custom-format
This crate extends the standard formatting syntax with custom format specifiers, by providing custom formatting macros.
It uses :
(a space and a colon) as a separator before the format specifier, which is not a syntax currently accepted and allows supporting standard specifiers in addition to custom specifiers.
This library comes in two flavors, corresponding to the following features:
-
compile-time
The set of possible custom format specifiers is defined at compilation, so invalid specifiers can be checked at compile-time. This allows the library to have the same performance as when using the standard library formatting traits.
-
runtime
The formatting method dynamically checks the format specifier at runtime for each invocation. This is a slower version, but has a lower MSRV for greater compatibility.
Documentation
Documentation is hosted on docs.rs.
Example with the compile-time
feature
use compile_time as cfmt;
use custom_formatter;
use fmt;
) => ;
}
impl_custom_format_for_datetime!;
let date_time = DateTime ;
// Expands to:
//
// match (&(date_time), &("The date time is")) {
// (arg0, arg1) => {
// ::std::println!(
// "{0}: {1}-{2}-{3} {4}:{5}:{6}.{7}",
// arg1,
// ::custom_format::custom_formatter!("%Y", arg0),
// ::custom_format::custom_formatter!("%m", arg0),
// ::custom_format::custom_formatter!("%d", arg0),
// ::custom_format::custom_formatter!("%H", arg0),
// ::custom_format::custom_formatter!("%M", arg0),
// ::custom_format::custom_formatter!("%S", arg0),
// ::custom_format::custom_formatter!("%9N", arg0)
// )
// }
// }
//
// Output: "The date time is: 1836-05-18 23:45:54.123456789"
//
println!;
// Compile-time error since "%h" is not a valid format specifier
// cfmt::println!("{0 :%h}", date_time);
Example with the runtime
feature
use ;
use fmt;
let date_time = DateTime ;
// Expands to:
//
// match (&(date_time), &("The date time is")) {
// (arg0, arg1) => {
// ::std::println!(
// "{0}: {1}-{2}-{3} {4}:{5}:{6}.{7}",
// arg1,
// ::custom_format::runtime::CustomFormatter::new("%Y", arg0),
// ::custom_format::runtime::CustomFormatter::new("%m", arg0),
// ::custom_format::runtime::CustomFormatter::new("%d", arg0),
// ::custom_format::runtime::CustomFormatter::new("%H", arg0),
// ::custom_format::runtime::CustomFormatter::new("%M", arg0),
// ::custom_format::runtime::CustomFormatter::new("%S", arg0),
// ::custom_format::runtime::CustomFormatter::new("%9N", arg0)
// )
// }
// }
//
// Output: "The date time is: 1836-05-18 23:45:54.123456789"
//
println!;
// Panic at runtime since "%h" is not a valid format specifier
// cfmt::println!("{0 :%h}", date_time);
Compiler support
Requires rustc 1.45+
for the runtime
feature and rustc 1.51+
for the compile-time
feature.
License
This project is licensed under either of
at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.