On 2014-01-05 22:44, Philippe Sigaud wrote:
I didn't know that, thanks. I read it during the holidays in Martin
Fowler's book on DSL, but indeed that book is from 2005, IIRC.
That's a bit old :). According to this site[1] Rails 1.0 was released in
December 2005. Rails 4.0 was released in June 2013.
I think there are two reasons why they deprecated that syntax:
* They want to avoid method_missing (same as opDispatch in D)
* They want to have the name of a column close to the value of that
column. Example:
Table.find_first_by_fist_name_and_last_name("foo", "bar")
In the above example the values and the columns they belongs to are
quite disconnected. The column names are far to the right and the values
are far to the left. With the AA syntax you get the column name and its
value closely connected. It's clear to see which value belongs to which
column.
Yes, using AA is a nice idea, which avoids introducing first_name in
the current scope.
I have to admit that it looks a lot better in Ruby than in D.
Some other possibilities could be:
Table.where!(e => e.first_name == "foo").first; // Similar to std.range.filter
This is the one I like best and it's possible to have the same syntax in
Ruby as well with a plugin, Squeel[2]. This allows to have more advanced
quires containing "or" and negation.
The problem is it's basically only equality that works with this syntax.
You cannot overload !=, && or || in D. You could of course use method
names like "equals", "and" and "or".
In Squeel they "solved" it by overloading | and & to mean "or" and
"and". That causes other problems with operator precedence, one needs to
wrap everything in parentheses.
In D we would need more finer grained control of operator overloading,
like overload == separately from !=. Or, I come back to this all the
time, AST macros.
Table.where.first_name!(e => e == "foo").first;
If I look at the API in Rails I think this could cause some conflicts
with all the methods that are available on the object returned by
Table.where.
Table.where((string first_name) => first_name == "foo").first; // By
extracting the parameter name
The syntax is heavier than your example, but some nice logic can put
into a closure.
Same problem as above.
Some also advocate:
Table.where.first_name.equals("foo").first;
But I find it a bit too clunky.
Same problem as above.
[1] http://railsapps.github.io/rails-release-history.html
[2] https://github.com/activerecord-hackery/squeel
--
/Jacob Carlborg
