Lexer: Chaining: Leading dot throws error when previous line ends with empty function

[bioball]

This is not a huge deal, but not the behavior I was expecting. I'd like to be able to chain method calls with function callbacks together, even if the function bodies were empty. The use case is for cases like this:

doThing()
.then (@result) =>
.catch handleError

Where I'd expect this to compile into:

doThing().then((function(_this) {
  return function(account) {
    _this.account = account;
  };
})(this))["catch"](handleError);

Currently, this just throws an error: Error on line 3: unexpected .

[edgebal]

@bioball you can use parentheses to encapsulate empty functions.

oThing()
.then ( (@result) => )
.catch handleError

[bioball]

Yup, that's what I'm currently doing. It's not such much that I can't do it, it's just that this works:

doThing()
.then (@result) => undefined
.catch handleError

While this doesn't

doThing()
.then (@result) =>
.catch handleError

Adding parentheses is fine, I just expected functions with empty bodies to work the same way functions with bodies do.

[epidemian]

I just expected functions with empty bodies to work the same way functions with bodies do.

I would expect the same. Especially considering that:

foo ->
bar ->

... compiles to:

foo(function() {});
bar(function() {});

... and:

obj
.foo ->

... compiles to:

obj.foo(function() {});

Then:

obj
.foo ->
.bar ->

... should compile to:

obj.foo(function() {}).bar(function() {});

Unless i'm missing something, this seems like a bug.

[Panoplos]

I am having a similar issue with bluebird Promise code, as follows:

doSomething argument
  .then (res) ->
    console.log res
  .catch (err) ->
    console.error err

this result in the following JavaScript:

doSomething(argument).then(function(res) {
  console.log(res);
})["catch"](function(err) {
  console.error(err);
});

Which of course is not an error, technically, by why calling the function via the object lookup?

[nfour]

@Panoplos catch is a reserved word, it's for ES4 compat or something like that.
That code, however, is compiling correctly is it not?

[michaelficarra]

@nfour: ES3.

[GeoffreyBooth]

Fixed by #4588.