Nearly all modern regular expression engines support numbered capturing groups and numbered backreferences. Long regular expressions with lots of groups and backreferences may be hard to read. They can be particularly difficult to maintain as adding or removing a capturing group in the middle of the regex upsets the numbers of all the groups that follow the added or removed group.

Python's re module was the first to offer a solution: named capturing groups and named backreferences.

(?P<name>group)

captures the match of group into the backreference "name". name must be an alphanumeric sequence starting with a letter. group can be any regular expression. You can reference the contents of the group with the named backreference

(?P=name)

. The question mark, P, angle brackets, and equals signs are all part of the syntax. Though the syntax for the named backreference uses parentheses, it's just a backreference that doesn't do any capturing or grouping.

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2018-06-23

Cuauhtemoc

django apps in subfolder

Given a sub-directory named "apps" for all django applications, the following steps are used to setup the sub-directory and create apps.

1 create app sub folder - "apps"

mkdir apps
touch apps/__init__.py

2 add app to sub folder:

...

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django apps in subfolder

sample manage.py

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Example

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when you see the following message then it is safe to proceed with renaming the app.

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Fixed table names

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django create app in subdir

To create a "polls" app in the "apps" sub-directory, do the following first to make the directory (assuming you are at the root of your django project):

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Posted by Cuauhtemoc to Python Django (2018-06-23 12:33)

django url (?P<>) regex - named capture group and backreference

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