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pythonlocalunbound

UnboundLocalError "local variable result referenced before assignment" with variable even though i assigned it

I am making a custom programming language. This is a method in a class in my code. When i need to return the result, the error occurs.

UnboundLocalError: local variable 'result' referenced before assignment

   def visit_BinOpNode(self, node):
        left = self.visit(node.left_node)
        right = self.visit(node.right_node)

        if node.op_tok.value == TT_PLUS:
            result = left.add_to(right)
        elif node.op_tok.value == TT_MINUS:
            result = left.sub_to(right)
        elif node.op_tok.value == TT_MUL:
            result = left.mul_to(right)
        elif node.op_tok.value == TT_DIV:
            result = left.div_to(right)

        return result.set_pos(node.pos_start, node.pos_end)

Anyone help?

Solution

  • result is not defined if none of the if statements evaluates to true, so it will error out in the last line when you try to use result. You can set a default value like result = None or something and check for that at the end, or you could use else instead of else if for the last branch.