Re: Bug in directory view

[Jeff Webb <jeff webb nta-inc net>]

On 03/14/2013 04:20 PM, Kai Willadsen wrote:
> On 1 March 2013 02:08, Jeff Webb <jeff webb nta-inc net> wrote:
> > There seems to be a "bug" in meld's directory view.  If the
> > Preferences->Text Filters->"Ignore changes which insert or delete blank
> > lines" checkbox is enabled, files which differ only by blank lines show up
> > as being different in the directory view.  If you click on one of these
> > files in the directory view, the file diff shows no differences, as
> > expected.  It seems like the fix could be as simple as something like what
> > is shown in the patch below.  You may want to do something more efficient,
> > but it seems that something like this is needed here.  This fix is very
> > useful in conjunction with something like the "C++ comment" filter when you
> > are comparing different revisions of a project and want to find the files
> > that have non-comment differences.  We were trying to do this in a case
> > where someone changed a revision number comment in every file.  This fix
> > seems to work for our test case.
>
> That also won't work for unicode or mac linebreaks, so we'd need to
> establish a list of linebreaks that would be ignored in FileDiff by
> the preference (which will then break when GTK or Python changes their
> definitions, but hey).

That sounds like a good solution to me.  I was also worried that the patch I posted may slow things down for large 
directory diffs, since it is an extra step to run on each file.  Perhaps being able to enable this feature in the 
dirdiff "Filters" drop-down would be a good idea, if that is an issue.

> I'd like to fix the bug, but I don't want to encourage the idea that
> that should work. I have to admit that it never occurred to me that
> the blank line ignoring *would* propagate across to folder
> comparisons. Basically, it's only there cause our filters can't handle
> new lines.

My use case really has to do with the text filters as well, so I think the bug is legitimate in that context. 
 As you mentioned, if the filters could handle new lines, this feature wouldn't matter very much.  In my 
case, I want to see only non-comment differences between two revisions of a source tree.  Someone decided 
that putting a revision number (and change log) in every file was a good idea, so it looks like every file 
has changed between the two revisions.  With my patch applied, I can see which files have significant changes 
without having to examine every one individually.  When I examined the meld source code, I discovered that 
the underlying issue was that even though the text filters were applied, the line differences elimination 
code was not.  That's why I described the bug the way I did.  I thought it would be more clear to not mention 
the text filters, since that part seems to be working properly.

> Could I ask you to file a bug please, and I'll take a look at a more
> general patch?

Sure.  I just filed Bug 695912:

https://bugzilla.gnome.org/show_bug.cgi?id=695912

Thanks for taking the time to examine this issue.  Also, thank you for your work on meld.  My coworkers and I 
find the tool very useful.  I also love that it's written in python -- that made it easy to dive in and fix 
the issue.

-Jeff