将Object.method（）的“ method（）”部分作为参数传递

Question

First, let me say that this is a hackerrank question which, though I could do it hackily, is allowing me to indulge my deeper python curiosities.

I would welcome comments on my general approach, but my specific question relates to the title of this post.

Question:

Task

You are given a string S. Your task is to find if string S contains, alphanumeric characters, alphabetical characters, digits, lowercase and uppercase characters.

Input Format

Single line containing, string S.

Constraints

0

Output Format

In First line, print True if S has any alphanumeric character, otherwise print False.

In Second line, print True if S has any alphabetical character, otherwise print False.

In Third line, print True if S has any digits, otherwise print False.

In Fourth line, print True if S has any lowercase character, otherwise print False.

In Fifth line, print True if S has any uppercase character, otherwise print False.

Attempted Code:

S = input()

def testing(S, fun):
    for x in S:
        if x.fun:
            print(x.fun)
            break
    else:
        print(False)

testing(S, .isalnum())
testing(S, .isalpha())
testing(S, .isdigit())
testing(S, .islower())
testing(S, .isupper())

I'm not sure how to get my string methods into my testing function in a way that lets me run them against each letter of the string(s).

I could obviously pass a kwarg and do a select-case, but that's not what I'm looking for. I'm sure there's a way to do this with lambdas (perhaps instead of passing .method() I would pass lambda x: x.method() ), but (1) I'm not too sure about lambdas, and (2) I have this theory that I'd really like to write code that a beginner can always read, and lambdas aren't beginner.

Answer 1

You can assign an instance method to a variable as if it were a normal function, by using the class name that declares the method. For instance:

fun = str.isalnum
print (fun('123'))

So your code would end up looking something like this:

def testing(S, fun):
    for x in S:
        if fun(x):
            print(fun(x))
            break
    else:
        print(False)

testing(S, str.isalnum)

or more succinctly:

def testing(S, fun):
    print(any(fun(x) for x in S))