How to sort this without 'cmp=' in python 3?

[Mike H]

On Saturday, October 15, 2016 at 12:27:42 AM UTC-7, Peter Otten wrote:
> 38016... at gmail.com wrote: 
> 
> > nums=['3','30','34','32','9','5'] 
> > I need to sort the list in order to get the largest number string: 
> > '953433230' 
> > 
> > nums.sort(cmp=lambda a,b: cmp(a+b, b+a), reverse=True) 
> > 
> > But how to do this in python 3? 
> > 
> > Thank you
> While cmp_to_key is neat doing it by hand should also be instructive. 
> Essentially you move the comparison into a method of the key: 
> 
> $ cat translate_cmp.py 
> class Key(str): 
> def __lt__(a, b): 
> return a + b < b + a 
> 
> nums = ['3','30','34','32','9','5'] 
> print(nums) 
> nums.sort(key=Key, reverse=True) 
> print(nums) 
> print("".join(nums)) 
> 
> $ python3 translate_cmp.py
> ['3', '30', '34', '32', '9', '5']
> ['9', '5', '34', '3', '32', '30']
> 953433230 
> 
> The above works because in CPython list.sort() currently uses only the < 
> operator; adding __gt__() and __eq__() to make this portable is 
> straightforward even if you do not use the functools.total_ordering class 
> decorator.
Is it possible to use lambda expression instead of defining a `Key` class? Something like `sorted(my_list, key = lambda x, y: x+y > y+x)`?