Mercurial > pylearn
comparison doc/v2_planning/coding_style.txt @ 1150:d7192e52653e
coding_style: Moved some elements to official API
| author | Olivier Delalleau <delallea@iro> |
|---|---|
| date | Thu, 16 Sep 2010 17:00:58 -0400 |
| parents | f6011a2aff0b |
| children | 0904dd74894d |
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| 1148:2da593b0f29d | 1150:d7192e52653e |
|---|---|
| 290 Have a sample code that showcases everything one should comply to. | 290 Have a sample code that showcases everything one should comply to. |
| 291 | 291 |
| 292 Some coding guidelines (work-in-progress from OD) | 292 Some coding guidelines (work-in-progress from OD) |
| 293 ------------------------------------------------- | 293 ------------------------------------------------- |
| 294 | 294 |
| 295 * Avoid using lists if all you care about is iterating on something. Using | |
| 296 lists: | |
| 297 - uses more memory (and possibly more CPU if the code may break out of | |
| 298 the iteration) | |
| 299 - can lead to ugly code when converted to Python 3 with 2to3 | |
| 300 - can have a different behavior if evaluating elements in the list has | |
| 301 side effects (if you want these side effects, make it explicit by | |
| 302 assigning the list to some variable before iterating on it) | |
| 303 | |
| 304 Iterative version List version | |
| 305 my_dict.iterkeys() my_dict.keys() | |
| 306 my_dict.itervalues() my_dict.values() | |
| 307 my_dict.iteritems() my_dict.items() | |
| 308 itertools.imap map | |
| 309 itertools.ifilter filter | |
| 310 itertools.izip zip | |
| 311 xrange range | |
| 312 | |
| 313 * Use `in` on container objects instead of using class-specific methods. | |
| 314 It is easier to read and may allow you to use your code with different | |
| 315 container types. | |
| 316 | |
| 317 Yes No | |
| 318 --- -- | |
| 319 key in my_dict my_dict.has_key(key) | |
| 320 sub_string in my_string my_string.find(sub_string) >= 0 | |
| 321 | |
| 322 | |
| 323 * Generally prefer list comprehensions to map / filter, as the former are | |
| 324 easier to read. | |
| 325 Yes: | |
| 326 non_comments = [line.strip() for line in my_file.readlines() | |
| 327 if not line.startswith('#')] | |
| 328 No: | |
| 329 non_comments = map(str.strip, | |
| 330 filter(lambda line: not line.startswith('#'), | |
| 331 my_file.readlines())) | |
| 332 | 295 |
| 333 * Use the `key` argument instead of `cmp` when sorting (for Python 3 | 296 * Use the `key` argument instead of `cmp` when sorting (for Python 3 |
| 334 compatibility). | 297 compatibility). |
| 335 Yes: | 298 Yes: |
| 336 my_list.sort(key=abs) | 299 my_list.sort(key=abs) |