There were a few ambiguous error messages which look like they could have
cropped up from either the rust compiler for the format string parser. To
differentiate, the prefix 'invalid format string' is now added in front of all
format string errors.
cc #9970
* Allow named parameters to specify width/precision
* Intepret the format string '0$' as "width is the 0th argument" instead of
thinking the lone '0' was the sign-aware-zero-padding flag. To get both you'd
need to put '00$' which makes more sense if you want both to happen.
Closes#9669
It is simply defined as `f64` across every platform right now.
A use case hasn't been presented for a `float` type defined as the
highest precision floating point type implemented in hardware on the
platform. Performance-wise, using the smallest precision correct for the
use case greatly saves on cache space and allows for fitting more
numbers into SSE/AVX registers.
If there was a use case, this could be implemented as simply a type
alias or a struct thanks to `#[cfg(...)]`.
Closes#6592
The mailing list thread, for reference:
https://mail.mozilla.org/pipermail/rust-dev/2013-July/004632.html
It was a little ambiguous before how explicitl positional parameters and
implicit positional parameters intermingled, and this clarifies how the two
intermingle. This also updates a little bit of documentation/code examples
elsewhere as well.
It was a little ambiguous before how explicitl positional parameters and
implicit positional parameters intermingled, and this clarifies how the two
intermingle. This also updates a little bit of documentation/code examples
elsewhere as well.
This renames the syntax-extension file to format from ifmt, and it also reduces
the amount of complexity inside by defining all other macros in terms of
format_args!
The purpose of this macro is to further reduce the number of allocations which
occur when dealing with formatting strings. This macro will perform all of the
static analysis necessary to validate that a format string is safe, and then it
will wrap up the "format string" into an opaque struct which can then be passed
around.
Two safe functions are added (write/format) which take this opaque argument
structure, unwrap it, and then call the unsafe version of write/format (in an
unsafe block). Other than these two functions, it is not intended for anyone to
ever look inside this opaque struct.
The macro looks a bit odd, but mostly because of rvalue lifetimes this is the
only way for it to be safe that I know of.
Example use-cases of this are:
* third-party libraries can use the default formatting syntax without any
forced allocations
* the fail!() macro can avoid allocating the format string
* the logging macros can avoid allocation any strings
The trait will keep the `Iterator` naming, but a more concise module
name makes using the free functions less verbose. The module will define
iterables in addition to iterators, as it deals with iteration in
general.
This removes the stacking of type parameters that occurs when invoking
trait methods, and fixes all places in the standard library that were
relying on it. It is somewhat awkward in places; I think we'll probably
want something like the `Foo::<for T>::new()` syntax.
See discussion in #8489, but this selects option 3 by adding a `Default` trait to be implemented by various basic types.
Once this makes it into a snapshot I think it's about time to start overhauling all current use-cases of `fmt!` to move towards `ifmt!`. The goal is to replace `%X` with `{}` in 90% of situations, and this commit should enable that.
