[Python-Dev] Syntax suggestion for imports (original) (raw)

Jeroen Ruigrok van der Werven asmodai at in-nomine.org
Thu Jan 3 10:08:42 CET 2008

-On [20080103 08:53], Raymond Hettinger (python at rcn.com) wrote:

Thanks. I'm more curious about the content of those lines. Does the proposed syntax help, does the need go away in Py3.0, what is the typical pattern?

These are some of the examples, I've tried to reduce them to specific use patterns:

To determine if some feature is available: try: pygments = import('pygments', {}, {}, []) have_pygments = True except ImportError: have_pygments = False

try: from docutils import nodes from docutils.core import publish_parts from docutils.parsers import rst from docutils import version except ImportError: raise TracError(_('Docutils not found')) if StrictVersion(version) < StrictVersion('0.3.9'): raise TracError(_('Docutils version >= %(version)s required, ' '%(found)s found', version='0.3.9', found=version))

To specify which specific version we have of a given module: try: import pysqlite2.dbapi2 as sqlite have_pysqlite = 2 except ImportError: try: import sqlite3 as sqlite have_pysqlite = 2 except ImportError: try: import sqlite have_pysqlite = 1 except ImportError: have_pysqlite = 0

This gets repeated a lot in order to see if we have threading: try: import threading except ImportError: import dummy_threading as threading threading._get_ident = lambda: 0

Functions we do use and need, fall-back to support code if not present: try: from operator import attrgetter, itemgetter except ImportError: def attrgetter(name): def _getattr(obj): return getattr(obj, name) return _getattr def itemgetter(name): def _getitem(obj): return obj[name] return _getitem

Masking functions if a particular function is not found: try: from base64 import b64decode except ImportError: from base64 import decodestring as b64decode

-- Jeroen Ruigrok van der Werven <asmodai(-at-)in-nomine.org> / asmodai イェルーン ラウフロック ヴァン デル ウェルヴェン http://www.in-nomine.org/ | http://www.rangaku.org/ Only I can change my life. No one can do it for me...

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