Thread overview
[Issue 3444] New: foreach(i, elem; range) should work
Oct 27, 2009
David Simcha
Dec 10, 2009
David Simcha
Dec 10, 2009
David Simcha
Jun 10, 2010
Shin Fujishiro
October 27, 2009
http://d.puremagic.com/issues/show_bug.cgi?id=3444

           Summary: foreach(i, elem; range) should work
           Product: D
           Version: 2.035
          Platform: Other
        OS/Version: Windows
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: nobody@puremagic.com
        ReportedBy: dsimcha@yahoo.com


--- Comment #0 from David Simcha <dsimcha@yahoo.com> 2009-10-26 18:38:59 PDT ---
Currently, one cannot do a foreach statement over a range that also gives the index.  This is inconsistent with arrays.  I'm not sure if it's the best fix, but at least a temporary fix is to mix this thing into all ranges:

template CountForeach(I) {
    int opApply(int delegate(ref I, ref typeof(this.front())) dg) {
        I index = 0;
        int result;
        foreach(elem; this) {
            result = dg(index, elem);
            if(result) {
                break;
            }
            ++index;
        }

        return result;
    }
}

Usage:

struct SomeRange {

    SomeType front() { return something; }

    void popFront() {
        doStuff();
    }

    bool empty() {
        return amIEmpty();
    }

    mixin CountForeach!size_t;
}

void main() {
    SomeRange someRange;

    foreach(elem; someRange) {}  // Uses range interface directly.

    foreach(i, elem; someRange) {}  // Uses the mixin;
}

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David Simcha <dsimcha@yahoo.com> changed:

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


--- Comment #1 from David Simcha <dsimcha@yahoo.com> 2009-12-09 20:03:17 PST ---
Fixed.

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David Simcha <dsimcha@yahoo.com> changed:

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


--- Comment #2 from David Simcha <dsimcha@yahoo.com> 2009-12-09 20:37:20 PST ---
Argh, accidentally marked the wrong bug fixed.

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--- Comment #3 from Shin Fujishiro <rsinfu@gmail.com> 2010-06-09 23:25:08 PDT ---
Created an attachment (id=659)
patch against dmd r526

Implemented foreach(i, e; r) and foreach_reverse(i, e; r).
For reverse iteration with index, r must have a length property.

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