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PyICU 0.8.1

Python extension wrapping the ICU C++ API

Latest Version: 1.7

README file for PyICU
---------------------

Contents
--------

 - Welcome
 - Building PyICU
 - Running PyICU
 - What's available
 - API Documentation


Welcome
-------

Welcome to PyICU, a Python extension wrapping IBM's International
Components for Unicode C++ library (ICU).

PyICU is a project maintained by the Open Source Applications Foundation.

IBM's ICU homepage is: http://www-306.ibm.com/software/globalization/icu/


Building PyICU
--------------

Before building PyICU the ICU 3.6 or 3.8 libraries must be built and
installed. Refer to each system's instructions for more information.

As of version 0.5 PyICU no longer uses SWIG.

As of version 0.8 PyICU is built with distutils or setuptools:
   - verify that the INCLUDES, LFLAGS, CFLAGS and LIBRARIES dictionaries in
     setup.py contain correct values for your platform
   - python setup.py build
   - sudo python setup.py install


Running PyICU
-------------

  . Mac OS X
    Make sure that DYLD_LIBRARY_PATH contains paths to the directory(ies)
    containing the ICU libs.

  . Linux
    Make sure that LD_LIBRARY_PATH contains paths to the directory(ies)
    containing the ICU libs or that you added the corresponding -rpath
    argument to LFLAGS.

  . Windows
    Make sure that PATH contains paths to the directory(ies)
    containing the ICU DLLs.


What's available
----------------

PyICU is under active development. Currently, the string, locale, format,
calendar, timezone, charset and various iterator classes are available.
See the CHANGES file for an up to date log of changes and additions.


API Documentation
-----------------

At the moment, there is no API documentation for PyICU. The API for ICU is
documented at http://icu.sourceforge.net/apiref/icu4c/ and the following
patterns can be used to translate from the C++ APIs to the corresponding
Python APIs.

  - strings

  The ICU string type, UnicodeString, is a type pointing at a mutable
  array of UChar Unicode 16-bit wide characters. The Python unicode type
  is an immutable string of 16-bit or 32-bit wide Unicode characters.

  Because of these differences, UnicodeString and Python's unicode type
  are not merged into the same type when crossing the C++ boundary.
  ICU APIs taking UnicodeString arguments have been overloaded to also
  accept Python str or unicode type arguments. In the case of str objects,
  utf-8 encoding is assumed when converting them to UnicodeString
  objects.

  To convert a Python str encoded in a encoding other than utf-8 to an ICU
  UnicodeString use the UnicodeString(str, encodingName) constructor.

  ICU's C++ APIs accept and return UnicodeString arguments in several
  ways: by value, by pointer or by reference.
  When an ICU C++ API is documented to accept a UnicodeString & parameter,
  it is safe to assume that there are several corresponding PyICU python
  APIs making it accessible in simpler ways:
  For example, the 'UnicodeString &Locale::getDisplayName(UnicodeString &)'
  API, documented here:
      http://icu.sourceforge.net/apiref/icu4c/classLocale.html#a19
  can be invoked from Python in several ways:

    1. The ICU way

      >>> from PyICU import UnicodeString, Locale
      >>> locale = Locale('pt_BR')
      >>> string = UnicodeString()
      >>> name = locale.getDisplayName(string)
      >>> name
      
      >>> name is string
      True                  <-- string arg was returned, modified in place

    2. The Python way

      >>> from PyICU import Locale
      >>> locale = Locale('pt_BR')
      >>> name = locale.getDisplayName()
      >>> name
      

      A UnicodeString object was allocated for Python and returned.

  A UnicodeString can be coerced to a Python unicode string with Python's
  unicode() constructor. The usual len(), str(), comparison, [] and [:]
  operators are all available, with the additional twists that slicing is
  not read-only and that += is also available since a UnicodeString is
  mutable. For example:

      >>> name = locale.getDisplayName()
      
      >>> unicode(name)
      u'Portuguese (Brazil)'
      >>> len(name)
      19
      >>> str(name)           <-- works when chars fit with default encoding
      'Portuguese (Brazil)'
      >>> name[3]
      u't'
      >>> name[12:18]
      
      >>> name[12:18] = 'the country of Brasil'
      >>> name
      
      >>> name += ' oh joy'
      >>> name
      

  - error reporting

  The C++ ICU library does not use C++ exceptions to report errors. ICU
  C++ APIs return errors via a UErrorCode reference argument. All such
  APIs are wrapped by Python APIs that omit this argument and throw an
  ICUError Python exception instead. The same is true for ICU APIs taking
  both a ParseError and a UErrorCode, they are both to be omitted.

  For example, the 'UnicodeString &DateFormat::format(const Formattable &,
  UnicodeString &, UErrorCode &)' API, documented here
      http://icu.sourceforge.net/apiref/icu4c/classDateFormat.html#a6
  is invoked from Python with:

      >>> from PyICU import DateFormat, Formattable
      >>> df = DateFormat.createInstance()
      >>> df
      
      >>> f = Formattable(940284258.0, Formattable.kIsDate)
      >>> df.format(f)
      

  Of course, the simpler 'UnicodeString &DateFormat::format(UDate,
  UnicodeString &)' documented here:
      http://icu.sourceforge.net/apiref/icu4c/classDateFormat.html#a5
  can be used too:

      >>> from PyICU import DateFormat
      >>> df = DateFormat.createInstance()
      >>> df
      
      >>> df.format(940284258.0)
      

  - dates

  ICU uses a double floating point type called UDate that represents the
  number of milliseconds elapsed since 1970-jan-01 UTC for dates.

  In Python, the value returned by the time module's time() function is
  the number of seconds since 1970-jan-01 UTC. Because of this difference,
  floating point values are multiplied by 1000 when passed to APIs taking
  UDate and divided by 1000 when returned as UDate.

  Python's datetime objects, with or without timezone information, can
  also be used with APIs taking UDate arguments. The datetime objects get
  converted to UDate when crossing into the C++ layer.

  - arrays

  Many ICU API take array arguments. A list of elements of the array
  element types is to be passed from Python.

  - StringEnumeration

  An ICU StringEnumeration has three 'next' methods: next() which returns
  a 'str' objects, unext() which returns 'unicode' objects and snext()
  which returns 'UnicodeString' objects.
  Any of these methods can be used as an iterator, using the Python
  built-in 'iter' function.

  For example, let e be a StringEnumeration instance:

    [s for s in e] is a list of 'str' objects
    [s for s in iter(e.unext, None)] is a list of 'unicode' objects
    [s for s in iter(e.snext, None)] is a list of 'UnicodeString' objects

  - timezones

  The ICU TimeZone type may be wrapped with an ICUtzinfo type for usage
  with Python's datetime type. For example:

     tz = ICUtzinfo(TimeZone.createTimeZone('US/Mountain'))
     datetime.now(tz)

   or, even simpler:

     tz = ICUtzinfo.getInstance('Pacific/Fiji')
     datetime.now(tz)

  To get the default time zone use:

     defaultTZ = ICUtzinfo.getDefault()

  To get the time zone's id, use the 'tzid' attribute or coerce the time
  zone to a string:

     ICUtzinfo.getInstance('Pacific/Fiji').tzid -> 'Pacific/Fiji'
     str(ICUtzinfo.getInstance('Pacific/Fiji')) -> 'Pacific/Fiji'
 
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PyICU-0.8.1.tar.gz (md5) Source 2007-12-07 65KB
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