simple_type_checking.py

simple_type_checking.py

import sys, re, ast

type_hints_re = re.compile(r'([a-zA-Z]+):\s*([a-zA-Z]+)')

code = '''
"""x: int"""
x = 2
'''

node = ast.parse(code)

class AssignVisitor(ast.NodeVisitor):
    def __init__(self):
        self.types = {}

    def visit_Str(self, node):
        # parse node.s
        matcher = type_hints_re.search(node.s)
        name = matcher.group(1)
        tpe = matcher.group(2)
        self.types[name] = getattr(sys.modules['builtins'], tpe)

    def visit_Assign(self, node):
        target = node.targets[0]
        value = node.value
        t = self.types[target.id]
        if not (hasattr(value, 'n') and isinstance(value.n, t)):
            raise TypeError('type...XD')

AssignVisitor().visit(node)