iap@y2fun.com wrote:
Given a Python Script A which only returns an array ======== return ('a') ========
Then call A in another Python Script B with parameter list: b=[]
======== b.append(container.A()) return b ========
Then request B in browser. Guess what happened? ['a'] correct! But what if you "reload" B again and again? You will get ['a','a','a',........]
From the docs: 7.5 Function definitions Default parameter values are evaluated when the function definition is executed. This means that the expression is evaluated once, when the function is defined, and that that same ``pre-computed'' value is used for each call. This is especially important to understand when a default parameter is a mutable object, such as a list or a dictionary: if the function modifies the object (e.g. by appending an item to a list), the default value is in effect modified. This is generally not what was intended. A way around this is to use None as the default, and explicitly test for it in the body of the function, e.g.: def whats_on_the_telly(penguin=None): if penguin is None: penguin = [] penguin.append("property of the zoo") return penguin regards Max M