On Tue, Oct 05, 2021 at 08:45:55AM +0100, Alex Waygood wrote:
I think there definitely should be a more obvious way to do this (specifically the first and last keys/values/items of a dictionary
What's your use-case for caring what the first and last key in a dict is?
An anti-pattern you see quite often on Stack Overflow to get the first key of a dictionary is something like the following:
first_key = list(mydict.keys())
Example number 9758 of why not to trust everything you see on Stackoverflow :-)
Another possibility I've been wondering about was whether several methods should be added to the dict interface:
dict.first_key = lambda self: next(iter(self)) dict.first_val = lambda self: next(iter(self.values())) dict.first_item = lambda self: next(iter(self.items())) dict.last_key = lambda self: next(reversed(self)) dict.last_val = lambda self: next(reversed(self.values())) dict.last_item = lambda self: next(reversed(self.items()))
Not every *one* line function needs to be a builtin.
But I think I like a lot more the idea of adding general ways of doing these things to itertools.
How about some recipes? `next(iter(mydict))` etc is a simple, easy, memorable, readable, maintainable way to get what you want. Composition of simple operations is great! Not everything needs to be a named function:
def addone(x): """Return x + 1.
>>> addone(32) 33
""" return x + 1