digitalmars.D.bugs - [Issue 10009] New: foreach_reverse and AA.byKey/byValue
- d-bugmail puremagic.com (24/24) Apr 29 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10009
- d-bugmail puremagic.com (11/11) Apr 29 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10009
- d-bugmail puremagic.com (12/14) Apr 29 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10009
- d-bugmail puremagic.com (15/19) Apr 29 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10009
- d-bugmail puremagic.com (7/13) Apr 29 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10009
- d-bugmail puremagic.com (14/15) Apr 29 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10009
- d-bugmail puremagic.com (7/7) May 02 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10009
- d-bugmail puremagic.com (10/10) May 02 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10009
- d-bugmail puremagic.com (18/18) May 03 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10009
- d-bugmail puremagic.com (21/25) May 03 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10009
- d-bugmail puremagic.com (6/7) May 04 2013 Which is essentially the same problem as bug# 6251.
- d-bugmail puremagic.com (11/12) May 06 2013 http://d.puremagic.com/issues/show_bug.cgi?id=10009
http://d.puremagic.com/issues/show_bug.cgi?id=10009
Summary: foreach_reverse and AA.byKey/byValue
Product: D
Version: D2
Platform: All
OS/Version: All
Status: NEW
Severity: normal
Priority: P2
Component: DMD
AssignedTo: nobody puremagic.com
ReportedBy: henning still-hidden.de
PDT ---
void main() {
auto aa = [1 : 2, 2 : 3];
foreach_reverse (e; aa.byKey()) { }
}
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test.d(4): Error: invalid foreach aggregate aa.byKey().state
-----
foreach works like a charm.
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Apr 29 2013
d-bugmail puremagic.com
http://d.puremagic.com/issues/show_bug.cgi?id=10009
Andrej Mitrovic <andrej.mitrovich gmail.com> changed:
What |Removed |Added
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CC| |andrej.mitrovich gmail.com
13:04:56 PDT ---
I think foreach_reverse was only ever meant to be used with arrays (and is
scheduled for deprecations), for ranges you can use retro() from std.algorithm.
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Apr 29 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10009
bearophile_hugs eml.cc changed:
What |Removed |Added
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CC| |bearophile_hugs eml.cc
I think foreach_reverse was only ever meant to be used with arrays (and is
scheduled for deprecations), for ranges you can use retro() from std.algorithm.
I have hundreds of usages of foreach_reverse in my D2 codebase. You aren't
going to deprecate it. retro() is not nearly as efficient for arrays.
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Apr 29 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10009I have hundreds of usages of foreach_reverse in my D2 codebase. You aren't going to deprecate it. retro() is not nearly as efficient for arrays.Sorry, my brain was switched off. And the usages are probably under one hundred. -----------------I think foreach_reverse was only ever meant to be used with arrays (and is scheduled for deprecations), for ranges you can use retro() from std.algorithm.Maybe the compiler can rewrite this: foreach_reverse(x; someRange) as: foreach(x; someRange.retro) But I don't know what problems this causes. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
Apr 29 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10009 16:06:07 PDT ---Why is retro less efficient though? -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------I think foreach_reverse was only ever meant to be used with arrays (and is scheduled for deprecations), for ranges you can use retro() from std.algorithm.I have hundreds of usages of foreach_reverse in my D2 codebase. You aren't going to deprecate it. retro() is not nearly as efficient for arrays.
Apr 29 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10009
Jonathan M Davis <jmdavisProg gmx.com> changed:
What |Removed |Added
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CC| |jmdavisProg gmx.com
PDT ---
Why is retro less efficient though?
Probably something to do with how the decoding is done and/or some extra steps
which can be skipped. I don't think that I ever investigated it in detail, but
I know that I used foreach_reverse in some functions in std.string because it
was definitely faster according to the benchmarks that I did, much as I would
prefer to never use it.
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Apr 29 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10009 04:01:37 PDT --- Well we better decide whether or not foreach_reverse is actually scheduled for deprecation. If it is then we shouldn't add more features to it. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
May 02 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10009
yebblies <yebblies gmail.com> changed:
What |Removed |Added
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CC| |yebblies gmail.com
Leave foreach_reverse alone!
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May 02 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10009
Steven Schveighoffer <schveiguy yahoo.com> changed:
What |Removed |Added
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CC| |schveiguy yahoo.com
14:43:31 PDT ---
The problem I see with removing foreach_reverse is that the compiler actually
rewrites it directly instead of calling a function. Requiring to use retro
when it is in std.range is not good for modularity.
In addition, foreach_reverse(x..y) is nice to use instead of some combination
of ranges.
However, I don't think foreach_reverse is valid for this use case. An AA is
only forward-traversable. foreach_reverse is not possible, as buckets are
stored as singly-linked lists. If you want that, you need to first capture it
as an array.
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May 03 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10009However, I don't think foreach_reverse is valid for this use case. An AA is only forward-traversable. foreach_reverse is not possible, as buckets are stored as singly-linked lists. If you want that, you need to first capture it as an array.Yet this compiles: import std.stdio: writeln; void main() { auto aa = [1: 2, 2: 3]; foreach (k, v; aa) writeln(k, " ", v); foreach_reverse (k, v; aa) writeln(k, " ", v); } And outputs: 1 2 2 3 1 2 2 3 The foreach seems to give the same sequence as the foreach_reverse :-) -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
May 03 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10009 PDT ---The foreach seems to give the same sequence as the foreach_reverse-- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
May 04 2013
http://d.puremagic.com/issues/show_bug.cgi?id=10009 11:25:25 PDT ---Not exactly. AA is a type, not a delegate. It is allowed to define opApplyReverse. A delegate cannot possibly be valid with foreach_reverse (and that bug should be killed with prejudice). Even if opApplyReverse is defined for AAs, the implementation will be wrong (as bearophile described) because it's built from singly linked lists. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------
May 06 2013