Re: [PATCH] Permit user to select keys when using sdiff merge

[Chuck Swiger]

Paul Eggert wrote:
> Chuck Swiger <address@hidden> writes: 
> > http://www.pkix.net/~chuck/sdiff2.diff
>
> Sorry, I don't get the point of that proposed change.
> Why is it needed?

Not everyone speaks English as their native language, Paul.  Someone who 
speaks French might find "g" and "d" more intuitive ("gauche" and "droite"), 
for example.

English speakers might prefer "1" and "2" over "l" and "r", since that allows 
one to use the left hand to type them (and "q" or "e" as needed), while using 
their right hand to hit return after each section of a file has been merged. 
It also makes sdiff feel somewhat more like the comm program.

FreeBSD users happen to use sdiff's merge mode extensively during system 
updates while running a tool called "mergemaster".  A feature request was made 
about changing the merge behavior in the following thread:

http://lists.freebsd.org/pipermail/freebsd-current/2004-August/036062.html

When you run sdiff over a few hundred files to merge changes to /etc every 
month or so per machine one manages, being able to choose which keys to use 
makes users happier.  A fair number of FreeBSD users have wanted to see a 
change like this for a while, as one might gather from the various opinions 
which appear in that thread.

> Why should it be an environment variable rather than a new option?

Which keys a user wants to use is a preference which is unlikely to change 
from one run of sdiff to another.  I chose to implement using an environment 
variable for much the same reason that many programs pay attention to $PAGER, 
even if they don't provide a command-line option to select a pager.

On the other hand, I don't see any reason why the functionality could not be 
exposed via a CLI flag in addition, if that pleases you.

> Also, any such change would need documentation....

Sure, if you run "sdiff -o" and ask, one gets:

%help
l or 1: use the left version
r or 2: use the right version
e 1:    edit then use the left version
e 2:    edit then use the right version
e b:    edit then use the left and right versions concatenated
e:      edit a new version
s:      silently include common lines
v:      verbosely include common lines
q:      quit

If you're referring to other documentation like manpages or info docs, I 
haven't been able to locate much about sdiff's merge mode in the existing docs...?

--
-Chuck