Joshua Landau wrote:
> Unless you have a very good reason, don't do this. It's a damn pain
> when functions won't accept my custom types with equivalent
> functionality -- Python's a duck-typed language and it should behave
> like one.
In that case what's the pythonic way to deal with standard cases like this
one?
<code>
class SomeModel(object):
def __init__(self):
self.label = "this is a label attribute"
def accept(self, visitor):
visitor.visit(self)
print("visited: ", self.label)
class AbstractVisitor(object):
def visit(self, element):
pass
class ConcreteVisitorA(AbstractVisitor):
def visit(self, element):
element.label = "ConcreteVisitorA operated on this model"
class ConcreteVisitorB(AbstractVisitor):
def visit(self, element):
element.label = "ConcreteVisitorB operated on this model"
model = SomeModel()
operatorA = ConcreteVisitorA()
model.accept(operatorA)
operatorB = ConcreteVisitorB()
model.accept(operatorA)
not_a_valid_type = "foo"
model.accept(not_a_valid_type)
</python>
Rui Maciel
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