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digitalmars.D.bugs - [Issue 14625] New: opIndex() doesn't work on foreach container


          Issue ID: 14625
           Summary: opIndex() doesn't work on foreach container iteration
           Product: D
           Version: D2
          Hardware: All
                OS: All
            Status: NEW
          Keywords: rejects-valid
          Severity: normal
          Priority: P1
         Component: DMD
          Assignee: nobody puremagic.com
          Reporter: k.hara.pg gmail.com

A non-range container object iteration `foreach (e; c)` is
implicitly converted to a range iteration, by application of
implicit slicing like as `foreach (e; c[])`.

(Maybe the feature is not well documented in website?

struct Range
     property bool empty() { return true; }
     property int front() { return 0; }
    void popFront() {}
struct Container
    Range opSlice() { return Range(); }
void main()
    Container c;
    foreach (e; c) {}

On the other hand, new integrated array operator overloading says as follows:
 To overload a[], simply define opIndex with no parameters:
But, it does not work on the container iteration. Test case is: // Range struct is same as above struct Container { Range opIndex() { return Range(); } Range opSlice() { assert(0); } } void main() { Container c; //foreach (e; c) {} // asserts in opSlice(), NG foreach (e; c[]) {} // calls c.opIndex(), OK } The orignal post in d.learn forum: http://forum.dlang.org/thread/vhsyxrroterdmqpgcesc forum.dlang.org --
May 27 2015