I'm new to python so I don't really know a lot in this topic.
I have a function which gets item type, I have three types: A, B and C.
My initial approach was to pass item type as string, for example:
def my_function (item_type):
if item_type == 'A': ...
But this is a bad approach, what are the alternatives? maybe class, but how to pass it to function
Rather than working with strings, use enums. For example:
from enum import Enum
class Colour(Enum):
RED = 0
GREEN = 1
BLUE = 2
If the colours need to be distinct then just make sure that the values assigned are all different.
Then you might have a function like this:
def func(colour):
match colour:
case Colour.RED:
pass
case Colour.GREEN:
pass
case Colour.BLUE:
pass
Of course, the enum might be wrapped in some other class but this should get you started
If you are checking instances of classes then you can use isinstance or check using the type function
class A:
pass
a = A()
print(isinstance(a,A)) # this is the preferred method
print(type(a) == A)
OUTPUT
True
True
If you are checking the classes themselves then you can do a straight comparison.
class A:
pass
print(A == A)
OUTPUT
True
If you are checking subclasses then you can use issubclass function
class Parent:
pass
class A(Parent):
pass
class B(Parent):
pass
print(issubclass(A, Parent))
print(issubclass(B, Parent))
OUTPUT
True
True
Update from the question in your comment if you want to consolidate classes you could do something like this:
class Color:
def __init__(self, color):
self.color = color
red = Color('red')
blue = Color('blue')
green = Color('green')
print(red.color)
print(blue.color)
print(green.color)
print(isinstance(red, Color))
print(isinstance(green, Color))
OUTPUT
'red'
'blue'
'green'
True
True
The good design usually avoids using isinstance() or type() calls.
If you need some class-specific logic you better encapsulate it in a class itself. Please refer to:
https://refactoring.guru/replace-conditional-with-polymorphism
...? How does that vary depending onitem_type?