Re: [boost] Plea for addition of stream_cast

From: Ed Brey (brey_at_[hidden])
Date: 2000-06-29 08:34:20

From: "Kevlin Henney" <kevlin_at_[hidden]>
> I would contend that this leads to three ways of using the cast rather
> than two:
>
> (1) Use it so that it throws on failure.
> (2) Use it so that it does nothing on failure and defaults the value.
> (3) Use it so that it returns a status on failure.
>
> I personally would use (1) if I wanted to know about failure and (2) if
> I didn't, which makes (3) seem a little like gold plating.

I agree with your take on (3), other than when conversion failures are not
exceptional cases.  One problem is that if failures are frequent, exceptions
may be too slow.  Also, there is the issue with how easy/cumbersome the code
is to write.  A previous post [1] went into this in more detail, but the
summary is that try blocks work well when there are many conversions and
possibly other operations for which failure can be handled uniformly,
whereas if there is unique recovery action for each potential failed
conversion, then having the status returned is quite convenient.

[1] http://www.egroups.com/message/boost/3437?