I'm trying to write something like:
class MyClass(object):
@staticmethod
def test(x, y, z=None):
if not z:
z = external_function(MyClass)
Is it possible in python to rewrite it to something like:
class MyClass(object):
@staticmethod
def test(x, y, z=external_function(MyClass)):
pass
(The second code does not work as it is referencing MyClass which is not defined at this point)
It is not possible to rewrite the code that way. The closest you can do is something like:
class MyClass:
pass
def test(x, y, z=external_function(MyClass):
pass
MyClass.test = staticmethod(test)
del test
Note that this assumes Python 3; in Python 2, you may need to fiddle around with the new module. But though this is possible, the intention of the code is very non-obvious. It is better to stick to if z is None, or to refactor your code to not need this.
It's not possible, since whatever is in the argument definition of any method, be it a static method or a normal method, is parsed and executed at class creation time, before the class object that you try to use has been created. Defaults are also evaluated at this time, as the code below demonstrates.
def say_hi():
print "Getting default value"
class MyClass(object):
print "Creating class"
@staticmethod
def test(a=say_hi()):
print "test called"
MyClass.test()
MyClass.test()
Output:
Creating class Getting default value test called test called
selfas their first variable. 99% of the time, you're not passing the class to an external function, you're passing the instance variable (or object),self, to the external function. What you're doing with the class as a whole, seems incorrect. Are you trying to write a@classfunction? Or are you trying to manipulate an object of the class?@staticmethod.testa classmethod, which takesclsas the first parameter, then use that in your call toexternal_function.