+1 for lists. On Wed, Dec 17, 2014 at 3:54 PM, Carl Meyer <[email protected]> wrote: > > On 12/17/2014 01:48 PM, Aymeric Augustin wrote: > > I’m about to introduce a new setting that is a sequence of things, > TEMPLATES, and I have to decide whether it will be a tuple of a list. > > > > Unfortunately Django is very inconsistent in the type of settings. In > global_settings.py: > > > > - 22 settings are tuples > > - 10 are empty, 12 aren't > > - 12 are referred to as “lists” in code comments, 1 as “tuple” > > - 6 settings are lists > > - all of them are empty > > > > Even the tutorial is inconsistent. The first two settings described are: > > > > - INSTALLED_APPS: example is a tuple > > - TEMPLATE_DIRS: example is a list > > > > It would be nice to standardize on tuples or lists — at least for new > code if it’s undesirable to change the existing code. > > > > This is purely a matter of consistency and aesthetics. Using a tuple or > a list never makes any difference in the code. > > > > While lists are less common than tuples currently, I prefer them for two > reasons: > > > > 1) All these settings are sequences of similar things. Such values are > best represented with lists, unless they have to be immutable, in which > case a tuple can be used. (tuples are both “namedtuples without names” and > “immutable lists” in Python.) > > > > 2) Lists aren’t prone to the “missing comma in single-item tuple” > problem which bites beginners and experienced pythonistas alike. Django > even has code to defend against this mistake for a handful of settings. > Search for “tuple_settings” in the source. > > I agree with your preference for lists, for the same two reasons. > > > Surprisingly, it seems that there isn’t a backwards compatibility > problem with changing the type to lists, as the following pattern still > works: > > > > # myproject/settings.py > > from django.conf.global_settings import FILE_UPLOAD_HANDLERS > > FILE_UPLOAD_HANDLERS += ('myproject.uploadhandler.FooBarUploadHandler',) > > > > Proof: > > > >>>> foo = ['abc'] > >>>> foo += ('def',) > >>>> foo > > ['abc', ‘def’] > > > > I can’t think of another circumstance it which the type of the default > value will make a difference. > > > > So… can we normalize the code and satisfy my OCD? Or should I just stop > caring and move on? ;-) > > Unfortunately `__iadd__` and `__add__` do not have the same behavior here: > > >>> foo = ['abc'] > >>> foo = foo + ('def',) > Traceback (most recent call last): > File "<stdin>", line 1, in <module> > TypeError: can only concatenate list (not "tuple") to list > > So I think there is a backwards-compatibility issue. > > Personally, I would love to decide to just bite this bullet and > normalize to lists, but I think it would need to be marked as a > backwards-incompatibility in the release notes, and it would certainly > bite people. > > Carl > > -- > You received this message because you are subscribed to the Google Groups > "Django developers (Contributions to Django itself)" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/django-developers. > To view this discussion on the web visit > https://groups.google.com/d/msgid/django-developers/5491ED93.2080506%40oddbird.net > . > For more options, visit https://groups.google.com/d/optout. >
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