That's right, folks, Haml is deprecating one of its commands: the
(apparently little-known) "~". Once useful for allowing people to create
whitespace-sensitive blocks of text inline, and styliciously handling
<textarea> and <pre> tags, "~" is now more or less rendered redundant
with the introduction of filters
(http://groups.google.com/group/haml/browse_thread/thread/5ed706013a47a483)
and a clever use of helper functions.
"~" had two different functions. First, it could be used as an
alternative to "=" that would replace all newlines in
whitespace-sensitive tags such as <pre> and <textarea> with the HTML
characters for newlines, thus preserving both whitespace /and/ style.
This function can now be done literally with a function:
find_and_preserve. For example, what was once:
~ text_area :user, :profile
becomes
= find_and_preserve(text_area :user, :profile)
There's also another, related helper function, just called "preserve",
that removes all newlines period, without regard for what tag is where.
The second function was to precede a nested block of text, which would
ensure that all whitespace in that text was preserved. The idea of doing
stuff with nested blocks of text might sound a lot like filters to
you... and it does to us, too, which is why we're replacing that
function with an actual filter. The "preserve" filter serves the same
purpose as the "~" on its own. For instance, what was
%pre
~
1
2
3
4
is now
%pre
:preserve
1
2
3
4
The "~" command will still be around, although undocumented, as of the
next release of Haml (1.5). If you use it, Haml will spit out a warning,
but it will work. However, in the release after 1.5, it will be gone for
good, so update your views as soon as possible.
You may be wondering why we're deprecating this at all. "Sure, Nathan,
it's like a filter," you say, "but is it really worth it to get rid of
it altogether?" Well, if you were to ask this, I would reply that yes,
yes it is worth it. There are several reasons to get rid of this:
1. It cluttered up the code. Checking for preserved text necessitated
more than its fair share of logic precisely where we wanted the
least logic. When we do eventually remove it, the code will become
much neater.
2. It was redundant. Everything it did could, and probably should,
have been done with filters or helpers.
3. It cluttered up Haml. Haml aims to be simple and easy to learn,
and having lots of obscure commands doesn't help that at all. This
is particularly true when the commands intuitively seem like they
should be something other than commands (see point 2).
We don't like deprecating stuff, and this is probably the only thing
we'll be deprecating in a good while, so don't worry about your views
breaking beyond this (if you use this... how many of you folks even knew
this command existed?).
- Nathan
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