digitalmars.D.bugs - [Issue 8261] New: std.traits.ParameterTypeTuple may break existing codes
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http://d.puremagic.com/issues/show_bug.cgi?id=8261
Summary: std.traits.ParameterTypeTuple may break existing codes
Product: D
Version: D2
Platform: All
OS/Version: All
Status: NEW
Severity: normal
Priority: P2
Component: DMD
AssignedTo: nobody puremagic.com
ReportedBy: k.hara.pg gmail.com
--- Comment #0 from Kenji Hara <k.hara.pg gmail.com> 2012-06-18 08:26:10 PDT ---
In 2.060head, is(FuncType PT == function) -> PT contains parameter identifiers.
This change is introduced the commit:
https://github.com/D-Programming-Language/dmd/commit/65acb8ca382f3cd2abea058552d78c147163a8fa
It is useful for more metaprogramming, but this change may break existing codes
that using std.traits.ParameterTypeTuple. See below sample code:
void foo(int num, string name, int[int] map){}
pragma(msg, ParameterTypeTuple!foo);
// In 2.059, prints (int, string, int[int])
// In 2.060head, prints (int num, string name, int[int] map)
void bar(ParameterTypeTuple!foo num) {}
// Error: function test.bar parameter bar.num is already defined
====
If we change the implementation of ParameterTypeTuple template like follows:
template ParameterTypeTuple(func...)
if (func.length == 1 && isCallable!func)
{
static if (is(FunctionTypeOf!(func) P == function))
{
//alias P ParameterTypeTuple;
// Remove parameter names that original function has.
template Id(T) { alias T Id; }
alias staticMap!(Id, P) ParameterTypeTuple;
}
else
static assert(0, "argument has no parameters");
}
We can get 'a tuple that contains only parameter types', but it also removes
parameter storage class... breaking existing codes REVISITED!
void foo(ref int x){}
pragma(msg, ParameterTypeTuple!foo); // will prints (int), not (ref int)
====
In current dmd, all of function parameters have names, written by user, or
named by compiler internally (e.g. _param_0). Then we never get a tuple of
'parameter type with storage class but unnamed'.
Then, if we want to parameter type tuple with storage classes, we cannot remove
parameter name informations from the tuple.
As far as I know, there is no workaround. So I think we should revert the
commit 65acb8ca.
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d-bugmail puremagic.com
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Manu <turkeyman gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |turkeyman gmail.com
--- Comment #1 from Manu <turkeyman gmail.com> 2012-06-18 13:31:45 PDT ---
(In reply to comment #0)
In 2.060head, is(FuncType PT == function) -> PT contains parameter identifiers.
This change is introduced the commit:
https://github.com/D-Programming-Language/dmd/commit/65acb8ca382f3cd2abea058552d78c147163a8fa
It is useful for more metaprogramming, but this change may break existing codes
that using std.traits.ParameterTypeTuple. See below sample code:
void foo(int num, string name, int[int] map){}
pragma(msg, ParameterTypeTuple!foo);
// In 2.059, prints (int, string, int[int])
// In 2.060head, prints (int num, string name, int[int] map)
void bar(ParameterTypeTuple!foo num) {}
// Error: function test.bar parameter bar.num is already defined
====
If we change the implementation of ParameterTypeTuple template like follows:
template ParameterTypeTuple(func...)
if (func.length == 1 && isCallable!func)
{
static if (is(FunctionTypeOf!(func) P == function))
{
//alias P ParameterTypeTuple;
// Remove parameter names that original function has.
template Id(T) { alias T Id; }
alias staticMap!(Id, P) ParameterTypeTuple;
}
else
static assert(0, "argument has no parameters");
}
We can get 'a tuple that contains only parameter types', but it also removes
parameter storage class... breaking existing codes REVISITED!
void foo(ref int x){}
pragma(msg, ParameterTypeTuple!foo); // will prints (int), not (ref int)
====
In current dmd, all of function parameters have names, written by user, or
named by compiler internally (e.g. _param_0). Then we never get a tuple of
'parameter type with storage class but unnamed'.
Then, if we want to parameter type tuple with storage classes, we cannot remove
parameter name informations from the tuple.
As far as I know, there is no workaround. So I think we should revert the
commit 65acb8ca.
Can the new behaviour be expressed with a new ParameterTuple! trait or
something?
ParameterTypeTuple! makes sense as just types, but it would be nice to see a
suite: ParameterTyple! with all details, ParameterNameTuple! just names,
ParameterDefaultArgTuple!, you get the idea... ?
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Jun 18 2012
http://d.puremagic.com/issues/show_bug.cgi?id=8261
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bugzilla digitalmars.com
--- Comment #2 from Walter Bright <bugzilla digitalmars.com> 2012-06-18
17:16:17 PDT ---
You're right, it does break existing code. I thought it was a worthwhile
tradeoff to get the functionality Manu needed.
But perhaps Manu's idea to do this tuple with a __traits is a better idea.
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http://d.puremagic.com/issues/show_bug.cgi?id=8261 --- Comment #3 from Kenji Hara <k.hara.pg gmail.com> 2012-06-18 17:33:11 PDT --- (In reply to comment #2)You're right, it does break existing code. I thought it was a worthwhile tradeoff to get the functionality Manu needed. But perhaps Manu's idea to do this tuple with a __traits is a better idea.See also the notes in github. https://github.com/D-Programming-Language/dmd/commit/65acb8ca382f3cd2abea058552d78c147163a8fa#commitcomment-1473583 -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Jun 18 2012
http://d.puremagic.com/issues/show_bug.cgi?id=8261
Kenji Hara <k.hara.pg gmail.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |pull, rejects-valid
Severity|normal |regression
--- Comment #4 from Kenji Hara <k.hara.pg gmail.com> 2012-06-19 07:11:27 PDT ---
I think this is a regression in 2.060head.
https://github.com/D-Programming-Language/dmd/pull/1018
To support getting parameter names, there are two pulls.
1. Add new trait: __traits(parameterNames, func)
https://github.com/D-Programming-Language/dmd/pull/951
2. An implementation of my idea: __traits(identifier, typeof(func))
https://github.com/D-Programming-Language/dmd/pull/1017
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Jun 19 2012
http://d.puremagic.com/issues/show_bug.cgi?id=8261
Walter Bright <bugzilla digitalmars.com> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED
--- Comment #5 from Walter Bright <bugzilla digitalmars.com> 2012-07-01
00:44:00 PDT ---
Done in an alternate way:
https://github.com/D-Programming-Language/dmd/commit/08811d7abbb6cd6eeabef041122e1673b2044251
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Jul 01 2012