Initialize a set() as argument of a function

Question

I have a recursive function, that takes a new set() as argument. This is the function:

def attributes(node, set):
    set.add(node.tag)
    if not node.istext():
        for n in node.content:
            set = set.intersection(attributes(node, set()))
    return set

but I get this error:

error -> TypeError
'set' object is not callable

can you post the way you are calling it with some sample input/ — Vivek Kalyanarangan, Nov 28 '16 at 12:47
Don't call your variable `set`, that shadows the built-in type `set`. You probably mean something like `def attributes(node,myset=set())`, but watch out for mutable function parameters (that only get initialized once). — Andras Deak -- Слава Україні, Nov 28 '16 at 12:47
Possible duplicate of [Is the list of Python reserved words and builtins available in a library?](http://stackoverflow.com/questions/22864221/is-the-list-of-python-reserved-words-and-builtins-available-in-a-library) — Kir Chou, Nov 28 '16 at 12:48
Actually a good example of why you shouldn't name variables from their type but from their function — bruno desthuilliers, Nov 28 '16 at 13:36
i call this function in another function: `def statistiche(fhtml, k1, k2): a=set() tup=(attributes(parse(fhtml), set), 5)` — gianluca gabriele, Nov 28 '16 at 14:42

score 5 · Answer 1 · answered Nov 28 '16 at 12:48

5

You are overwriting the global builtin set with your local parameter. Just change it to

def attributes(node, my_set):
    ...

answered Nov 28 '16 at 12:48

filmor

28,551
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score 0 · Answer 2 · edited Nov 30 '16 at 10:06

0

The problem is that your are using a datatype(set) reserved by Python itself and which you should not use as your variable name so change the name:

def attributes(node, the_set):
    the_set.add(node.tag)
    if not node.istext():
        for n in node.content:
            the_set = the_set.intersection(attributes(n, set()))
    return the_set

edited Nov 30 '16 at 10:06

bruno desthuilliers

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answered Nov 28 '16 at 12:52

Taufiq Rahman

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`set` is _not_ a "reserved keyword" - else the OP would get a `SyntaxError` at import time. – bruno desthuilliers Nov 28 '16 at 13:28
true but in some way it is treated like one – Taufiq Rahman Nov 28 '16 at 13:32
@gianlucagabriele of course - the line `the_set = the_set.intersection(attributes(node, the_set()))` is wrong and should be `the_set = the_set.intersection(attributes(node, set()))` – bruno desthuilliers Nov 29 '16 at 10:44
@brunodesthuilliers, ok nice but now i have another error: `maximum recursion depth exceeded in comparison` – gianluca gabriele Nov 30 '16 at 08:54
There's another typo in the code - it should actually be `the_set = the_set.intersection(attributes(n, set()))` – bruno desthuilliers Nov 30 '16 at 10:05

Initialize a set() as argument of a function

2 Answers2