Re: [boost] Plea for addition of stream_cast

From: Kevlin Henney (kevlin_at_[hidden])
Date: 2000-06-01 16:26:52

In message <02a801bfca4d$9d434fb0$3e116e97_at_[hidden]>, Ed Brey
<brey_at_[hidden]> writes
>For the unchecked version, Dave Abrahams had suggested stream_cast
>with a std::nothrow_t parameter.  The decision on what to call the
>unchecked version probably should be based on its semantics.
[...]
>In summary, it might be that the non-throwing version is used so
>rarely that it's not worth having.  If it is useful, the next question
>is how common is it that the default initialized target is desired if
>there is an error?  If the answer isn't "almost always", the target
>should be passed in by reference.  Then finally, what should it be
>called?  Unchecked is somewhat misleading, since there is a check
>preventing target from containing just garbage if there is a failure.
>Instead something term that differentiates what happens if the check
>fails seems more appropriate, although I don't have a suggestion for
>this.

Just realised that I haven't responded to this thread. Unfortunately I'm
a bit short of time at the moment, and out of email contact as of
tomorrow for the next week, otherwise I would give a longer, more
detailed answer. Anyway, the highlights:

* I have the default initialisation to be useful and a sensible default,
following the script soft-failure, "do something sensible" model, hence
why the original version did this.

* An exception throwing variant is also useful.

* Other variants wrt how conversions are done are also useful, ie
different interpretation methods (not necessarily stream-based).

* A trait based technique can be used that accommodates this variability
whilst maintaining a single cast function.

I will pick up any discussion and comments next week, produce a version
of the code and, importantly, worked examples for further feedback.
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