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Subject: Re: [boost] [review] string convert
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2011-05-04 15:01:27

Matthew Chambers wrote:
> On 5/4/2011 1:18 PM, Stewart, Robert wrote:
> > try_convert(s, i) doesn't tell me whether s is being
> > converted to i's type or i to s's type.
> I don't think this is a problem in practice. C#'s TryParse has
> the same semantics, albeit you're forced to use the out
> keyword on the second argument, so perhaps that's not a fair
> comparison.

I don't think it's a fair comparison. I realize that folks can become accustomed to "try_convert" and learn to read it correctly, but why make it harder than it needs to be?

> > convert_cast(s, 17) has the same problem and breaks with the
> > new-style cast pattern.
> What is the breaking aspect?

New-style casts are of the form xxx_cast<T>(S). Thus, that has to be convert_cast<int>(s, 17) to fit.

> > The target type should be required in all cases, I suspect,
> > to make things clearer:
> >
> > try_convert_to<int>(s, i) clearly indicates that int is the
> > target type.
> >
> > convert_cast<int>(s, 17) is likewise better.
> Yes, but thanks to type inference users are free to write
> try_convert_to(s, i) instead and that's even worse than
> try_convert(s, i). :)

You can make the second argument non-deducible thus requiring the target type.

Rob Stewart robert.stewart_at_[hidden]
Software Engineer using std::disclaimer;
Dev Tools & Components
Susquehanna International Group, LLP

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