Class Constraint

mypy/constraints.py:71–105

A representation of a type constraint. It can be either T <: type or T :> type (T is a type variable).

class Constraint:
    """A representation of a type constraint.

    It can be either T <: type or T :> type (T is a type variable).
    """

    type_var: TypeVarId
    op = 0  # SUBTYPE_OF or SUPERTYPE_OF
    target: Type

    def __init__(self, type_var: TypeVarLikeType, op: int, target: Type) -> None:
        self.type_var = type_var.id
        self.op = op
        # TODO: should we add "assert not isinstance(target, UnpackType)"?
        # UnpackType is a synthetic type, and is never valid as a constraint target.
        self.target = target
        self.origin_type_var = type_var
        # These are additional type variables that should be solved for together with type_var.
        # TODO: A cleaner solution may be to modify the return type of infer_constraints()
        # to include these instead, but this is a rather big refactoring.
        self.extra_tvars: list[TypeVarLikeType] = []

    def __repr__(self) -> str:
        op_str = "<:"
        if self.op == SUPERTYPE_OF:
            op_str = ":>"
        return f"{self.type_var} {op_str} {self.target}"

    def __hash__(self) -> int:
        return hash((self.type_var, self.op, self.target))

    def __eq__(self, other: object) -> bool:
        if not isinstance(other, Constraint):
            return False
        return (self.type_var, self.op, self.target) == (other.type_var, other.op, other.target)


def infer_constraints_for_callable(