Re: [PATCH] git-gui.sh: support Tcl 8.4

On Jan 6, 2015, at 11:42, Junio C Hamano wrote:

"Kyle J. McKay" [off-list ref] writes:

quoted

Tcl 8.5 introduced an extended vsatisfies syntax that is not
supported by Tcl 8.4.

Interesting.  We discussed this exact thing just before 2.0 in

   http://thread.gmane.org/gmane.comp.version-control.git/247511/focus=248858

and nobody seems to have noticed that giving the new range notation
to vsatisfies is too new back then.

quoted

Since only Tcl 8.4 is required this presents a problem.

Indeed.

quoted

However, what we really want is just a basic version compare,
so use vcompare instead to restore compatibility with Tcl 8.4.

My Tcl is not just rusty but corroded, so help me out here.

My Tcl is barely operational, but I'll give it a shot.  :)

* Your version that compares the sign of the result looks more
  correct than $gmane/248858; was the patch proposed back then but
  did not get applied wrong?  This question is out of mere
  curiosity.

Thanks for the reference.  That patch proposed this type of change:

-	if {[package vsatisfies $::_git_version 1.6.3]} {
+	if {[package vcompare $::_git_version 1.6.3]} {

But that's wrong because vsatisfies returns a boolean but vcompare  
returns an integer (think strcmp result) so the proposed change is  
testing whether the version is not 1.6.3 rather than being 1.6.3 or  
greater.  But Jens mentions this in $gmane/249491 (that the original  
patch was missing the ">= 0" part).

I can't find anything in that thread about why vsatisfies was  
preferred over vcompare other than the obvious that the vsatisfies  
version is only a 1-character change.  And that would be more than  
enough except that Tcl 8.4 doesn't support the trailing '-' vsatisfies  
syntax.  There are complaints about this problem with git-gui [1] by  
folks who have Tcl 8.4 on their system and have upgraded to Git 2.0 or  
later.

* Would it be a good idea to update the places $gmane/248895 points
  out?  It is clearly outside the scope of this fix, but we may
  want to do so while our mind is on the "how do we check required
  version?" in a separate patch.

Makes sense to me, but my Tcl knowledge isn't up to making those  
changes as the code's a bit different.  I have to paraphrase Chris's  
message here by saying that I guess those checks are correct if not  
consistent with the others.

[1] http://stackoverflow.com/questions/24315854/git-gui-cannot-start-because-of-bad-version-number

-Kyle