I'm quite new to Python oop. So, this class:
class Foo:
def barfunc(self, baz):
print baz
looks to me quite similar to
class Foo:
def barfunc(self, baz):
self.baz = baz
print self.baz
Output will, I think be the same, so I would like to know which is preferred and why. Maybe I miss major possible pitfalls from using one or another.
If your aim is to just print the baz once, then both are equivalent.
However, if you want to re-use baz later on in your code, then using the second one is the better approach, because you can add additional methods to access it now.
class Foo(object):
def barfunc(self, baz):
self.baz = baz
print self.baz
def barbar(self):
print self.baz
And now you can do
>>> f = Foo()
>>> f.barfunc(10)
10
>>> f.barbar()
10
One major pitfall is your terminology - neither example shows a class variable.
In the first example, baz is an argument to an instance method and baz is only available in the local scope of that method.
In the second example, baz is an argument to an instance method and is assigned to an instance attribute, self.baz, within that method. After the method has been called, self.baz will be available to all objects in the class instance.
the first example will have effect only inside the function..but the second one will have effect in the entire class..
class foo():
bar=1
def baz(self,bar):
print bar
def baz1(self,bar):
self.bar=bar
a=foo()
a.bar
#prints 1
a.baz(2)
#prints 2
a.bar
#here it prints 1 again because it is the class variable which is not affected by the baz() function's local variable
a.baz1(3)
#prints 3
a.bar
#here the class variable value changes to 3 because self.bar changes the value of bar in entire class
self is the entire instance of the class and it changes every value of the class when used that is it has a global scope or scope in the entire class.
run this example and ask if you have any doubt
(), unless you're inheriting from something.. i.e.class Foo(object):. function declaration should end with:...). Further, class name should begin with capital case.