12 releases
Uses old Rust 2015
0.2.4 | Feb 15, 2023 |
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0.2.3 | Feb 1, 2023 |
0.2.2 | Aug 10, 2022 |
0.2.1 | Jul 29, 2022 |
0.1.3 | May 27, 2016 |
#5 in Value formatting
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strfmt: rust library for formatting dynamic strings
This library is for rust developers who want to bring rust-like formatting to non-static strings.
Basic use of formatting Display types
extern crate strfmt;
use strfmt::strfmt;
use std::collections::HashMap;
#[test]
fn it_works() {
let mut vars = HashMap::new();
vars.insert("name".to_string(), "bob");
vars.insert("job".to_string(), "python developer");
let fmt = "hi, my name is {name} and I am a {job}!".to_string();
assert_eq!(
strfmt(&fmt, &vars).unwrap(),
"hi, my name is bob and I am a python developer!")
}
In addition to the strfmt
function, this library has the Format
trait which
adds the format
method to str
and String
types.
assert_eq!("hi, my name is {name}".format(&vars), "hi, my name is bob")
You can use this library any time you have dynamic strings you want to format, such as if you are providing your users a ui or are reading configuration files.
strfmt does not support empty identifiers (i.e. {}
or {:<10}
. Integer
identifiers will be read as str keys to the hashmap (i.e. {1:<10}
will have
key == "1")
Legacy
In the 0.2.0 update, the signature of strfmt
and Format::format
changed to
fix a bug with numeric formatting. For easy migration the strfmt_display
and
Format::format_display
function provide the old behaviour.
BETA: Formatting numeric types
This feature is in Beta and may change. I expect it to be fairly stable at this point but would appreciate feedback on development.
In addition, "signed 0 padding" (i.e. +000042) is not yet supported for numeric types
Using strfmt_map
it is also possible to format integers and floats:
let mut vars: HashMap<String, f64> = HashMap::new();
vars.insert("x".to_string(), 42.4242);
vars.insert("y".to_string(), -100.11111);
vars.insert("z".to_string(), 0.);
let f = |mut fmt: Formatter| {
fmt.f64(*vars.get(fmt.key).unwrap())
};
assert_eq!(strfmt_map("{x:<7.2}", f).unwrap(), "42.42 ");
assert_eq!(strfmt_map("{y:+.2E}", f).unwrap(), "-1.00E2");
assert_eq!(strfmt_map("{z:+.2E}", f).unwrap(), "+0.00E0");
Status and Goals
strfmt aims to support all of the formatting options defined in
std::fmt
. Currently it officially only
supports the format options for strings (beta support for i64 and f64)
See the syntax for how to create a formatted string
Current Status (in order of priority)
- get strfmt_map out of Beta and create Format.format_map method
- handle sign aware zero padding for numeric types
- format any Display type
- stabilize
strfmt_map
and addformat_map
to theFormat
trait. - add
f64
method toFormatter
allowing those usingstrfmt_map
to format f64s according to the spec - add
i64
method toFormatter
allowing those usingstrfmt_map
to format i64s according to the spec - use DisplayStr trait for formatting, permitting proper formatting of integer types.
- look for a rust library has "unbounded float" (like python) and add that to the formatter
- look for a rust library has "unbounded integer" (like python) and add that to the formatter
- Implement
vec
method toFormatter
allowing those usinstrfmt_map
to format types ofVec<Display>
in a way that uses precision and width (precision will limit the number of elements displayed, width the width of each element) - special suppport to format HashMap<String, String> for improved speed
- special suppport to format HashMap<String, &str> for improved speed
- special suppport to format HashMap<&str, &str> for improved speed
HELP
I (@vitiral) am no longer an active maintainer of this library or any rust code, but I accept pull requests that fix bugs or implement the above features. All pull requests must be tested appropriately.
Adding functionality should be fairly easy, the main piece of work is checking
and handling the flags correctly and creating comprehensive tests. Hopefully I
will be creating the f64
method soon to show how it can be done, but I could
really use all the help I can get on making this libray complete.