Source code: Lib/string.py
The constants defined in this module are:
The concatenation of the ascii_lowercase and ascii_uppercase constants described below. This value is not locale-dependent.
The lowercase letters 'abcdefghijklmnopqrstuvwxyz'. This value is not locale-dependent and will not change.
The uppercase letters 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'. This value is not locale-dependent and will not change.
The string '0123456789'.
The string '0123456789abcdefABCDEF'.
The string '01234567'.
String of ASCII characters which are considered punctuation characters in the C locale.
String of ASCII characters which are considered printable. This is a combination of digits, ascii_letters, punctuation, and whitespace.
A string containing all ASCII characters that are considered whitespace. This includes the characters space, tab, linefeed, return, formfeed, and vertical tab.
The built-in string class provides the ability to do complex variable substitutions and value formatting via the format() method described in PEP 3101. The Formatter class in the string module allows you to create and customize your own string formatting behaviors using the same implementation as the built-in format() method.
The Formatter class has the following public methods:
format() is the primary API method. It takes a format string and an arbitrary set of positional and keyword arguments. format() is just a wrapper that calls vformat().
This function does the actual work of formatting. It is exposed as a separate function for cases where you want to pass in a predefined dictionary of arguments, rather than unpacking and repacking the dictionary as individual arguments using the *args and **kwargs syntax. vformat() does the work of breaking up the format string into character data and replacement fields. It calls the various methods described below.
In addition, the Formatter defines a number of methods that are intended to be replaced by subclasses:
Loop over the format_string and return an iterable of tuples (literal_text, field_name, format_spec, conversion). This is used by vformat() to break the string into either literal text, or replacement fields.
The values in the tuple conceptually represent a span of literal text followed by a single replacement field. If there is no literal text (which can happen if two replacement fields occur consecutively), then literal_text will be a zero-length string. If there is no replacement field, then the values of field_name, format_spec and conversion will be None.
Given field_name as returned by parse() (see above), convert it to an object to be formatted. Returns a tuple (obj, used_key). The default version takes strings of the form defined in PEP 3101, such as “0[name]” or “label.title”. args and kwargs are as passed in to vformat(). The return value used_key has the same meaning as the key parameter to get_value().
Retrieve a given field value. The key argument will be either an integer or a string. If it is an integer, it represents the index of the positional argument in args; if it is a string, then it represents a named argument in kwargs.
The args parameter is set to the list of positional arguments to vformat(), and the kwargs parameter is set to the dictionary of keyword arguments.
For compound field names, these functions are only called for the first component of the field name; Subsequent components are handled through normal attribute and indexing operations.
So for example, the field expression ‘0.name’ would cause get_value() to be called with a key argument of 0. The name attribute will be looked up after get_value() returns by calling the built-in getattr() function.
If the index or keyword refers to an item that does not exist, then an IndexError or KeyError should be raised.
