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#3220: improve bytes docs a bit.

This commit is contained in:
Georg Brandl 2008-07-01 20:08:02 +00:00
parent 07a1f94fb7
commit 18da8f06eb
1 changed files with 15 additions and 12 deletions
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Doc/library/stdtypes.rst
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@ -512,17 +512,21 @@ string literals. In addition to the functionality described here, there are
also string-specific methods described in the :ref:`string-methods` section. also string-specific methods described in the :ref:`string-methods` section.
Bytes and bytearray objects contain single bytes -- the former is immutable Bytes and bytearray objects contain single bytes -- the former is immutable
while the latter is a mutable sequence. Bytes objects can be constructed from while the latter is a mutable sequence. Bytes objects can be constructed the
literals too; use a ``b`` prefix with normal string syntax: ``b'xyzzy'``. To constructor, :func:`bytes`, and from literals; use a ``b`` prefix with normal
construct byte arrays, use the :func:`bytearray` function. string syntax: ``b'xyzzy'``. To construct byte arrays, use the
:func:`bytearray` function.
.. warning:: .. warning::
While string objects are sequences of characters (represented by strings of While string objects are sequences of characters (represented by strings of
length 1), bytes and bytearray objects are sequences of *integers* (between 0 length 1), bytes and bytearray objects are sequences of *integers* (between 0
and 255), representing the ASCII value of single bytes. That means that for and 255), representing the ASCII value of single bytes. That means that for
a bytes or bytearray object *b*, ``b[0]`` will be an integer, while ``b[0:1]`` a bytes or bytearray object *b*, ``b[0]`` will be an integer, while
will be a bytes or bytearray object of length 1. ``b[0:1]`` will be a bytes or bytearray object of length 1. The
representation of bytes objects uses the literal format (``b'...'``) since it
is generally more useful than e.g. ``bytes([50, 19, 100])``. You can always
convert a bytes object into a list of integers using ``list(b)``.
Also, while in previous Python versions, byte strings and Unicode strings Also, while in previous Python versions, byte strings and Unicode strings
could be exchanged for each other rather freely (barring encoding issues), could be exchanged for each other rather freely (barring encoding issues),
@ -1413,15 +1417,14 @@ Wherever one of these methods needs to interpret the bytes as characters
The bytes and bytearray types have an additional class method: The bytes and bytearray types have an additional class method:
.. method:: bytes.fromhex(string) .. method:: bytes.fromhex(string)
bytearray.fromhex(string)
This :class:`bytes` class method returns a bytes object, decoding the given This :class:`bytes` class method returns a bytes or bytearray object,
string object. The string must contain two hexadecimal digits per byte, spaces decoding the given string object. The string must contain two hexadecimal
are ignored. digits per byte, spaces are ignored.
Example:: >>> bytes.fromhex('f0 f1f2 ')
b'\xf0\xf1\xf2'
>>> bytes.fromhex('f0 f1f2 ')
b'\xf0\xf1\xf2'
.. XXX verify/document translate() semantics! .. XXX verify/document translate() semantics!