README.md

custom_debug

Derive Debug with a custom format per field.

Example usage

Here is a showcase of custom_debugs features:

    use custom_debug::Debug;
    use std::fmt;

    #[derive(Debug)]
    struct Foo {
        #[debug(format = "{} things")]
        x: i32,
        #[debug(skip)]
        y: i32,
        #[debug(with = hex_fmt)]
        z: i32,
        #[debug(skip_if = Option::is_none)]
        label: Option<String>,
    }

    fn hex_fmt<T: fmt::Debug>(n: &T, f: &mut fmt::Formatter) -> fmt::Result {
        write!(f, "0x{:02X?}", n)
    }

The resulting debug output would look something like this:

Foo {
    x: 42 things,
    z: 0xAB
}

Field attributes reference

Attributes within a section below are considered mutually exclusive.

Skip attributes

skip	Unconditionally skips a field.
skip_if = path::to::function	Skips a field if path::to::function(&field) returns true.

Format attributes

format = "format string {}"	Formats a field using a format string. Must contain a placeholder ({}) with modifiers of your choice.
with = path::to::formatter	Formats a field using path::to::formatter. The required signature is fn(&T, &mut std::fmt::Formatter) -> std::fmt::Result where T is a type compatible with the field's type (i.e. the function can be generic and coercions apply).