Create wrapper script around mojom's generate.dart in the Sky package.

Create wrapper script around mojom's generate.dart in the Sky package.

This CL does the following:
- Moves mojom's generate.dart from bin/ to lib/ to make it available for use
  by a wrapper scripts in the Sky package, thus avoiding all consumers of Sky
  needing to directly depend on mojom to be able to call
  "pub run mojom:generate".
- Adds a sky->mojom pub dependency and creates a wrapper script around mojom's
  generate.dart in the Sky package.
- Augments the Sky README to explain the usage of this script.

R=eseidel@chromium.org, sethladd@google.com

Committed: https://chromium.googlesource.com/external/mojo/+/98a4e78b2fa205d0c5065d03e293d2552e0ee098

[blundell, 2015-05-07 14:03:59]

Hi Eric,

I tested this out by deploying the Sky SDK locally and creating a package that
depended on that deployed SDK via a path dependency as well as the mojom
package. After running "pub get && pub run mojom:generate" in my test package,
its packages/ subdir had the expected contents.

[eseidel, 2015-05-07 17:55:08]

Why not make the mojo package depend on the mojom package?  Or the Sky package
depend on the mojom package?  Then users don't need to add it to their own pub
spec?

[eseidel, 2015-05-07 17:55:33]

https://codereview.chromium.org/1136503002/diff/1/sky/sdk/README.md
File sky/sdk/README.md (right):

https://codereview.chromium.org/1136503002/diff/1/sky/sdk/README.md#newcode39
sky/sdk/README.md:39: mojom: '>=0.0.3 <1.0.0'
Other than this line, the change looks fine.

[blundell, 2015-05-07 18:38:47]

https://codereview.chromium.org/1136503002/diff/1/sky/sdk/README.md
File sky/sdk/README.md (right):

https://codereview.chromium.org/1136503002/diff/1/sky/sdk/README.md#newcode39
sky/sdk/README.md:39: mojom: '>=0.0.3 <1.0.0'
On 2015/05/07 17:55:33, eseidel wrote:
> Other than this line, the change looks fine.

What you suggested was my first thought as well. Unhappily, it turns out that
dart only lets you do "pub run" on executables that are in direct dependencies.

[eseidel, 2015-05-07 18:43:38]

Maybe we should have a 2 line wrapper in Sky then?  It seems silly to have to
teach our users about this new mojom?

[blundell, 2015-05-11 14:57:21]

blundell@chromium.org changed reviewers:
+ iposva@google.com, sethladd@google.com

[blundell, 2015-05-11 14:57:21]

Hi Ivan/Seth,

What's the recommended approach here? We'd like to have consumers of Sky be able
to call mojom's generate.dart script without having to have a direct dependence
on the mojom package.

[sethladd, 2015-05-11 16:38:02]

https://codereview.chromium.org/1136503002/diff/1/sky/sdk/README.md
File sky/sdk/README.md (right):

https://codereview.chromium.org/1136503002/diff/1/sky/sdk/README.md#newcode39
sky/sdk/README.md:39: mojom: '>=0.0.3 <1.0.0'
If you want to run a Dart script from a package that is not a direct dependency,
there is one option:

1) globally install that package.

pub global activate foo

(if you then put ~/.pub-cache/bin into your PATH, you can then run those
scripts)


Meanwhile, I've opened https://code.google.com/p/dart/issues/detail?id=23426

[sethladd, 2015-05-11 16:38:55]

Can Sky depend on the mojom package?

[blundell, 2015-05-11 18:47:34]

On 2015/05/11 16:38:55, sethladd wrote:
> Can Sky depend on the mojom package?

Yes.

[blundell, 2015-05-11 18:50:10]

On 2015/05/11 18:47:34, blundell wrote:
> On 2015/05/11 16:38:55, sethladd wrote:
> > Can Sky depend on the mojom package?
> 
> Yes.

(Eric's suggestion was to create a wrapper script in Sky; it wasn't quite clear
to me how you would wrap an invocation to "pub run").

[eseidel, 2015-05-11 19:36:56]

A pub run executable which just called pub run again?  Not sure.  Presumably
there is a pub api inside dart?

[sethladd, 2015-05-11 19:42:05]

Unfortunately, pub doesn't have an API. You just interact with Pub via
command-line actions.

If Sky requires a command from the mojom package, I propose that Sky's pub
package declare a dependency on the mojom package. Then, pub run mojom:generate
will work.

I've opened https://github.com/domokit/mojo/pull/157 to help.

[blundell, 2015-05-11 19:43:27]

On 2015/05/11 19:42:05, sethladd wrote:
> Unfortunately, pub doesn't have an API. You just interact with Pub via
> command-line actions.
> 
> If Sky requires a command from the mojom package, I propose that Sky's pub
> package declare a dependency on the mojom package. Then, pub run
mojom:generate
> will work.
> 

The problem is that it's *consumers* of Sky that need to run "pub run
mojom:generate". (Apologies for the lack of context).

> I've opened https://github.com/domokit/mojo/pull/157 to help.

[sethladd, 2015-05-11 19:45:11]

On 2015/05/11 19:43:27, blundell wrote:
> On 2015/05/11 19:42:05, sethladd wrote:
> > Unfortunately, pub doesn't have an API. You just interact with Pub via
> > command-line actions.
> > 
> > If Sky requires a command from the mojom package, I propose that Sky's pub
> > package declare a dependency on the mojom package. Then, pub run
> mojom:generate
> > will work.
> > 
> 
> The problem is that it's *consumers* of Sky that need to run "pub run
> mojom:generate". (Apologies for the lack of context).
> 

If "consumers" means "a random drive-by developer that wants to build a sky
app", then we're on the same page. If not,.... then I'm confused. :/

[blundell, 2015-05-12 14:49:47]

Patchset #2 (id:20001) has been deleted

[blundell, 2015-05-12 14:56:07]

Patchset #2 (id:40001) has been deleted

[blundell, 2015-05-12 15:02:29]

Thanks for the offline discussion, Seth. It occurred to me this morning that
wrapping the invocation to "pub run mojom:generate" inside another "pub run"
invocation that's made to a sky script won't stop the wrapped invocation from
erroring out because mojom isn't a direct dependency of the consumer. So instead
I went with the approach we discussed of moving mojom's generate.dart file from
bin/ to lib/.

Eric and Ivan/Seth, PTAL.

[eseidel, 2015-05-12 15:34:38]

lgtm

[sethladd, 2015-05-12 15:49:05]

https://codereview.chromium.org/1136503002/diff/60001/sky/sdk/packages/sky/bi...
File sky/sdk/packages/sky/bin/init.dart (right):

https://codereview.chromium.org/1136503002/diff/60001/sky/sdk/packages/sky/bi...
sky/sdk/packages/sky/bin/init.dart:11: import 'dart:async';
you can remove this import

https://codereview.chromium.org/1136503002/diff/60001/sky/sdk/packages/sky/bi...
sky/sdk/packages/sky/bin/init.dart:14: main(List<String> arguments) async {
No need for async here.

https://codereview.chromium.org/1136503002/diff/60001/sky/sdk/packages/sky/bi...
sky/sdk/packages/sky/bin/init.dart:15: Process.run('dart', ['-p', 'packages',
'packages/mojom/generate.dart']);
use runSync here

https://codereview.chromium.org/1136503002/diff/60001/sky/sdk/packages/sky/bi...
sky/sdk/packages/sky/bin/init.dart:15: Process.run('dart', ['-p', 'packages',
'packages/mojom/generate.dart']);
You might want to get the result of runSync and send to stdout and stderr

ProcessResult result = Process.runSync(...);
stdout.write(result.stdout);
stdout.write(result.stderr);

[blundell, 2015-05-12 15:53:17]

https://codereview.chromium.org/1136503002/diff/60001/sky/sdk/packages/sky/bi...
File sky/sdk/packages/sky/bin/init.dart (right):

https://codereview.chromium.org/1136503002/diff/60001/sky/sdk/packages/sky/bi...
sky/sdk/packages/sky/bin/init.dart:11: import 'dart:async';
On 2015/05/12 15:49:05, sethladd wrote:
> you can remove this import

Done.

https://codereview.chromium.org/1136503002/diff/60001/sky/sdk/packages/sky/bi...
sky/sdk/packages/sky/bin/init.dart:14: main(List<String> arguments) async {
On 2015/05/12 15:49:05, sethladd wrote:
> No need for async here.

Done.

https://codereview.chromium.org/1136503002/diff/60001/sky/sdk/packages/sky/bi...
sky/sdk/packages/sky/bin/init.dart:15: Process.run('dart', ['-p', 'packages',
'packages/mojom/generate.dart']);
On 2015/05/12 15:49:04, sethladd wrote:
> use runSync here

Done.

https://codereview.chromium.org/1136503002/diff/60001/sky/sdk/packages/sky/bi...
sky/sdk/packages/sky/bin/init.dart:15: Process.run('dart', ['-p', 'packages',
'packages/mojom/generate.dart']);
On 2015/05/12 15:49:04, sethladd wrote:
> use runSync here

Done.

[sethladd, 2015-05-12 15:55:04]

lgtm! (assuming the script works :)

[blundell, 2015-05-13 09:48:54]

Committed patchset #4 (id:100001) manually as
98a4e78b2fa205d0c5065d03e293d2552e0ee098 (presubmit successful).