[platform-core-dev] Latest on path character issues

[John Arthorne <John_Arthorne@xxxxxxxxxx>]

Based on feedback from the previous
proposal, and from the experience of implementing and testing various solutions,
I have made some changes to the proposal to allow colon and backslash characters
in paths.  Essentially, the proposed solution remains similar, but
I am now proposing that we change the behaviour of the old Path constructors
to be platform-specific. This is in addition to providing the clearer new
fromOSString and fromPortableString factory methods. On platforms other
than Windows, this is a breaking change from the old behaviour of these
constructors.  

It turns out that maintaining the old
behaviour of these constructors causes even more breaking changes for existing
plugins when previously valid paths and path segments are introduced into
the platform. I.e., if one plugin migrates to the new API and starts creating
paths with colon characters, and then a string representation of that path
is handed off to a plugin that has not migrated, it will create a different
path from the string if we do not change the behaviour of the existing
constructors.

I have tested this new solution, and
I have been able to get it working with very few breaking changes to other
plugins. The most breakage was in existing test suites that created hard-coded
Windows paths such as "c:\temp\..." By contrast, when I left
the old constructors unchanged, every plugin that I encountered required
extensive migration. I believe that despite the API contract change, altering
the existing path constructors offers the best backwards compatibility
and imposes the least migration burden for downstream plugins.

I have also changed the proposal to
alter the IPath.toString representation to escape literal colon characters
in path segments. For backwards compatibility, the existing toString representation
will be left unchanged (despite being non-portable), and instead a new
toPortableString() method will be used for creating platform-independent
string representations of paths (suitable for writing to .project, .classpath,
etc).

I welcome further comments and feedback
on this latest revision of the proposal:

http://dev.eclipse.org/viewcvs/index.cgi/%7Echeckout%7E/platform-core-home/documents/path_changes.html