Same name functions in same class - is there an elegant way to determine which to call?
Inheritance is probably the best way to do this, but since you asked specifically about decorators, I wanted to show you could do this using decorators.
You'll need to use a dictionary to store your functions by version, and then look up which version to use at runtime. Here's an example.
version_store = {}
def version(v):
def dec(f):
name = f.__qualname__
version_store[(name, v)] = f
def method(self, *args, **kwargs):
f = version_store[(name, self.version)]
return f(self, *args, **kwargs)
return method
return dec
class Product(object):
def __init__(self, version):
self.version = version
@version("1.0")
def function(self):
print("1.0")
@version("2.0")
def function(self):
print("2.0")
Product("1.0").function()
Product("2.0").function()
Could you put your Product
class into two modules, v1 and v2, then import them conditionally?
For example:
Productv1.py
class Product(object):
def function():
print('for version 1.0')
Productv2.py
class Product(object):
def function():
print('for version 2.0')
Then in your main file:
main.py
if client.version == '1.0':
from Productv1 import Product
elif client.version == '2.0':
from Productv2 import Product
else:
print(f'function not support {self.version}')
p = Product
p.function()
As another option, you could go for some factory to create your class.
Create your versioned functions (note the self
parameter). This can be done in a different module. Also, add some collection to fetch the function based on the version number.
def func_10(self):
print('for version 1.0')
def func_20(self):
print('for version 2.0')
funcs = {"1.0": func_10,
"2.0": func_20}
Add a base class that contains the static parts of your implementation and a utility class to create your instances in:
class Product:
def __init__(self, version):
self.version = version
class ProductFactory(type):
@classmethod
def get_product_class(mcs, version):
# this will return an instance right away, due to the (version) in the end
return type.__new__(mcs, "Product_{}".format(version.replace(".","")), (Product,), {"function": funcs.get(version)})(version)
# if you want to return a class object to instantiate in your code omit the (version) in the end
Using this:
p1 = ProductFactory.get_product_class("1.0")
p2 = ProductFactory.get_product_class("2.0")
print(p1.__class__.__name__) # Product_10
p1.function() # for version 1.0
print(p1.function) # <bound method func_10 of <__main__.Product_10 object at 0x0000000002A157F0>>
print(p2.__class__.__name__) # Product_20
p2.function() # for version 2.0
print(p2.function) # <bound method func_20 of <__main__.Product_20 object at 0x0000000002A15860>>