• d-bugmail puremagic.com (37/37) Oct 14 2013 http://d.puremagic.com/issues/show_bug.cgi?id=11252

d-bugmail puremagic.com writes:

http://d.puremagic.com/issues/show_bug.cgi?id=11252

           Summary: "in" operator for std.range.iota
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: Phobos
        AssignedTo: nobody puremagic.com
        ReportedBy: bearophile_hugs eml.cc



In Python sometimes I have code like this that I'd like to translate to D, it
contains a pattern that was forbidden in D:

if (... and 1 < foo(2) < 10 and ...): ...


If the call to foo() is not pure or you don't want the risk of calling it two
times, in D you have to split that if() in two and use an extra variable:


if (...) {
    const temp = foo(2);
    if (temp > 1 && temp < 10 && ...) { ...
    }
}


To avoid some of such problems I suggest to add the support for the "in"
operator to iota():

if (... && foo(2) in iota(1, 11) && ...) { ...
}


In another ehnancement request I've suggested to support the "[]" syntax in
iota():

if (... && foo(2) in iota!"[]"(1, 10) && ...) { ...
}


This usage of iota is useful only for numerical intervals, so it doesn't cover
all usages of the Python x<y<z syntax, but I think it covers most of my
translations from Python.

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