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From Martin Sebor <>
Subject Re: Another potential hole in the tuple specs
Date Tue, 08 Jul 2008 19:13:31 GMT
Eric Lemings wrote:
>> -----Original Message-----
>> From: Martin Sebor [] 
>> Sent: Tuesday, July 08, 2008 10:52 AM
>> To:
>> Subject: Re: Another potential hole in the tuple specs
>> Eric Lemings wrote:
>> [...]
>>> A const assignment operator?  Sounds unorthodox but I'll try it out.
>>> My current workaround is to declare std::ignore mutable (i.e.
>>> non-const).  A const assignment operator (if it works) would be
>>> preferable; no visible workaround required.
>> Remember that even the absence (or presence) of the const
>> qualifier on things like std::ignore can be detected by
>> conformance test suites so dropping it is not a viable
>> option.
> Assuming the draft standard is actually correct, that is. 
> In this case,
> I don't think there is any real need for std::ignore to be a constant
> really.  (Thinking about asking whether std::ignore really needs to be a
> constant on the committee reflector.)

IMO, there is no need for it not to be, and being constant
is more efficient than not (can be stored in ROM).

> I tried making std::ignore const and adding const to the internal
> assignment operator.  I also tried adding overloads for const and
> non-const assignment.  Still got errors in all cases.
> The only other recourse I can think of is to use remove_const on the
> element types where appropriate.

ignore is declared const in Boost so there must be a way
to implement tie() without declaring the object non-const.


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