I just transitioned my code to use the new format! macros. I was happy to
get rid of all the .to_str() I had all over the place, but this turned out
not quite as I had expected.
I was hoping I'd be able to simply base on the ToStr trait to print
anything with {:s}. It turns out that actually
On 01/10/13 16:13, Oren Ben-Kiki wrote:
This problem is unique to the String trait. All the other traits
(Bool, Pointer, ...) just allow specifying the trait directly without
getting too clever with string slices. So... I cheated and added a
LowerHex instance my types instead of String
Ah, so simple. I missed it because it is not listed in the formatting
traits list in the documentation.
This would solve half my problem - I'd no longer need to use {:x} but use
the simpler {}, which is great. Thanks!
But it wouldn't solve the problem for printing enums, though. I guess I'd
Huon's suggestion of using fmt::Default is what I would suggest as
well. The behavior you're running into is actually a known feature
of rust today. You'll find in the fmt module implT: Str String for
T, and because of this the compiler will not allow you to implement
String for any type
Perhaps if the type system was smart enough to provide a default
implementation of the Default trait for everything that had the ToStr
trait, and allowing overrides for specific types?
I know that currently this sort of inference is not supported, but it is
intended that it would be possible in
On 01/10/13 16:26, Oren Ben-Kiki wrote:
Perhaps if the type system was smart enough to provide a default
implementation of the Default trait for everything that had the ToStr
trait, and allowing overrides for specific types?
I know that currently this sort of inference is not supported, but
Yes, both suggestions sound very reasonable. It would also eliminate the
need for the Str trait altogether (since the Default fmt function would
avoid the allocation). So there would really be no need for most format
specifiers, except stuff like controlling the base of integers, etc.
On Tue,
Hi,
On Tue, Oct 1, 2013 at 9:13 AM, Oren Ben-Kiki o...@ben-kiki.org wrote:
I know, this is pretty horrible... what is the right thing here? Using
{:s} and keep calling .to_str() everywhere?
Not sure if that helps. But in python there are conversion specifiers
{!s} and {!r} which convert to
