Pymethods

Pymethods is a common name used in the CPython C API to refer to the array of PyMethodDef structures that defines module-level functions exposed to Python from a C extension. It is not a Python language feature, but a convention used by developers to register callable methods with a module.

A PyMethodDef structure describes a single function and its behavior. Its fields include the function name (ml_name), a pointer to the C implementation (ml_meth), flags indicating how arguments are passed (ml_flags), and documentation (ml_doc). The ml_flags value typically encodes whether the function accepts positional arguments, keyword arguments, a single object, or no arguments, and the corresponding C function signature must match those expectations.

In practice, a module defines a static array named pymethods that lists all functions to be exported. This array ends with a sentinel entry where all fields are NULL or zero. The array is then used, in conjunction with a PyModuleDef structure, to create the module object via PyModule_Create during module initialization.

Pymethods plays a role alongside the type’s method table, tp_methods, which defines instance methods for Python type objects. While pymethods registers module-level functions, tp_methods defines methods exposed by Python classes created in C.

Overall, pymethods is a conventional, language-specific construct within CPython’s C API for wiring C implementations to Python-callable functions, enabling extensions to offer performance-critical or system-level functionality to Python code.