chainable methods with function multiinline as arguments

[francescoagati]

i have see that isn't possible having chainable methods with function multiinline as arguments.

$("a").each(
=> $(this).css()
$(this).css()
$(this).css()
).
map(=> $(this).attr("href") ).
end()

this is compiled in this

(function(){
$("a").each(function() {
return $(this).css();
}, $(this).css(), $(this).css()).map(function() {
return $(this).attr("href");
}).end();
})();

and if i use the point for close the function in this mode:

$("a").each(
=> $(this).css()
$(this).css()
$(this).css()
.
).
map(=> $(this).attr("href") ).
end()

i have this error:

ine 5: syntax error for '.'

[jashkenas]

Using the latest CoffeeScript, this compiles just fine (despite looking like a mess) -- of course, you have to indent it correctly:

$('a').each(
  =>
    $(this).css()
    $(this).css()
    $(this).css()
).map(
  => $(this).attr('href')
).end()

Compiles into:

$('a').each(function() {
  $(this).css();
  $(this).css();
  return $(this).css();
}).map(function() {
  return $(this).attr('href');
}).end();

Closing the ticket...

[weepy]

Ah so you can't use the () in this case

$('a').each()
  =>
    $(this).css()
    $(this).css()
    $(this).css()
.map() => $(this).attr('href')

=> syntax error fail

[jashkenas]

Yeah, absolutely -- if you want to chain off a function, you'll have to enclose the call with parenthesis. I don't really think that your example should be able to compile. Chaining, block syntax, and significant whitespace don't mix too well. If it could, we could end up with ambiguous looking things like this:

els.each() el =>
  funcs.each() func =>
    func.properties.select() prop =>
      prop.isActive
  .reverse()

Notice how that reverse is two blocks back.

[weepy]

right, so is it correct that because of the way whitespace works differently to python, you can only close one block per line?

[jashkenas]

No, you can close as many as you'd like.

I just think that allowing the above example to compile is asking for trouble. If you're going to call a method on something, just visually speaking, you need to attach that period to the thing that you're calling, not just a level of indentation. Looking at the example, I would have a hard time figuring out what's being reversed.