Unicode

in python

We Cover these now

● Unicode history● terms clarity (code point,BOM,utf-8,utf-16)● decoding and encoding in python● how django handles these?● helpful python modules to tackle it

Note: BOM is used in utf-16.since, it has multi bytes character code point

How it came?

Americans came up with (7 bit)ASCII representation with english only alphabets as a standard to exchange information.(‘A’ - 65, ’a’ - 97)

Rest of the world came up with their unaccented english characters ('ä', )in their own way.(messed up)

What causes unicode born?

To exchange information in all languages, we got some requirements● Unique and simple rule was needed● Adoptable across all machines(windows,ibm,

etc..)● Efficient storage as much possible

Unicode

Unicode = UCS(universal character set) + bit representation logicUCS:character + code point(‘a’, 97)bit representation:

BOM = Big endian (or) Little endian

00 48 00 65 00 6C 00 6C 00 6F (or) 48 00 65 00 6C

00 6C 00 6F 00

utf-8 is famous, because

● multi-byte encoding● variable width encoding● upto 4 byte code points are allowed by utf-8● mostly, No need BOM(8 bits)● memory efficient

How? for NON-ASCII bytes, 1st byte is reserved to indicate the no of bytes the char is using(eg.compression)

decoding

Character to Numeric value(code point) conversion● from <type 'str'> to <type 'unicode'>● it throws maximum “UnicodeDecodeError:”

(samples demo)

encoding

● Numeric value(code point) to Characters● from <type 'unicode'> to <type 'str'>● it throws maximum “UnicodeEncodeError:”

(samples demo)

Rules to Remember…

● Decode early, Unicode everywhere, Encode late● UTF-8 is the best guess for an encoding● chardet.detect()==========================

in Python 3 this is solved…

● <type 'str'> is a Unicode object

How django handles?>>> def to_unicode(... obj, encoding='utf-8'):... if isinstance(obj, basestring):... if not isinstance(obj, unicode):... obj = unicode(obj, encoding)... return obj

smart_text(s, encoding='utf-8', strings_only=False, errors='strict')force_text(s, encoding='utf-8', strings_only=False, errors='strict')smart_bytes(s, encoding='utf-8', strings_only=False, errors='strict')

How to set your python default encoding standard?

import sys>>>reload(sys)>>>sys.setdefaultencoding(‘utf-8’)>>>sys.getdefaultencoding>>>’utf-8’(or)# -*- coding: utf-8 -*-(tell to python you saved <mod_name.py> in utf-8)

Related python modules..

● chardet.detect()● unicodedata● codecs

Thanks for your time

Post your questions.

samples demo….

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