Class HasMethods

sklearn/utils/_param_validation.py:676–709

Constraint representing objects that expose specific methods. It is useful for parameters following a protocol and where we don't want to impose an affiliation to a specific module or class. Parameters ---------- methods : str or list of str The method(s) that the objec

class HasMethods(_Constraint):
    """Constraint representing objects that expose specific methods.

    It is useful for parameters following a protocol and where we don't want to impose
    an affiliation to a specific module or class.

    Parameters
    ----------
    methods : str or list of str
        The method(s) that the object is expected to expose.
    """

    @validate_params(
        {"methods": [str, list]},
        prefer_skip_nested_validation=True,
    )
    def __init__(self, methods):
        super().__init__()
        if isinstance(methods, str):
            methods = [methods]
        self.methods = methods

    def is_satisfied_by(self, val):
        return all(callable(getattr(val, method, None)) for method in self.methods)

    def __str__(self):
        if len(self.methods) == 1:
            methods = f"{self.methods[0]!r}"
        else:
            methods = (
                f"{', '.join([repr(m) for m in self.methods[:-1]])} and"
                f" {self.methods[-1]!r}"
            )
        return f"an object implementing {methods}"


class _IterablesNotString(_Constraint):