Attribute Reference

All moxy attributes use the #[moxy(...)] syntax. This page is a quick reference for every available attribute.

Display — Struct Level

Attribute	Description	Example
`display(debug)`	Quote string values	`#[moxy(display(debug))]`
`display(compact)`	Values only, space-separated	`#[moxy(display(compact))]`
`display(keyvalue)`	`key=value` pairs	`#[moxy(display(keyvalue))]`
`display(map)`	Map style without type name	`#[moxy(display(map))]`
`display(json)`	JSON serialization (requires `json` feature)	`#[moxy(display(json))]`
`display(pretty)`	Multi-line output (modifier)	`#[moxy(display(pretty))]`
`display(color)`	Colored output with default theme (requires `color` feature)	`#[moxy(display(color))]`
`display(color = "theme")`	Colored output with named theme	`#[moxy(display(color = "dracula"))]`
`display(alias = "name")`	Rename the type in output	`#[moxy(display(alias = "Person"))]`
`display("fmt", exprs...)`	Custom format string	`#[moxy(display("{}", self.name))]`

Modifiers can be combined in a single attribute: #[moxy(display(debug, pretty, color))]

They can also be split across multiple #[moxy(...)] attributes — arguments are merged automatically:

#[moxy(display(debug))]
#[moxy(display(pretty))]    // equivalent to #[moxy(display(debug, pretty))]

Specifying the same option twice with different values is a compile error:

#[moxy(display(alias = "A"))]
#[moxy(display(alias = "B"))]  // error: conflicting values for `alias`

#[moxy(display(compact))]
#[moxy(display(debug))]        // error: conflicting display styles

Display — Field Level

Attribute	Description	Example
`display(skip)`	Exclude field from output	`#[moxy(display(skip))]`
`display(alias = "name")`	Rename field in output	`#[moxy(display(alias = "full_name"))]`

Build — Field Level

Attribute	Description	Example
`build`	Include field in builder (compile error if unset at build time)	`#[moxy(build)]`
`build("name")`	Include field with a custom setter method name	`#[moxy(build("username"))]`
`build(default = expr)`	Include field with a fallback value (optional in builder)	`#[moxy(build(default = 8080u16))]`
`build("name", default = expr)`	Custom setter name + default value	`#[moxy(build("port", default = 8080u16))]`

Default — Field Level

Attribute	Description	Example
`default = expr`	Use expression as field’s default value (passed through `.into()`)	`#[moxy(default = "localhost")]`

Supports literals, typed literals, constants, and arbitrary expressions:

#[moxy(default = "hello")]          // string literal
#[moxy(default = 8080u16)]          // typed literal
#[moxy(default = MAX_RETRIES)]      // constant
#[moxy(default = Vec::new())]       // expression

Get — Field Level

Attribute	Description	Example
`get`	Generate getter (returns `&Deref::Target` — e.g. `String` → `&str`. Use `copy` for primitives)	`#[moxy(get)]`
`get("name")`	Custom getter method name	`#[moxy(get("id"))]`
`get(copy)`	Return by value (for `Copy` types and primitives like `u32`, `bool`)	`#[moxy(get(copy))]`
`get(clone)`	Return by clone	`#[moxy(get(clone))]`
`get(mutable)`	Also generate `field_mut(&mut self) -> &mut T`	`#[moxy(get(mutable))]`
`get(on = expr)`	Run expression before returning	`#[moxy(get(on = log::debug!("read")))]`

Set — Field Level

Attribute	Description	Example
`set`	Generate setter (`fn set_field(&mut self, value: impl Into<T>) -> &mut Self`)	`#[moxy(set)]`
`set("name")`	Custom setter method name (replaces `set_field`)	`#[moxy(set("update_id"))]`
`set(on = expr)`	Transform: expression result is assigned (`value: T` in scope)	`#[moxy(set(on = value.to_lowercase()))]`

Deref — Field Level

Attribute	Description	Example
`deref`	Mark field as deref target (required for multi-field structs)	`#[moxy(deref)]`

Union — Variant Level

Attribute	Description	Example
`variant(alias = "name")`	Rename generated methods (`is_name`, `as_name`, `to_name`)	`#[moxy(variant(alias = "ident"))]`
`variant(skip)`	Skip all method generation for this variant	`#[moxy(variant(skip))]`

unionize! — Macro Syntax

moxy::unionize! {{
    VariantName => Type,
    ...
} as [visibility] EnumName}

Generates an enum with tuple variants, is_*/as_*/to_* methods, and From<Type> impls.

Forward — Struct Field Level

Attribute	Description	Example
`forward(fn sig, ...)`	Declare methods to forward to this field	`#[moxy(forward(fn len(&self) -> usize))]`

Forward — Enum Level

Attribute	Description	Example
`forward(fn sig, ...)`	Declare methods forwarded across all variants	`#[moxy(forward(fn area(&self) -> f64))]`

Forward — Enum Variant Level

Attribute	Description	Example
`forward(skip)`	Exclude variant from forwarding (generates `unreachable!()`)	`#[moxy(forward(skip))]`
`forward`	Mark which field to forward to in named variants (defaults to first)	`#[moxy(forward)]`

Color Themes

Theme Name	Struct Name	Fields	Values	Punctuation
`dracula` (default)	cyan	pink	yellow	white
`atom-one-dark`	gold	purple	green	gray
`github-dark`	blue	red	light blue	light gray

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