Trait Format 

pub trait Format {
    // Required methods
    fn try_format(&self, param: &dyn FormatParam) -> Result<String, FormatError>;
    fn try_write_to(
        &self,
        sink: &mut dyn Write,
        param: &dyn FormatParam,
    ) -> Result<(), FormatError>;
    fn builder<'t>(&'t self) -> FormatBuilder<'t, 'static>;

    // Provided methods
    fn format(&self, param: &dyn FormatParam) -> String { ... }
    fn checked_format(&self, param: &dyn FormatParam) -> Option<String> { ... }
    fn write_to(&self, sink: &mut dyn Write, param: &dyn FormatParam) { ... }
}

A template string that can be formatted with runtime arguments.

Implemented for str; String, Box<str>, etc. get it through deref. See the crate documentation for the supported placeholder syntax.

These one-shot methods parse the template on every call; for a template used repeatedly, parse it once with Template::parse.

Required Methods

fn try_format(&self, param: &dyn FormatParam) -> Result<String, FormatError>

Formats param into a new String.

Errors

Returns FormatError::InvalidFormatString for a syntactically invalid template, FormatError::InsufficientParameters for a placeholder index beyond the supplied arguments, FormatError::UnsupportedFormatType when an argument does not support the requested format type, and FormatError::ExpectedUsize when a dynamic width/precision argument is not an unsigned integer.

fn try_write_to( &self, sink: &mut dyn Write, param: &dyn FormatParam, ) -> Result<(), FormatError>

Formats param into sink, appending to its current contents.

Errors

Returns the same errors as try_format, plus FormatError::WriteFailed if the sink rejects a write. Writing into a String never fails.

fn builder<'t>(&'t self) -> FormatBuilder<'t, 'static>

Starts a FormatBuilder for adding arguments one at a time.

Examples

use rtformat::Format;

assert_eq!("{} + {} = {2}".builder().arg(&1).arg(&2).arg(&3).build(), "1 + 2 = 3");

Provided Methods

fn format(&self, param: &dyn FormatParam) -> String

Formats param into a new String.

Panics

Panics if the template or the arguments are invalid. Use try_format for a fallible version.

fn checked_format(&self, param: &dyn FormatParam) -> Option<String>

Like try_format, but returns None on error.

fn write_to(&self, sink: &mut dyn Write, param: &dyn FormatParam)

Formats param into sink, appending to its current contents.

Panics

Panics if the template or the arguments are invalid, or the sink rejects a write. Use try_write_to for a fallible version.

Examples

use rtformat::Format;

let mut log = String::from("log: ");
"user {} ({})".write_to(&mut log, &("ada", 7));
assert_eq!(log, "log: user ada (7)");

Dyn Compatibility

This trait is dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl Format for str

Template implementation for string slices. String, Box<str>, etc. get it through deref.

fn try_format(&self, param: &dyn FormatParam) -> Result<String, FormatError>

fn try_write_to( &self, sink: &mut dyn Write, param: &dyn FormatParam, ) -> Result<(), FormatError>

fn builder<'t>(&'t self) -> FormatBuilder<'t, 'static>

Implementors