Am 11.11.2012 23:24, schrieb Cantabile:
I'm writing a small mail library for my own use, and at the time I'm
testing parameters like this:
Let's ignore the facts that there is an existing mail library, that you
should use real parameters if they are required and that exit() is
completely inappropriate. Others explained why sufficiently.
[slightly shortened]
def function(**params)
required = ['Subject', 'From', 'To', 'msg']
for i in required:
if not i in params.keys():
print "Error, \'%s\' argument is missing" %i
Let's start with the last line: If you use "Error, missing {!r}
argument".format(i), you get the quotes automatically, plus possibly
escaped unicode characters and newlines, although it's not necessary.
Also, I would "from __future__ import print_function" in any new code,
to ease upgrading to Python 3.
Now, concerning the test whether the required parameters are passed to
the function, you can use "if i in params", which is slightly shorter
and IMHO similarly expressive. Also, it doesn't repeatedly create a
list, checks for a single element inside that list and then throws the
list away again. Further, you don't even need a list for the parameters,
since order doesn't matter and duplicates shouldn't exist, so I would
use a set instead:
required = {'Subject', 'From', 'To', 'msg'}
The advantage is slightly faster lookup (completely irrelevant for this
small number of elements) but also that it makes the intention a bit
clearer to people that know what a set is.
In a second step, you compute the intersection between the set of
required arguments and the set of supplied arguments and verify that all
are present:
if required.intersection(params.keys()) != required:
missing = required - set(params.keys())
raise Exception("missing arguments {}".format(
', '.join(missing)))
Happy hacking!
Uli
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