Change coding style for sql, params return lines

[Marc Tamlyn]

The current style can be quite confusing: return '%s @> %s' % (lhs, rhs), params

This is much clearer:

sql =  '{} @> {}'.format(lhs, rhs)
params = lhs_params + rhs_params
return sql, params

We should do this everywhere in the ORM or not at all.

(Originally brought up by Aymeric on ​https://github.com/django/django/pull/3219)

[José Padilla]

This seems to be already taken care of, pretty sure it can be closed.

[Marc Tamlyn]

This ticket was opened two days ago and there are no commits along those lines I can see. For example I mean places like:
​https://github.com/django/django/blob/bc46e4d4fa61eead13fe58048ae646f07d632e4f/django/db/models/lookups.py#L149-L154
​https://github.com/django/django/blob/92a17eaae081a213171b044858d6fc29df2df733/django/contrib/postgres/fields/array.py#L167-L172

There aren't that many, and several are clearer to read than the examples in that PR. The docs however suggest the current style used. It may be worth looking more generally at string manipulation in the ORM and using .format() instead of %s notation.

[Amine Zyad]

@mjtamlyn should I create a new ticket for the formatting part in the ORM ?

[Daniele Procida]

I've marked this ticket as especially suitable for people following the ​​Don't be afraid to commit tutorial at the ​PyCon Ireland 2014 sprints. If you're tackling this ticket, please don't hesitate to ask me for guidance if you'd like any, either here or on the Django IRC channels, where I can be found as EvilDMP.

[Anna Warzecha]

There are quite a lot places where %s is used in ORM string manipulation and I am not quite sure that changing to format is a good idea. It's actually not helping much with readability especially in base SQL strings defined in db/backend/schema.py. Curly braces are also used in T-SQL for escaping Date, Time and Timestamp, and in PostgreSQL for supplying Array values - this wouldn't make the issue an easy picking one IMO.
I am not really sure if changing that would have any positive outcome. I would just abandon the idea.

[Marc Tamlyn]

I am inclined to agree. Thanks for doing the detailed research.