What is the best way to append and clear the list deriv_position = [] from inside the function test?
I got NameError: name 'deriv_position' is not defined
class TestClass:
deriv_position = []
def test():
if len(deriv_position) > 0:
print("trade is open")
deriv_position.clear()
else:
print("trade is close")
deriv_position.append("1")
test()
In python, you refer to class variables using the self keyword. So inside the function, you can pass in self and then use it...
class TestClass:
def __init__(self):
self.deriv_position = []
def test(self):
if len(self.deriv_position) > 0:
print("trade is open")
self.deriv_position.clear()
else:
print("trade is close")
self.deriv_position.append("1")
TestClass().test()
You may find it worthwhile to read up on how classes work in Python: https://docs.python.org/3/tutorial/classes.html#a-first-look-at-classes
Alternatively, if you are not using the class as a class (in your example, you are not), then there is no need for it. Just declare a global variable at the top of the file, and the test function just a function in the file.
self.deriv_position = <whatever> run in any method would create an instance variable with the same name that would shadow your class variable further on. It would be much safer to refer to it through the class, not the instance. See for example stackoverflow.com/a/25577642/550094 for more details.
test.deriv_positiontestisn't helping. And it's unclear why that's in a class at all, if you're going to call the method immediately inside the class definition.classstatement does not establish a new scope, but neither do assignments in a class statement modify the enclosing scope. The namespace created by a class statement is outside the hierarchy of scopes in Python.