[Tutor] str object is not callable

[Steven D'Aprano]

Chris Hare wrote:

> def special_match(string, search=re.compile(r'[^a-zA-Z0-9\.\ \-\#\$\*\@\!\%\^\&]').search):
>         #string = string.rstrip()
>         return not bool(search(string))

The call to bool is redundant. Get rid of it. The not operator will
automatically convert its argument into a bool:

py> print('s', bool('s'), not 's')
s True False
py> print(None, bool(None), not None)
None False True


That eliminates one possible source of errors, and will be a tiny bit faster.


Also, a stylistic comment: your function as defined above is painful. Do 
yourself, and your readers, a favour by defining a named constant like this:


SPECIAL_CHARS = re.compile(r'[^a-zA-Z0-9\.\ \-\#\$\*\@\!\%\^\&]')

def special_match(string, search=SPECIAL_CHARS.search):
     return not search(string)



> However, when I use the EXACT same code in the context of the larger code,
> I get the error
> 
> return not bool(search(strg)) TypeError: 'str' object is not callable

As numerous people have already pointed out, you have shadowed either the bool
or the search functions with a variable with the same name containing a
string:


py> len("hello world")
11
py> len = 11  # oops, shadowing the builtin function
py> len("hello world")
Traceback (most recent call last):
   File "<stdin>", line 1, in <module>
TypeError: 'int' object is not callable



> As a side note -- the rstrip call is also broken, although the string
> module is imported.  I just can't figure out why this code works in one
> context and not in another.

For the same reason -- you define a local variable "string", which shadows the 
global "string" module.



-- 
Steven