python - return 语句在 python 递归中不返回任何内容

Question

下面的方法在字符串中查找是否有任何 python 方法。

def there_is_a_call( string ): 
    return string.find('(') > -1

def find_and_remove_functions( string , found_functions ): 
    if not there_is_a_call( string ):
        print( found_functions )
        return found_functions
    else: 
        function_end    = string.find('(')
        function_string = string[:function_end][::-1]
        if function_string.find('.') > -1 : 
            index = function_string.find('.')
        elif function_string.find(' ') > -1: 
            index = function_string.find(' ')
        else:
            index = len(function_string) - 1 
        func_name       = function_string[ : index + 1 ][::-1] + '()'
        new_list = found_functions 
        new_list.append( func_name )
        find_and_remove_functions( string[ function_end + 1: ], found_functions )

所以我尝试看看它是否有效，然后就会发生这种情况；

>>>> a = find_and_remove_functions( 'func() and some more()' , [] )
['func()', ' more()']
>>>> print(a)
None 

为什么 return 语句不返回任何内容，而 found_functions 却被打印出来？

Answer 1

这里:

find_and_remove_functions( string[ function_end + 1: ], found_functions )

应该是

return find_and_remove_functions( string[ function_end + 1: ], found_functions )