First pass at "pub update" implementation.

First pass at "pub update" implementation.

This will create a "packages" directory next to the current
package's entrypoint and populate it with symlinks to packages
in the pub package cache. Transitive dependencies are handled.

Committed: https://code.google.com/p/dart/source/detail?r=6979

[Bob Nystrom, 2012-04-24 17:45:58]

I'm doing symlinks here because it's a quick and dirty way to get some kind of
packages directory generated that we can then use to play with "package:" on the
different Dart implementations.

Once we've got some other basic pub pieces in place (pub install), we'll circle
back around to this and add in link libraries and the "pub serve" stuff.

[nweiz, 2012-04-25 17:50:47]

lgtm

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/command_upd...
File utils/pub/command_update.dart (right):

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/command_upd...
utils/pub/command_update.dart:11: var dependencies;
These should be listed in the same order they're assigned.

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/io.dart
File utils/pub/io.dart (right):

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/io.dart#new...
utils/pub/io.dart:144: return runProcess('rm', ['-rf',
dir.path]).transform((result) => dir);
s/result/_/. That's more concise and consistent with other closures below.

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/io.dart#new...
utils/pub/io.dart:197: Future<bool> dirExists(dir) {
It bothers me that this and fileExists are separate. Is there any way to unify
them?

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/io.dart#new...
utils/pub/io.dart:235: // TODO(rnystrom): Check exit code and output?
Shouldn't runProcess be responsible for exit code checking?

I believe ln will always use an exit code to indicate failure, so output
checking shouldn't be necessary.

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/package.dart
File utils/pub/package.dart (right):

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/package.dar...
utils/pub/package.dart:49: Future<Collection<Package>> loadDependencies() {
I don't think the distinction between loadDependencies and traverseDependencies
is clear from the name. What about loadLocalDependencies and
loadTransitiveDependencies?

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/package.dar...
utils/pub/package.dart:74: for (final dependency in dependencies) {
I would write dependencies.forEach(walkPackage), but I won't push too hard on
that.

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/package.dar...
utils/pub/package.dart:91: int hashCode() => name.hashCode();
If you define hashCode, you should also define ==. Also, this should probably
include the directory.

[Bob Nystrom, 2012-04-25 22:20:29]

Thanks!

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/command_upd...
File utils/pub/command_update.dart (right):

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/command_upd...
utils/pub/command_update.dart:11: var dependencies;
On 2012/04/25 17:50:47, nweiz wrote:
> These should be listed in the same order they're assigned.

Done.

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/io.dart
File utils/pub/io.dart (right):

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/io.dart#new...
utils/pub/io.dart:144: return runProcess('rm', ['-rf',
dir.path]).transform((result) => dir);
On 2012/04/25 17:50:47, nweiz wrote:
> s/result/_/. That's more concise and consistent with other closures below.

Done.

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/io.dart#new...
utils/pub/io.dart:197: Future<bool> dirExists(dir) {
On 2012/04/25 17:50:47, nweiz wrote:
> It bothers me that this and fileExists are separate. Is there any way to unify
> them?

Leaving this for now per our discussion.

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/io.dart#new...
utils/pub/io.dart:235: // TODO(rnystrom): Check exit code and output?
On 2012/04/25 17:50:47, nweiz wrote:
> Shouldn't runProcess be responsible for exit code checking?
> 
> I believe ln will always use an exit code to indicate failure, so output
> checking shouldn't be necessary.

runProcess returns the exit code, but it doesn't test it because it doesn't
really know or care about what failure means.

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/package.dart
File utils/pub/package.dart (right):

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/package.dar...
utils/pub/package.dart:49: Future<Collection<Package>> loadDependencies() {
On 2012/04/25 17:50:47, nweiz wrote:
> I don't think the distinction between loadDependencies and
traverseDependencies
> is clear from the name. What about loadLocalDependencies and
> loadTransitiveDependencies?

"local" doesn't have the right connotation to me. It's a drag that
"dependencies" is already such a long work. I want something here that's clear
but not painfully long.

"loadImmediateDependencies" would work but is a mouthful. Maybe
"traverseAllDependencies" and leave load as-is?

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/package.dar...
utils/pub/package.dart:74: for (final dependency in dependencies) {
On 2012/04/25 17:50:47, nweiz wrote:
> I would write dependencies.forEach(walkPackage), but I won't push too hard on
> that.

Done.

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/package.dar...
utils/pub/package.dart:91: int hashCode() => name.hashCode();
On 2012/04/25 17:50:47, nweiz wrote:
> If you define hashCode, you should also define ==. Also, this should probably
> include the directory.

Leaving a TODO for now. I definitely want something more robust here but it can
probably wait until versioning and/or sources are in.

[nweiz, 2012-04-25 22:30:08]

lgtm

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/io.dart
File utils/pub/io.dart (right):

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/io.dart#new...
utils/pub/io.dart:235: // TODO(rnystrom): Check exit code and output?
On 2012/04/25 22:20:29, Bob Nystrom wrote:
> On 2012/04/25 17:50:47, nweiz wrote:
> > Shouldn't runProcess be responsible for exit code checking?
> > 
> > I believe ln will always use an exit code to indicate failure, so output
> > checking shouldn't be necessary.
> 
> runProcess returns the exit code, but it doesn't test it because it doesn't
> really know or care about what failure means.

I suppose that's reasonable.

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/package.dart
File utils/pub/package.dart (right):

https://chromiumcodereview.appspot.com/10207018/diff/11/utils/pub/package.dar...
utils/pub/package.dart:49: Future<Collection<Package>> loadDependencies() {
On 2012/04/25 22:20:29, Bob Nystrom wrote:
> On 2012/04/25 17:50:47, nweiz wrote:
> > I don't think the distinction between loadDependencies and
> traverseDependencies
> > is clear from the name. What about loadLocalDependencies and
> > loadTransitiveDependencies?
> 
> "local" doesn't have the right connotation to me. It's a drag that
> "dependencies" is already such a long work. I want something here that's clear
> but not painfully long.
> 
> "loadImmediateDependencies" would work but is a mouthful. Maybe
> "traverseAllDependencies" and leave load as-is?

I like "loadImmediateDependencies". It is verbose, but I think in this case
clarity is more important.