I am creating a word parsing class and keep getting a "bound method Word_Parser.sort_word_list of <main.Word_Parser instance at 0x1037dd3b0>" error when I run this:
class Word_Parser:
"""docstring for Word_Parser"""
def __init__(self, sentences):
self.sentences = sentences
def parser(self):
self.word_list = self.sentences.split()
def sort_word_list(self):
self.sorted_word_list = self.word_list.sort()
def num_words(self):
self.num_words = len(self.word_list)
test = Word_Parser("mary had a little lamb")
test.parser()
test.sort_word_list()
test.num_words()
print test.word_list
print test.sort_word_list
print test.num_words
This problem happens as a result of calling a method without brackets. Take a look at the example below:
class SomeClass(object):
def __init__(self):
print 'I am starting'
def some_meth(self):
print 'I am a method()'
x = SomeClass()
''' Not adding the bracket after the method call would result in method bound error '''
print x.some_meth
''' However this is how it should be called and it does solve it '''
x.some_meth()
For this thing you can use @property
as an decorator, so you could use instance methods as attributes. For example:
class Word_Parser:
def __init__(self, sentences):
self.sentences = sentences
@property
def parser(self):
self.word_list = self.sentences.split()
@property
def sort_word_list(self):
self.sorted_word_list = self.word_list.sort()
@property
def num_words(self):
self.num_words = len(self.word_list)
test = Word_Parser("mary had a little lamb")
test.parser()
test.sort_word_list()
test.num_words()
print test.word_list
print test.sort_word_list
print test.num_words
so you can use access the attributes without calling (i.e., without the ()
).
You have an instance method called num_words
, but you also have a variable called num_words
. They have the same name. When you run num_words()
, the function replaces itself with its own output, which probably isn't what you want to do. Consider return
ing your values.
To fix your problem, change def num_words
to something like def get_num_words
and your code should work fine. Also, change print test.sort_word_list
to print test.sorted_word_list
.
The syntax problem is shadowing method and variable names. In the current version sort_word_list()
is a method, and sorted_word_list
is a variable, whereas num_words
is both. Also, list.sort()
modifies the list and replaces it with a sorted version; the sorted(list)
function actually returns a new list.
But I suspect this indicates a design problem. What's the point of calls like
test.parser()
test.sort_word_list()
test.num_words()
which don't do anything? You should probably just have the methods figure out whether the appropriate counting and/or sorting has been done, and, if appropriate, do the count or sort and otherwise just return something.
E.G.,
def sort_word_list(self):
if self.sorted_word_list is not None:
self.sorted_word_list = sorted(self.word_list)
return self.sorted_word_list
(Alternately, you could use properties.)
I think you meant print test.sorted_word_list
instead of print test.sort_word_list
.
In addition list.sort()
sorts a list in place and returns None
, so you probably want to change sort_word_list()
to do the following:
self.sorted_word_list = sorted(self.word_list)
You should also consider either renaming your num_words()
function, or changing the attribute that the function assigns to, because currently you overwrite the function with an integer on the first call.
Your helpful comments led me to the following solution:
class Word_Parser:
"""docstring for Word_Parser"""
def __init__(self, sentences):
self.sentences = sentences
def parser(self):
self.word_list = self.sentences.split()
word_list = []
word_list = self.word_list
return word_list
def sort_word_list(self):
self.sorted_word_list = sorted(self.sentences.split())
sorted_word_list = self.sorted_word_list
return sorted_word_list
def get_num_words(self):
self.num_words = len(self.word_list)
num_words = self.num_words
return num_words
test = Word_Parser("mary had a little lamb")
test.parser()
test.sort_word_list()
test.get_num_words()
print test.word_list
print test.sorted_word_list
print test.num_words
and returns: ['mary', 'had', 'a', 'little', 'lamb'] ['a', 'had', 'lamb', 'little', 'mary'] 5
Thank you all.
Source: Stackoverflow.com