What is the difference between a string method and a str method in Python?

Question

String is a module, and str is a type. I found str methods, and some of str methods are the same with string.

>>>dir(str) ['__add__', '__class__', '__contains__', '__delattr__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__getitem__', '__getnewargs__', '__getslice__', '__gt__', '__hash__', '__init__', '__le__', '__len__', '__lt__', '__mod__', '__mul__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__rmod__', '__rmul__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', '_formatter_field_name_split', '_formatter_parser', 'capitalize', 'center', 'count', 'decode', 'encode', 'endswith', 'expandtabs', 'find', 'format', 'index', 'isalnum', 'isalpha', 'isdigit', 'islower', 'isspace', 'istitle', 'isupper', 'join', 'ljust', 'lower', 'lstrip', 'partition', 'replace', 'rfind', 'rindex', 'rjust', 'rpartition', 'rsplit', 'rstrip', 'split', 'splitlines', 'startswith', 'strip', 'swapcase', 'title', 'translate', 'upper', 'zfill'] >>> dir(string) ['Formatter', 'Template', '_TemplateMetaclass', '__builtins__', '__doc__', '__file__', '__name__', '__package__', '_float', '_idmap', '_idmapL', '_int', '_long', '_multimap', '_re', 'ascii_letters', 'ascii_lowercase', 'ascii_uppercase', 'atof', 'atof_error', 'atoi', 'atoi_error', 'atol', 'atol_error', 'capitalize', 'capwords', 'center', 'count', 'digits', 'expandtabs', 'find', 'hexdigits', 'index', 'index_error', 'join', 'joinfields', 'letters', 'ljust', 'lower', 'lowercase', 'lstrip', 'maketrans', 'octdigits', 'printable', 'punctuation', 'replace', 'rfind', 'rindex', 'rjust', 'rsplit', 'rstrip', 'split', 'splitfields', 'strip', 'swapcase', 'translate', 'upper', 'uppercase', 'whitespace', 'zfill'] 

What is the difference between two sets of methods? Can str or string use each other?

Answer 1

string now an obsolete module. You should always use the str object.

 >>> help(str) Help on class str in module __builtin__: class str(basestring) | str(object) -> string | | Return a nice string representation of the object. | If the argument is a string, the return value is the same object. . . >>>help(string) Help on module string: NAME string - A collection of string operations (most are no longer used). FILE /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/string.py MODULE DOCS http://docs.python.org/library/string DESCRIPTION Warning: most of the code you see here isn't normally used nowadays. Beginning with Python 1.6, many of these functions are implemented as methods on the standard string object. They used to be implemented by a built-in module called strop, but strop is now obsolete itself. 

Answer 2

When str methods were added in Python, most of the existing string module was rewritten as thin shell functions around str methods. For example, here is the source code for the bottom function in a line module:

 # convert UPPER CASE letters to lower case def lower(s): """lower(s) -> string Return a copy of the string s converted to lowercase. """ return s.lower()