Add trailing commas to argument and parameter lists.

Add trailing commas to argument and parameter lists.

R=eernst@google.com

Committed: https://github.com/dart-lang/sdk/commit/4f9645c406cbb5a8b02c948e4c89d2dd0c4305de

[Lasse Reichstein Nielsen, 2016-06-13 08:58:22]

lrn@google.com changed reviewers:
+ eernst@google.com, floitsch@google.com

[eernst, 2016-06-14 09:08:33]

I think we should centralize the treatment of the trailing comma for derived
usage in the spec (e.g., specifying evaluation of an argument list and such).
Otherwise there are a number of additional locations where small fixes would be
needed.

https://codereview.chromium.org/2060163002/diff/1/docs/language/dartLangSpec.tex
File docs/language/dartLangSpec.tex (right):

https://codereview.chromium.org/2060163002/diff/1/docs/language/dartLangSpec....
docs/language/dartLangSpec.tex:3619: expressionList (`,' namedArgument)*
I think we should gather all the changes motivated by "this is a comment, and it
is not a TODO, so we just delete it" in a separate CL, such that we have a
reasonably easy target to search for those parts in case we do want to browse
them.

In that case, we should just leave them as they are now in this CL.

https://codereview.chromium.org/2060163002/diff/1/docs/language/dartLangSpec....
docs/language/dartLangSpec.tex:3632: (ignoring any trailing comma) proceeds as
follows:
The given argument list serves as the basis for specifying the semantics, i.e.,
it is intended to be a template for all possible argument lists (rather than,
say, an example).

In order to uphold this interpretation, I think it might be better to say
'(omitting any trailing comma)', because we avoid giving the reader the
impression that anything is imprecise here because we 'ignore' some details.

But I think it would be better to say once and for all at the location where the
grammar introduces the trailing commas (at line 694 and 3626) that _all_
argument/parameter lists in the specification will use the form where no
trailing comma is present, and the addition of a trailing comma does not have
any effect on the semantics of the given construct.

The same issue would come up with 'Type of a Function' and a number of other
places, so we had better make sure it is handled collectively (and surely we
wouldn't want to make such a comma semantically significant anywhere).

https://codereview.chromium.org/2060163002/diff/1/docs/language/dartLangSpec....
docs/language/dartLangSpec.tex:3648: An evaluated actual argument list $o_1
\ldots o_{m+l}$ derived from an actual argument list of the form $(a_1, \ldots,
a_m, q_1: a_{m+1}, \ldots, q_l: a_{m+l})$ (ignoring any trailing comma) is bound
to the formal parameters of $f$ as follows:
Same issue as line 3632.

[Lasse Reichstein Nielsen, 2016-06-27 12:21:20]

On 2016/06/14 09:08:33, eernst wrote:
> I think we should centralize the treatment of the trailing comma for derived
> usage in the spec (e.g., specifying evaluation of an argument list and such).
> Otherwise there are a number of additional locations where small fixes would
be
> needed.

Preferably we should introduce an abstract syntax separate from the concrete
syntax. The we define a mapping from concrete syntax to (simpler) abstract
syntax, and define the semantics on top of the abstract syntax.


Anyway: PTAL

[eernst, 2016-06-27 12:47:06]

LGTM

https://codereview.chromium.org/2060163002/diff/20001/docs/language/dartLangS...
File docs/language/dartLangSpec.tex (right):

https://codereview.chromium.org/2060163002/diff/20001/docs/language/dartLangS...
docs/language/dartLangSpec.tex:691: Formal parameter lists allow an optional
trailing comma after the last parameter ($`,'?$). A parameter list with such a
trailing comma is equivalent in all ways to one without the trailing comma. All
parameter lists in this specification are shown without a trailing comma, but
the rules and semantics apply equally to a parameter list with a trailing comma.
'to one without' --> 'to the same parameter list without'
just so they won't be allowed to choose freely among all argument lists.
'apply equally to ..' --> 'apply equally to the corresponding parameter list
with a trailing comma'.

https://codereview.chromium.org/2060163002/diff/20001/docs/language/dartLangS...
docs/language/dartLangSpec.tex:3632: 
Same changes: 'to the same parameter list without a trailing comma' and 'apply
equally to the corresponding parameter list with a trailing comma.'

[Lasse Reichstein Nielsen, 2016-06-27 17:27:53]

https://codereview.chromium.org/2060163002/diff/1/docs/language/dartLangSpec.tex
File docs/language/dartLangSpec.tex (right):

https://codereview.chromium.org/2060163002/diff/1/docs/language/dartLangSpec....
docs/language/dartLangSpec.tex:3619: expressionList (`,' namedArgument)*
Let's do that. Reinserted for now.

[Lasse Reichstein Nielsen, 2016-07-01 10:12:36]

https://codereview.chromium.org/2060163002/diff/20001/docs/language/dartLangS...
File docs/language/dartLangSpec.tex (right):

https://codereview.chromium.org/2060163002/diff/20001/docs/language/dartLangS...
docs/language/dartLangSpec.tex:691: Formal parameter lists allow an optional
trailing comma after the last parameter ($`,'?$). A parameter list with such a
trailing comma is equivalent in all ways to one without the trailing comma. All
parameter lists in this specification are shown without a trailing comma, but
the rules and semantics apply equally to a parameter list with a trailing comma.
On 2016/06/27 12:47:06, eernst wrote:
> 'to one without' --> 'to the same parameter list without'
> just so they won't be allowed to choose freely among all argument lists.
> 'apply equally to ..' --> 'apply equally to the corresponding parameter list
> with a trailing comma'.

Done.

[Lasse Reichstein Nielsen, 2016-07-06 13:18:03]

Description was changed from

==========
Add trailing commas to argument and parameter lists.
==========

to

==========
Add trailing commas to argument and parameter lists.

R=eernst@google.com

Committed:
https://github.com/dart-lang/sdk/commit/4f9645c406cbb5a8b02c948e4c89d2dd0c4305de
==========

[Lasse Reichstein Nielsen, 2016-07-06 13:18:05]

Committed patchset #3 (id:40001) manually as
4f9645c406cbb5a8b02c948e4c89d2dd0c4305de (presubmit successful).