Issue 3123. Catch exceptions in Source.exists()/initProperties()

Issue 3123. Catch exceptions in Source.exists()/initProperties()
http://code.google.com/p/dart/issues/detail?id=3123

R=brianwilkerson@google.com
BUG=
TEST=

Committed: https://code.google.com/p/dart/source/detail?r=7754

[Brian Wilkerson, 2012-05-18 17:02:52]

LGTM

https://chromiumcodereview.appspot.com/10389206/diff/1/compiler/java/com/goog...
File compiler/java/com/google/dart/compiler/UrlSource.java (right):

https://chromiumcodereview.appspot.com/10389206/diff/1/compiler/java/com/goog...
compiler/java/com/google/dart/compiler/UrlSource.java:1: // Copyright (c) 2011,
the Dart project authors.  Please see the AUTHORS file
nit: copyright year

https://chromiumcodereview.appspot.com/10389206/diff/1/compiler/java/com/goog...
compiler/java/com/google/dart/compiler/UrlSource.java:131: } catch (Throwable e)
{
Is there a reason for expanding this to catch all exceptions? (And for that
matter throwing more than MalformedURIException from initPropertiesEx()?) In
general, I think it's better to be more specific, but this might make sense.

Should we be fixing the state of the object if an exception is thrown, or will a
partially initialized source be good enough? (If these questions are bigger than
we need to address at this point feel free to ignore them.)

[scheglov, 2012-05-18 17:21:54]

https://chromiumcodereview.appspot.com/10389206/diff/1/compiler/java/com/goog...
File compiler/java/com/google/dart/compiler/UrlSource.java (right):

https://chromiumcodereview.appspot.com/10389206/diff/1/compiler/java/com/goog...
compiler/java/com/google/dart/compiler/UrlSource.java:1: // Copyright (c) 2011,
the Dart project authors.  Please see the AUTHORS file
On 2012/05/18 17:02:52, Brian Wilkerson wrote:
> nit: copyright year

Done.

https://chromiumcodereview.appspot.com/10389206/diff/1/compiler/java/com/goog...
compiler/java/com/google/dart/compiler/UrlSource.java:131: } catch (Throwable e)
{
On 2012/05/18 17:02:52, Brian Wilkerson wrote:
> Is there a reason for expanding this to catch all exceptions? (And for that
> matter throwing more than MalformedURIException from initPropertiesEx()?) In
> general, I think it's better to be more specific, but this might make sense.

1. There is reason to throw and catch specific exceptions if you are going to do
something interesting with them. Here we don't.

> 
> Should we be fixing the state of the object if an exception is thrown, or will
a
> partially initialized source be good enough? (If these questions are bigger
than
> we need to address at this point feel free to ignore them.)

2. I look on this situation in the following way: this Source is invalid, i.e.
if exists() tells you "false", you should not continue to work with it, all
other methods return undefined values.