Re: [boost] [convert] no-throw and fallback feature

Subject: Re: [boost] [convert] no-throw and fallback feature
From: Stewart, Robert (Robert.Stewart_at_[hidden])
Date: 2011-05-09 11:13:28

Vicente BOTET wrote:
> De : "Vladimir Batov"
> > From: "Vicente BOTET"
>
> > > I was thinking on the fallback feature a little bit more
> > > and I've the impression that we can get it for free. If we
> > > accept that we need a no-throw function such as
> > > try_convert_to that returns an optional Target we can have
> > > the fallback using the optional::get_value_or function
> > >
> > > auto r = try_convert_to(*int*)(s);
> > > int i = r.get_value_or(fallback);
> > > ...

The issue raised before is that "try" indicates a bool return type.  Perhaps "maybe_as" would work?

   auto o(convert::maybe_as<int>(s));

However, I do like the use of get_value_or().

> > > I don't know if it is worth adding a function that does all
> > > in one
> > >
> > > int i = convert_to_or(*int*)(s, fallback);

Don't forget the name when in its namespace and with the type specified clearly: convert::convert_to_or<int>(s, fallback).  The repetition of "convert" is not ideal, but no different than "convert_cast" and stands up well with a using declaration or directive.  Unfortunately, "to_or<int>" isn't right.  It suggests something other than int is the desire.

I can't think of a good name, so I'm inclined to reject this function.  If a better name arises, I can certainly see some value in including such a function, but at some point, there get to be too many ways to do a thing and that, itself, confuses matters.  Thus, this function must be considered in light of the entire API.

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





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