Crate runtime_fmt

A crate for string formatting using runtime format strings.

This crate provides much the same facilities as std::fmt, with the additional allowance for format strings which are not known until runtime. Possible applications include internationalization, scripting, or other customization.

Each of the standard formatting macros format_args!, format!, print!, println!, write!, and writeln! have corresponding rt_ variants. Calls which previously succeeded unconditionally now return Result, which may indicate a bad format string or arguments.

The syntax for format strings and for macro invocations is equivalent to that used by std::fmt, including support for positional and named arguments. This crate shells out to the standard library implementations for as much as possible to ensure feature parity.

Macros

rt_format	Format a value of type String with a runtime format string.
rt_format_args	The core macro for runtime formatting.
rt_print	Print to standard output with a runtime format string.
rt_println	Print to standard output with a runtime format string and trailing newline.
rt_write	Write runtime-formatted data into a buffer.
rt_writeln	Write runtime-formatted data into a buffer with a trailing newline.

Structs

FormatBuf	A buffer representing a parsed format string and arguments.
Param	A type-erased parameter, with an optional name.
PreparedFormat	A pre-checked format string, ready for values of a specific type to be formatted against it.

Enums

Error

An error during parsing or formatting.

Traits

FormatArgs

A trait for types against which formatting specifiers may be pre-checked.