Why not create a trait Localizer , and make Box<Localizer> fmt!able? -Manish Goregaokar
On Mon, Aug 25, 2014 at 9:59 PM, Matthieu Monrocq < matthieu.monr...@gmail.com> wrote: > While not possible today, there is actually nothing preventing you to > create a safe alternative (or even improving format so it works in this > way). > > In a sense, a formatting function has two set of inputs: > > - the format itself, from which you extract a set of constraints (expected > type-signature) > - the arguments to format, which can be seen as a single tuple (provided > type-signature) > > And as long as you can ensure at compile time that you never attempt to > apply an "expected type-signature" to an incompatible "provided > type-signature", then you are safe. > > > I would suppose that as far as having runtime formats go, you would need > to introduce an intermediary step: the expected type-signature. > > You could have a "Format" object, generic over the expected > type-signature, and a "new" constructor method taking a &str and returning > an "Option<Format<...>>". > > > Now, you have two phases: > > - the "new" constructor checks, at runtime, that the specified format > matches the expected type-signature > - the compiler checks, at compile-time, that the provided type-signature > (arguments) match the expected type-signature (or it can be coerced to) > > It might require variadic generics and subtle massaging of the type > system, however I do think it would be possible. > > > It might not be the best way to attack the issue though. > > > > On Mon, Aug 25, 2014 at 1:33 AM, Kevin Ballard <ke...@sb.org> wrote: > >> It’s technically possible, but horribly unsafe. The only thing that makes >> it safe to do normally is the syntax extension that implements `format!()` >> ensures all the types match. If you really think you need this, you can >> look at the implementation of core::fmt. But it’s certainly not appropriate >> for localization, or template engines. >> >> -Kevin Ballard >> >> > On Aug 24, 2014, at 2:48 PM, Vadim Chugunov <vadi...@gmail.com> wrote: >> > >> > Hi, >> > Is there any way to make Rust's fmt module to consume format template >> specified at runtime? >> > This might be useful for localization of format!'ed strings, or, if one >> wants to use format! as a rudimentary template engine. >> > _______________________________________________ >> > Rust-dev mailing list >> > Rust-dev@mozilla.org >> > https://mail.mozilla.org/listinfo/rust-dev >> >> >> _______________________________________________ >> Rust-dev mailing list >> Rust-dev@mozilla.org >> https://mail.mozilla.org/listinfo/rust-dev >> >> > > _______________________________________________ > Rust-dev mailing list > Rust-dev@mozilla.org > https://mail.mozilla.org/listinfo/rust-dev > >
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