# methods.rs - source
Source of the Rust file `/home/runner/.cargo/registry/src/github.com-1ecc6299db9ec823/pyo3-0.13.2/src/class/methods.rs`.
Keywords: rust, rustlang, rust-lang

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    // Copyright (c) 2017-present PyO3 Project and Contributors

    use crate::{ffi, PyObject, Python};
    use std::ffi::CStr;
    use std::fmt;
    use std::os::raw::c_int;

    /// `PyMethodDefType` represents different types of Python callable objects.
    /// It is used by the `#[pymethods]` and `#[pyproto]` annotations.
    #[derive(Debug)]
    pub enum PyMethodDefType {
        /// Represents class `__new__` method
        New(PyMethodDef<ffi::newfunc>),
        /// Represents class `__call__` method
        Call(PyMethodDef<ffi::PyCFunctionWithKeywords>),
        /// Represents class method
        Class(PyMethodDef<PyMethodType>),
        /// Represents static method
        Static(PyMethodDef<PyMethodType>),
        /// Represents normal method
        Method(PyMethodDef<PyMethodType>),
        /// Represents class attribute, used by `#[attribute]`
        ClassAttribute(PyClassAttributeDef),
        /// Represents getter descriptor, used by `#[getter]`
        Getter(PyGetterDef),
        /// Represents setter descriptor, used by `#[setter]`
        Setter(PySetterDef),
    }

    #[derive(Copy, Clone, Debug)]
    pub enum PyMethodType {
        PyCFunction(ffi::PyCFunction),
        PyCFunctionWithKeywords(ffi::PyCFunctionWithKeywords),
    }

    #[derive(Clone, Debug)]
    pub struct PyMethodDef<MethodT> {
        pub(crate) ml_name: &'static CStr,
        pub(crate) ml_meth: MethodT,
        pub(crate) ml_flags: c_int,
        pub(crate) ml_doc: &'static CStr,
    }

    #[derive(Copy, Clone)]
    pub struct PyClassAttributeDef {
        pub(crate) name: &'static CStr,
        pub(crate) meth: for<'p> fn(Python<'p>) -> PyObject,
    }

    #[derive(Clone, Debug)]
    pub struct PyGetterDef {
        pub(crate) name: &'static CStr,
        pub(crate) meth: ffi::getter,
        doc: &'static CStr,
    }

    #[derive(Clone, Debug)]
    pub struct PySetterDef {
        pub(crate) name: &'static CStr,
        pub(crate) meth: ffi::setter,
        doc: &'static CStr,
    }

    // Safe because ml_meth (the T) cannot be accessed outside of the crate, so only safe-to-sync values
    // are stored in this structure.
    unsafe impl<T> Sync for PyMethodDef<T> {}

    unsafe impl Sync for ffi::PyMethodDef {}

    unsafe impl Sync for PyGetterDef {}

    unsafe impl Sync for PySetterDef {}

    unsafe impl Sync for ffi::PyGetSetDef {}

    fn get_name(name: &str) -> &CStr {
        CStr::from_bytes_with_nul(name.as_bytes())
            .expect("Method name must be terminated with NULL byte")
    }

    fn get_doc(doc: &str) -> &CStr {
        CStr::from_bytes_with_nul(doc.as_bytes()).expect("Document must be terminated with NULL byte")
    }

    impl PyMethodDef<ffi::newfunc> {
        /// Define a `__new__` function.
        pub fn new_func(name: &'static str, newfunc: ffi::newfunc, doc: &'static str) -> Self {
            Self {
                ml_name: get_name(name),
                ml_meth: newfunc,
                ml_flags: ffi::METH_VARARGS | ffi::METH_KEYWORDS,
                ml_doc: get_doc(doc),
            }
        }
    }

    impl PyMethodDef<ffi::PyCFunctionWithKeywords> {
        /// Define a `__call__` function.
        pub fn call_func(
            name: &'static str,
            callfunc: ffi::PyCFunctionWithKeywords,
            flags: c_int,
            doc: &'static str,
        ) -> Self {
            Self {
                ml_name: get_name(name),
                ml_meth: callfunc,
                ml_flags: flags | ffi::METH_VARARGS | ffi::METH_KEYWORDS,
                ml_doc: get_doc(doc),
            }
        }
    }

    impl PyMethodDef<PyMethodType> {
        /// Define a function with no `*args` and `**kwargs`.
        pub fn cfunction(name: &'static str, cfunction: ffi::PyCFunction, doc: &'static str) -> Self {
            Self {
                ml_name: get_name(name),
                ml_meth: PyMethodType::PyCFunction(cfunction),
                ml_flags: ffi::METH_NOARGS,
                ml_doc: get_doc(doc),
            }
        }

        /// Define a function that can take `*args` and `**kwargs`.
        pub fn cfunction_with_keywords(
            name: &'static str,
            cfunction: ffi::PyCFunctionWithKeywords,
            flags: c_int,
            doc: &'static str,
        ) -> Self {
            Self {
                ml_name: get_name(name),
                ml_meth: PyMethodType::PyCFunctionWithKeywords(cfunction),
                ml_flags: flags | ffi::METH_VARARGS | ffi::METH_KEYWORDS,
                ml_doc: get_doc(doc),
            }
        }

        /// Convert `PyMethodDef` to Python method definition struct `ffi::PyMethodDef`
        pub fn as_method_def(&self) -> ffi::PyMethodDef {
            let meth = match self.ml_meth {
                PyMethodType::PyCFunction(meth) => meth,
                PyMethodType::PyCFunctionWithKeywords(meth) => unsafe { std::mem::transmute(meth) },
            };

            ffi::PyMethodDef {
                ml_name: self.ml_name.as_ptr(),
                ml_meth: Some(meth),
                ml_flags: self.ml_flags,
                ml_doc: self.ml_doc.as_ptr(),
            }
        }
    }

    impl PyClassAttributeDef {
        /// Define a class attribute.
        pub fn new(name: &'static str, meth: for<'p> fn(Python<'p>) -> PyObject) -> Self {
            Self {
                name: get_name(name),
                meth,
            }
        }
    }

    // Manual implementation because `Python<'_>` does not implement `Debug` and
    // trait bounds on `fn` compiler-generated derive impls are too restrictive.
    impl fmt::Debug for PyClassAttributeDef {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            f.debug_struct("PyClassAttributeDef")
                .field("name", &self.name)
                .finish()
        }
    }

    impl PyGetterDef {
        /// Define a getter.
        pub fn new(name: &'static str, getter: ffi::getter, doc: &'static str) -> Self {
            Self {
                name: get_name(name),
                meth: getter,
                doc: get_doc(doc),
            }
        }

        /// Copy descriptor information to `ffi::PyGetSetDef`
        pub fn copy_to(&self, dst: &mut ffi::PyGetSetDef) {
            if dst.name.is_null() {
                dst.name = self.name.as_ptr() as _;
            }
            if dst.doc.is_null() {
                dst.doc = self.doc.as_ptr() as _;
            }
            dst.get = Some(self.meth);
        }
    }

    impl PySetterDef {
        /// Define a setter.
        pub fn new(name: &'static str, setter: ffi::setter, doc: &'static str) -> Self {
            Self {
                name: get_name(name),
                meth: setter,
                doc: get_doc(doc),
            }
        }

        /// Copy descriptor information to `ffi::PyGetSetDef`
        pub fn copy_to(&self, dst: &mut ffi::PyGetSetDef) {
            if dst.name.is_null() {
                dst.name = self.name.as_ptr() as _;
            }
            if dst.doc.is_null() {
                dst.doc = self.doc.as_ptr() as _;
            }
            dst.set = Some(self.meth);
        }
    }

    /// Indicates that the type `T` has some Python methods.
    pub trait PyMethods {
        /// Returns all methods that are defined for a class.
        fn py_methods() -> Vec<&'static PyMethodDefType> {
            Vec::new()
        }
    }

    /// Implementation detail. Only to be used through our proc macro code.
    /// Method storage for `#[pyclass]`.
    /// Allows arbitrary `#[pymethod]/#[pyproto]` blocks to submit their methods,
    /// which are eventually collected by `#[pyclass]`.
    #[doc(hidden)]
    #[cfg(feature = "macros")]
    pub trait PyMethodsInventory: inventory::Collect {
        /// Create a new instance
        fn new(methods: Vec<PyMethodDefType>) -> Self;

        /// Returns the methods for a single `#[pymethods] impl` block
        fn get(&'static self) -> &'static [PyMethodDefType];
    }

    /// Implemented for `#[pyclass]` in our proc macro code.
    /// Indicates that the pyclass has its own method storage.
    #[doc(hidden)]
    #[cfg(feature = "macros")]
    pub trait HasMethodsInventory {
        type Methods: PyMethodsInventory;
    }

    #[cfg(feature = "macros")]
    impl<T: HasMethodsInventory> PyMethods for T {
        fn py_methods() -> Vec<&'static PyMethodDefType> {
            inventory::iter::<T::Methods>
                .into_iter()
                .flat_map(PyMethodsInventory::get)
                .collect()
        }
    }