On 25 April 2017 at 03:53, Steven D'Aprano <steve@pearwood.info> wrote:
> On Tue, Apr 25, 2017 at 02:08:05AM +0100, Erik wrote:
>
>> I often find myself writing __init__ methods of the form:
>>
>> def __init__(self, foo, bar, baz, spam, ham):
>>   self.foo = foo
>>   self.bar = bar
>>   self.baz = baz
>>   self.spam = spam
>>   self.ham = ham
>>
>> This seems a little wordy and uses a lot of vertical space on the
>> screen.
>
> It does, and while both are annoying, in the grand scheme of things
> they're a very minor annoyance. After all, this is typically only an
> issue once per class, and not even every class, and vertical space is
> quite cheap. In general, the barrier for accepting new syntax is quite
> high, and "minor annoyance" generally doesn't reach it.

I suspect that with a suitably creative use of inspect.signature() you
could write a decorator for this:

@auto_attrs
def __init__(self, a, b, c):
    # Remaining init code, called with self.a, self.b and self.c set

I don't have time to experiment right now, but will try to find time
later. If nothing else, such a decorator would be a good prototype for
the proposed functionality, and may well be sufficient for the likely
use cases without needing a syntax change.

Paul

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