Dynamic method in python

Question

I'm trying to create a method in python, which accepts 1-n number of parameters, calls the same method on each and returns the result. For example;

(Note this is pseudo code, I'm just typing these methods/syntax on the fly - new to python )

def get_pid(*params):
    pidlist = []
    for param in params:
        pidlist.add(os.getpid(param))
    return pidlist

Ideally I would like to do something like

x, y = get_pid("process1", "process2")

Where I can add as many parameters as I want - and the method to be as 'pythonic' and compact as possible. I think there may be a better way than looping over the parameters and appending to a list?

Any suggestions/tips?

Your code already almost works as written, it is pidlist.append(), not .add(). — Martijn Pieters
– Martijn Pieters, Commented Oct 17, 2015 at 13:43
I come from a java background - I'm trying to get into the "python" way of thinking. Is there any way to improve on this code? I'd imagine the 4 lines can probably be changed to 1/2 lines — Alan Kavanagh
– Alan Kavanagh, Commented Oct 17, 2015 at 13:44
@Alan: that's true, you can make it more compact (via a listcomp or map or something) but please don't get in the habit of associating "pythonic" and "short". "Pythonic" doesn't mean "golfed", it means something more like "clear and straightforward". — DSM
– DSM, Commented Oct 17, 2015 at 13:48

Martijn Pieters · Accepted Answer · 2015-10-17 13:44:45Z

6

Your code already works. Your function accepts 0 or more arguments, and returns the results for each function call. There is but a minor mistake in it; you should use list.append(); there is no list.add() method.

You could use a list comprehension here to do the same work in one line:

def get_pid(*params):
    return [os.getpid(param) for param in params]

You could just inline this; make it a generator expression perhaps:

x, y = (os.getpid(param) for param in ("process1", "process2"))

You could also use the map() function for this:

x, y = map(os.getpid, ("process1", "process2"))

answered Oct 17, 2015 at 13:44

Martijn Pieters

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2 Comments

Remi Guan Over a year ago

By the way, set has the set.add() method :)

Martijn Pieters Over a year ago

@KevinGuan: sure, but that is neither here nor there when using a list. There are other Python objects that have .add methods too, but those are also not lists. :-P

dting · Accepted Answer · 2015-10-17 13:46:28Z

4

You can use yield to create a generator:

def get_pid(*params):
    for param in params:
        yield os.getpid(param)

x, y = get_pid("process1", "process2")
print(x, y)

answered Oct 17, 2015 at 13:46

dting

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