Attribute Macro pyo3::pyclass

Expand description

A proc macro used to expose Rust structs and fieldless enums as Python objects.

#[pyclass] can be used with the following parameters:

crate = "some::path"Path to import the pyo3 crate, if it’s not accessible at ::pyo3.
dictGives instances of this class an empty __dict__ to store custom attributes.
extends = BaseTypeUse a custom baseclass. Defaults to PyAny
freelist = NImplements a free list of size N. This can improve performance for types that are often created and deleted in quick succession. Profile your code to see whether freelist is right for you.
frozenDeclares that your pyclass is immutable. It removes the borrow checker overhead when retrieving a shared reference to the Rust struct, but disables the ability to get a mutable reference.
get_allGenerates getters for all fields of the pyclass.
mappingInform PyO3 that this class is a Mapping, and so leave its implementation of sequence C-API slots empty.
module = "module_name"Python code will see the class as being defined in this module. Defaults to builtins.
name = "python_name"Sets the name that Python sees this class as. Defaults to the name of the Rust struct.
rename_all = "renaming_rule"Applies renaming rules to every getters and setters of a struct, or every variants of an enum. Possible values are: “camelCase”, “kebab-case”, “lowercase”, “PascalCase”, “SCREAMING-KEBAB-CASE”, “SCREAMING_SNAKE_CASE”, “snake_case”, “UPPERCASE”.
sequenceInform PyO3 that this class is a Sequence, and so leave its C-API mapping length slot empty.
set_allGenerates setters for all fields of the pyclass.
subclassAllows other Python classes and #[pyclass] to inherit from this class. Enums cannot be subclassed.
text_signature = "(arg1, arg2, ...)"Sets the text signature for the Python class’ __new__ method.
unsendableRequired if your struct is not Send. Rather than using unsendable, consider implementing your struct in a threadsafe way by e.g. substituting Rc with Arc. By using unsendable, your class will panic when accessed by another thread. Also note the Python’s GC is multi-threaded and while unsendable classes will not be traversed on foreign threads to avoid UB, this can lead to memory leaks.
weakrefAllows this class to be weakly referenceable.

All of these parameters can either be passed directly on the #[pyclass(...)] annotation, or as one or more accompanying #[pyo3(...)] annotations, e.g.:

// Argument supplied directly to the `#[pyclass]` annotation.
#[pyclass(name = "SomeName", subclass)]
struct MyClass {}

// Argument supplied as a separate annotation.
#[pyo3(name = "SomeName", subclass)]
struct MyClass {}

For more on creating Python classes, see the class section of the guide.