commit d9d3a5a816253f14ee33623662690293365013e0
parent 4f2d735803f723a8d8d6ffbbb1dd6b203f71af58
Author: Sergey M <dstftw@gmail.com>
Date: Fri, 2 Aug 2019 05:54:56 +0700
[README.md] Move code from #21939 to the right place
Diffstat:
| M | README.md | | | 66 | ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ |
1 file changed, 66 insertions(+), 0 deletions(-)
diff --git a/README.md b/README.md
@@ -1216,6 +1216,72 @@ Incorrect:
'PLMYEtVRpaqY00V9W81Cwmzp6N6vZqfUKD4'
```
+### Inline values
+
+Extracting variables is acceptable for reducing code duplication and improving readability of complex expressions. However, you should avoid extracting variables used only once and moving them to opposite parts of the extractor file, which makes reading the linear flow difficult.
+
+#### Example
+
+Correct:
+
+```python
+title = self._html_search_regex(r'<title>([^<]+)</title>', webpage, 'title')
+```
+
+Incorrect:
+
+```python
+TITLE_RE = r'<title>([^<]+)</title>'
+# ...some lines of code...
+title = self._html_search_regex(TITLE_RE, webpage, 'title')
+```
+
+### Collapse fallbacks
+
+Multiple fallback values can quickly become unwieldy. Collapse multiple fallback values into a single expression via a list of patterns.
+
+#### Example
+
+Good:
+
+```python
+description = self._html_search_meta(
+ ['og:description', 'description', 'twitter:description'],
+ webpage, 'description', default=None)
+```
+
+Unwieldy:
+
+```python
+description = (
+ self._og_search_description(webpage, default=None)
+ or self._html_search_meta('description', webpage, default=None)
+ or self._html_search_meta('twitter:description', webpage, default=None))
+```
+
+Methods supporting list of patterns are: `_search_regex`, `_html_search_regex`, `_og_search_property`, `_html_search_meta`.
+
+### Trailing parentheses
+
+Always move trailing parentheses after the last argument.
+
+#### Example
+
+Correct:
+
+```python
+ lambda x: x['ResultSet']['Result'][0]['VideoUrlSet']['VideoUrl'],
+ list)
+```
+
+Incorrect:
+
+```python
+ lambda x: x['ResultSet']['Result'][0]['VideoUrlSet']['VideoUrl'],
+ list,
+)
+```
+
### Use convenience conversion and parsing functions
Wrap all extracted numeric data into safe functions from [`youtube_dl/utils.py`](https://github.com/ytdl-org/youtube-dl/blob/master/youtube_dl/utils.py): `int_or_none`, `float_or_none`. Use them for string to number conversions as well.
