[Issue 4471] New: rebindable() helper function

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=4471

           Summary: rebindable() helper function
           Product: D
           Version: D2
          Platform: All
        OS/Version: All
            Status: NEW
          Keywords: patch
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: nobody at puremagic.com
        ReportedBy: bearophile_hugs at eml.cc


--- Comment #0 from bearophile_hugs at eml.cc 2010-07-16 05:21:15 PDT ---
A helper function for Rebindable!() can help remove some noise from the code,
this is a first try:


import std.typecons, std.traits;

template isImmutable(T) {
    enum bool isImmutable = is(const(T) == T) || is(immutable(T) == T);
}

Rebindable!T rebindable(T)(T obj)
  if ((is(T == class) || is(T == interface) || isArray!T) && isImmutable!T) {
    return Rebindable!T(obj);
}

// usage example
import std.stdio;
class Foo {}
void main() {
    auto a = rebindable(new immutable(Foo));
    assert(a.sizeof == 4);
    a = new immutable(Foo);
}


I don't know if isImmutable!() works well in all cases, I have not tested it
much. But a template like isImmutable can be useful in Phobos.

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