Sorry to ask a dumb question, but could somebody tell me what the following means
for ctype, (codename, name) in searched_perms:
I don't understand what's going on the parenthesis. for ctype in serached_perms: would make sense.
I realise that the answer is in the python docs somewhere but since I don't know what I'm looking for, it's difficult to find the explaination.
This is practically equivalent to
for x in search_perms:
ctype, y = x
codename, name = y
or
for x in search_perms:
ctype = x[0]
codename = x[1][0]
name = x[1][1]
i.e., it unpacks the items from search_perms as pairs, then unpacks the second item of each pair as a pair as well.
Example:
>>> d = {"ham": "yes", "spam": "no", "eggs": "please"}
>>> for k, v in d.iteritems():
... print("%s? %s" % (k, v))
...
eggs? please
ham? yes
spam? no
>>> for i, (k, v) in enumerate(d.iteritems()):
... print("question %d: %s? %s" % (i, k, v))
...
question 0: eggs? please
question 1: ham? yes
question 2: spam? no
This works because enumerate(d.iteritems()) generates pairs where each second element is again a pair:
>>> list(enumerate(d.iteritems()))
[(0, ('eggs', 'please')), (1, ('ham', 'yes')), (2, ('spam', 'no'))]
ctype, (codename, name) is the same thing as (ctype, (codename, name)). Therefore, searched_perms needs to be a sequence of things of the form (a,(b,c)), and on each loop iteration the variables ctype, codename, name will be set to a,b,c.
Your list searchedparams should looks something like this:
In [1]: L = []
In [2]: L.append(('a', ('b', 'c')))
In [3]: L.append(('d', ('e', 'f')))
In [4]: L
Out[4]: [('a', ('b', 'c')), ('d', ('e', 'f'))]
In [6]: for ctype, (codename, name) in L:
print ctype, codename, name
...:
a b c
d e f
('a', ('b', 'c')) is a tuple of 2 values, where the right value is also a tuple of two values.
It means that searched_perms is an iterable that returns two elements during iteration: the first one is ctype and the second is a tuple, composed of another two elements: (codename, name). So searched_perms looks something like this:
[[ctype1, (code1, name1)], [ctype2, (code2, name2)], ...]
The syntax for ctype, (codename, name) in searched_perms allows the extraction of all the contents in searched_perms, element by element.
