A; }; // Of course, OK.
writeln(f()); // A
//A delegate() g = delegate B() { return new B; }; // Need support the
covariance
//writeln(g()); // This should be B.
}
// Delegate Contravariance
{
V v = new V;
void delegate(B) g = &v.foo; // Of course, OK.
//void delegate(A) f = &v.foo; // Need suport the contravariance.
}
}
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Jul 15 2009
d-bugmail puremagic.com
http://d.puremagic.com/issues/show_bug.cgi?id=3180
Steven Schveighoffer <schveiguy yahoo.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |schveiguy yahoo.com
Severity|normal |enhancement
18:13:10 PDT ---
Your contravariance example is not valid, you cannot call foo(B) with an A.
It should be:
class V
{
void foo(A);
}
...
V v = new v;
void delegate(B) g = &v.foo; // contravariance
Also this is somewhat of a duplicate of bug 3075. Although you do bring up
covariance for delegates, which should be implemented at the same time as
contravariance.
Sadly, Walter has decided the prior bug is an invalid enhancement request, so
most likely nothing will come of this request either.
I think the only possible way this may be included is if someone implements it
and submits it as a patch to dmd.
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Jul 15 2009
http://d.puremagic.com/issues/show_bug.cgi?id=3180 16:55:58 PDT ---Your contravariance example is not valid, you cannot call foo(B) with an A. It should be: class V { void foo(A); } ... V v = new v; void delegate(B) g = &v.foo; // contravarianceSorry, it is my mistake.Also this is somewhat of a duplicate of bug 3075. Although you do bring up covariance for delegates, which should be implemented at the same time as contravariance. Sadly, Walter has decided the prior bug is an invalid enhancement request, so most likely nothing will come of this request either.I think the only possible way this may be included is if someone implements it and submits it as a patch to dmd.I am trying to make some dmd patchs, but it is difficult yet. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jul 17 2009
http://d.puremagic.com/issues/show_bug.cgi?id=3180
Steven Schveighoffer <schveiguy yahoo.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |dsimcha yahoo.com
10:08:31 PDT ---
*** Issue 5742 has been marked as a duplicate of this issue. ***
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Mar 16 2011
http://d.puremagic.com/issues/show_bug.cgi?id=3180
yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bearophile_hugs eml.cc
*** Issue 3833 has been marked as a duplicate of this issue. ***
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Jun 08 2011
http://d.puremagic.com/issues/show_bug.cgi?id=3180 *** Issue 4000 has been marked as a duplicate of this issue. *** -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 08 2011
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yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords|spec |patch, rejects-valid
CC| |yebblies gmail.com
Summary|Need delegate covariance |Covariance of
|and contravariance |delegates/function pointers
Severity|enhancement |normal
The enhancement portion of the original report is a dupe of Issue 3075, which
has been marked INVALID by Walter.
In the comments he states that delegate covariance is supposed to work, so that
part of the report is definitely a bug.
https://github.com/D-Programming-Language/dmd/pull/96
should fix this report for function pointers.
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Jun 08 2011
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yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |zan77137 nifty.com
*** Issue 4218 has been marked as a duplicate of this issue. ***
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Jun 13 2011
http://d.puremagic.com/issues/show_bug.cgi?id=3180
yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bugzilla kyllingen.net
*** Issue 6524 has been marked as a duplicate of this issue. ***
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Aug 18 2011
http://d.puremagic.com/issues/show_bug.cgi?id=3180
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
CC| |bugzilla digitalmars.com
Resolution| |FIXED
02:38:23 PDT ---
Partial fix:
https://github.com/D-Programming-Language/dmd/commit/306df8eaa6f8a987f76f401a1e03d8edf1f1e2ae
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Sep 02 2011
http://d.puremagic.com/issues/show_bug.cgi?id=3180
yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords|patch |
Status|RESOLVED |REOPENED
Platform|Other |All
Resolution|FIXED |
OS/Version|Windows |All
Partial is partial.
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Sep 06 2011
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yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |clugdbug yahoo.com.au
*** Issue 3267 has been marked as a duplicate of this issue. ***
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Sep 06 2011
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yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |patch
Severity|normal |critical
Part was fixed by
https://github.com/D-Programming-Language/dmd/commit/dfb683f63ec89709b0bf2760ef3b2a249ce320eb
Raising importance as while not a regression, this fixes one. (bug 6352)
Pull for the remaining common type bugs:
https://github.com/D-Programming-Language/dmd/pull/368
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Sep 06 2011
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yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |patch
Severity|normal |critical
Part was fixed by
https://github.com/D-Programming-Language/dmd/commit/dfb683f63ec89709b0bf2760ef3b2a249ce320eb
Raising importance as while not a regression, this fixes one. (bug 6352)
Pull for the remaining common type bugs:
https://github.com/D-Programming-Language/dmd/pull/368
Part was fixed by
https://github.com/D-Programming-Language/dmd/commit/dfb683f63ec89709b0bf2760ef3b2a249ce320eb
Raising importance as while not a regression, this fixes one. (bug 6352)
Pull for the remaining common type bugs:
https://github.com/D-Programming-Language/dmd/pull/368
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Sep 06 2011
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yebblies <yebblies gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |patch
Severity|normal |critical
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|REOPENED |RESOLVED
Resolution| |FIXED
Part was fixed by
https://github.com/D-Programming-Language/dmd/commit/dfb683f63ec89709b0bf2760ef3b2a249ce320eb
Raising importance as while not a regression, this fixes one. (bug 6352)
Pull for the remaining common type bugs:
https://github.com/D-Programming-Language/dmd/pull/368
Part was fixed by
https://github.com/D-Programming-Language/dmd/commit/dfb683f63ec89709b0bf2760ef3b2a249ce320eb
Raising importance as while not a regression, this fixes one. (bug 6352)
Pull for the remaining common type bugs:
https://github.com/D-Programming-Language/dmd/pull/368
23:28:48 PDT ---
https://github.com/D-Programming-Language/dmd/commit/77bed134d06e6314c5b65465068f554b3f2c2e8d
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Sep 16 2011
http://d.puremagic.com/issues/show_bug.cgi?id=3180
09:04:50 PDT ---
import std.stdio;
class Base {}
class Derived : Base {}
class X
{
Base foo() { return new Base; }
}
class Y : X
{
Derived foo() { return new Derived; }
}
void main()
{
// Covariance is good
{
Base delegate() f = delegate Derived() { return new Derived; };
writefln("delegate convariance is <%s>", f().toString() == "a.Derived"
? "OK" : "NG");
}{
static Derived fp() { return new Derived; }
Base function() f = &fp;
writefln("function pointer covariance is <%s>", f().toString() ==
"a.Derived" ? "OK" : "NG");
}
// Contravariance is BAD
{
auto c = new class { void foo(Base){} };
// GOOD
void delegate(Base) f = &c.foo;
f(new Base);
f(new Derived);
// BAD
void delegate(Derived) g = &c.foo;
g(new Derived);
}
}
a.d(33): Error: cannot implicitly convert expression (&c.foo) of type void
delegate(Base) to void delegate(Derived)
---
Why is "Status" "RESOLVED-FIXED"?
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Sep 17 2011
http://d.puremagic.com/issues/show_bug.cgi?id=3180Why is "Status" "RESOLVED-FIXED"?I assume you're asking why this report was marked as fixed when delegate covered by another report which has been rejected. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Sep 17 2011