Opened 8 years ago

Closed 8 years ago

#26866 closed New feature (fixed)

Lazy variant of string format

Reported by: Mattias Loverot Owned by: nobody
Component: Internationalization Version: dev
Severity: Normal Keywords:
Cc: Claude Paroz Triage Stage: Ready for checkin
Has patch: yes Needs documentation: no
Needs tests: no Patch needs improvement: no
Easy pickings: no UI/UX: no

Description

I'd like to contribute with creating a lazy variant of str format method:
​https://docs.python.org/3/library/stdtypes.html#str.format

Very similar to the string_concat function:
​https://github.com/django/django/blob/master/django/utils/translation/__init__.py#L221-L227

This allows more advanced string formatting with lazy strings. My particular use case is urls.py where I don't want translators to get a chance to translate regular expressions - only the actual url piece. I ended up with:

Proposal: 

from django.utils.translation import pgettext_lazy, string_format

t = {
    'mypages': pgettext_lazy('Url', 'mypages'),
    'objects': pgettext_lazy('Url', 'objects')
}

urlpatterns = [
    url(string_format('^{mypages}/{objects}/$', **t), views.ObjectView.as_view(), name='objects')
]

With string_concat: 

    url(string_concat('^', t['mypages'], '/', t['objects'], '/$'), views.ObjectView.as_view(), name='objects')

If you accept the proposal I'll make a pull request. Thanks.

Change History (15)

comment:1 by Tim Graham, 8 years ago

Is it similar to #14174?

comment:2 by Mattias Loverot, 8 years ago

Yes, I'd say my proposed solution also covers the use case in #14174. The str.format method was very new when #14174 was created and the latest Django at that time certainly supported Python versions which did not contain str.format. Since Django nowadays requires 2.7+ I think it makes sense to implement a lazy version of string_format.

comment:3 by Tim Graham, 8 years ago

Cc: Claude Paroz added

Claude, what do you think?

comment:4 by Claude Paroz, 8 years ago

Triage Stage: Unreviewed → Accepted

Let's see how the patch looks!

comment:5 by Mattias Loverot, 8 years ago

Forked and created a ticket_26866 branch:
​https://github.com/lovmat/django/tree/ticket_26866

What do you think?

comment:6 by Claude Paroz, 8 years ago

Looks promising, tests are still missing.

comment:7 by Claude Paroz, 8 years ago

Some questions:
Should we name this function format_lazy instead?
Is django.utils.translation a better home than django.utils.text (admitting the same question could arise for string_concat)?

comment:8 by Mattias Loverot, 8 years ago

I agree django.utils.text is a better place. New attempt here:
​https://github.com/lovmat/django/tree/ticket_26866_format_lazy

I also encountered an issue with my first implementation of format_lazy - it could not handle dictionaries properly since they were forced to text immediately. E.g.:

format_lazy('{0[a]}', {'a': 'django'})

Left todo: update docs.

What do you think?

comment:9 by Claude Paroz, 8 years ago

Please make it a pull request so as we can comment on the patch.
Also please make the string_concat move/renaming to another commit, even a separate ticket/patch in my opinion.

comment:11 by Claude Paroz, 8 years ago

Has patch: set
Patch needs improvement: set

comment:12 by Claude Paroz, 8 years ago

Patch needs improvement: unset

comment:13 by Tim Graham, 8 years ago

Patch needs improvement: set

comment:14 by Tim Graham, 8 years ago

Patch needs improvement: unset
Triage Stage: Accepted → Ready for checkin

comment:15 by Claude Paroz <claude@…>, 8 years ago

Resolution: → fixed
Status: new → closed

In 9aaeec3:

Fixed #26866 -- Added format_lazy function

Added format_lazy function to django.utils.text module.
Useful when dealing with relative complex lazy string concatenations
(e.g. in urls.py when translating urls in regular expressions).

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