From: jm <jm@...>
Date: 2004-08-02T11:10:47+09:00
Subject: Re: a question on diff modules

Thanks. Two things.

1) I get the following while attempting to install Diff::LCS

Generating HTML...

                              lcs.rb: mmm......mc............
                            array.rb: c
                            block.rb: c...
                        callbacks.rb: cc...cc...c....c.....cc.
                           change.rb: c.........
                            event.rb: c.
                             hunk.rb: c............
                           string.rb: c
Generating RI...
Couldn't build Ri documentation
Unhandled special: Special: type=17, text="Computes"
install.rb:171:in `install_binfile': undefined local variable or method 
`opfile' for main:Object (NameError)
         from install.rb:25:in `do_bins'
         from install.rb:23:in `each'
         from install.rb:23:in `do_bins'
         from install.rb:205


Not a problem. I just copied lib/diff to the correct spot, but thought 
I should let you know anyway. In case it helps here's uname's output 
and rthe ruby version I'm runnung

$ uname -a
Darwin lemure.local 7.4.0 Darwin Kernel Version 7.4.0: Wed May 12 
16:58:24 PDT 2004; root:xnu/xnu-517.7.7.obj~7/RELEASE_PPC  Power 
Macintosh powerpc

$ ruby -v
ruby 1.8.1 (2003-12-25) [powerpc-darwin]

oh, almost forget this is version 1.0.2 of Diff::LCS

2) I think I've spotted a bug consider the following,

irb(main):031:0> seqw = %w(abcd efgh ijkl mnopqrstuvwxyz)
=> ["abcd", "efgh", "ijkl", "mnopqrstuvwxyz"]

irb(main):032:0> Diff::LCS.diff(seqw,[])
=> [[#<Diff::LCS::Change:0x55b068 @text="efgh", @position=1, 
@action="-">, #<Diff::LCS::Change:0x55b040 @text="ijkl", @position=2, 
@action="-">, #<Diff::LCS::Change:0x55afb4 @text="mnopqrstuvwxyz", 
@position=3, @action="-">]]

irb(main):033:0> Diff::LCS.diff([],seqw)
=> [[#<Diff::LCS::Change:0x5587c8 @text="abcd", @position=0, 
@action="+">, #<Diff::LCS::Change:0x55878c @text="efgh", @position=1, 
@action="+">, #<Diff::LCS::Change:0x558750 @text="ijkl", @position=2, 
@action="+">, #<Diff::LCS::Change:0x558714 @text="mnopqrstuvwxyz", 
@position=3, @action="+">]]
irb(main):034:0>


note the lack of "abcd" as a change in line 2. I would have expected 
the only difference to be "-" to be changed to "+" between the two 
calls. What happened to position 0 in the first call?

J.

On 29/07/2004, at 1:51 AM, Austin Ziegler wrote:

> On Wed, 28 Jul 2004 15:14:02 +0900, jm <jm@transact.com.au> wrote:
>  > A notice that there is a few diff modules of raa. Two questions,
>  >
> > 1) Are any of these the "accepted standard"?
>  > 2) Can any of these take the original array/string/obj/whatever and 
> the
>  > diff it generated and produce the second array that was used to
>  > generate the diff, ie undo the generated diff?
>
> 1) No. Algorithm::Diff by Lars is good, but it is GPL-only. Make sure
>  your licence is compatible. It can do some patching, and I did some
>  work to do some unpatching on it, but it's not in the released
> version.
>  2) Diff::LCS 1.1 (coming soon) will support full context patching and
>  unpatching, but you will have to use a particular sort of call to make
> it happen.
>
> -austin
>  --
> Austin Ziegler * halostatue@gmail.com
> �������������� * Alternate: austin@halostatue.ca