Mojo decorators

A Mojo decorator is a higher-order function that modifies or extends the behavior of a struct, a function, or some other code. Instead of actually calling the higher-order function, you simply add the decorator (such as the @fieldwise_init decorator) above your code (such as a struct). The Mojo compiler then uses the decorator function to modify your code at compile time.

No custom decorators

The creation of custom decorators is not yet supported. The available ones are built directly into the compiler.

The following pages describe each built-in decorator with examples.

📄️ @align

Specifies a minimum alignment for a struct.

📄️ @always_inline

Copies the body of a function directly into the body of the calling function.

📄️ @compiler.register

Registers a custom operation for use with the MAX Graph API.

📄️ @__copy_capture

Captures register-passable typed values by copy.

📄️ @deprecated

Mojo's `@deprecated` decorator marks outdated APIs and schedules them for removal. When used with the `use` parameter, it also provides migration suggestions.

📄️ @doc_hidden

Hides declarations from generated documentation.

📄️ @explicit_destroy

Prevents automatic destruction by a `__del__()` method and requires explicit cleanup through named destructor methods.

📄️ @export

Marks a function for export.

📄️ @fieldwise_init

Generates fieldwise constructor for a struct.

📄️ @implicit

Marks a constructor as eligible for implicit conversion.

📄️ @no_inline

Prevents a function from being inlined.

📄️ @parameter

Executes a function or if statement at compile time.

📄️ @staticmethod

Declares a struct method as static.