Re: good patch vs. sed fixes

On Mon, Nov 25, 2024 at 02:10:06PM +0100, Rainer Fiebig wrote:
> Am 25.11.24 um 04:46 schrieb Ken Moffat ([email protected] via
> blfs-dev Mailing List):

> As you know, one can be very specific with addresses in sed.  And one
> can test in advance whether other lines would be affected.  With the
> Seamonkey-2.53.19 sources:
> 
> > sed --silent '/ZWJ/p' intl/lwbrk/LineBreaker.cpp
>     /* ZWJ = 42,                          [ZWJ]*/ CLASS_CHARACTER
> 
> So if using /ZWJ/ for the address, no other lines would be affected.
> Instead of sed one could also use grep or an editor.
> 
> Now testing what the sed will do, using that from ch. Seamonkey:
> > (for i in {43..47}; do
>    sed '/ZWJ/s/$/,CLASS_CHARACTER/' -i.orig intl/lwbrk/LineBreaker.cpp
> || exit $?
> done)
> 
> Checking the result, here with grep.  By using -i.orig one still has a
> backup of the file:
> > grep 'ZWJ' intl/lwbrk/LineBreaker.cpp
>     /* ZWJ = 42,                          [ZWJ]*/
> CLASS_CHARACTER,CLASS_CHARACTER,CLASS_CHARACTER,CLASS_CHARACTER,CLASS_CHARACTER,CLASS_CHARACTER
> 
> 
> This procedure is pretty simple and quickly provides the desired
> information.
> 

Noted.

> > 
> > In many cases, a sed will change other lines which do not matter.
> As said, one can be very specific with addresses in sed.  If necessary,
> one could take the whole line as the regexp for the address.
> 

Try doing that in C++ code which needs to be be updated for a newer
C++ version but has several sets of parentheses and several sets of
squate brackets.  I assume it can probably be done, but with a
horrendously long regex.

> > On occasion when I was editing I attempted to limit a sed to only
> > the desired lines (without specifying line numbers, of course) but
> > often that was impractical.
> Why _not_ use line numbers in such cases?  If there really are several
> _identical_ lines and you don't want all of them to be changed then use
> line numbers.
> 

Line numbers worh in the current version.  As soon as something
changes in the file, line nubers still apply (unless now after EOF)
but will do nothing useful

> > 
> > For those who are happy to only follow the book, and to assume that
> > editors do not make mistakes or apply seds which in fact no longer do
> > anything, none of that is an issue.
> Which would be the vast majority of users.  And for them it's also
> easier to just copy and paste a sed instead of having to download and
> apply several hundreds of additional patches.  Not to mention the
> educational value of learning how to use sed.
> 
> >  But for those who care about
> > the development of LFS or BLFS it is something to bear in mind as
> > versions of packages change.
> Ken, I really don't have a clue what you want to tell me here.  But my
> POV is that if a user deliberately or by lack of diligence deviates from
> the books and runs into problems, it's first and foremost up to him to
> solve them, if necessary with help from the support-lists.  One cannot
> make a case for substituting sed-statements with patches from that.
> 
> Rainer

This list was originally for the development of the book. Uwe's
posts were related to changes for a newer version.  For development,
being prepared to deviate from the current book is necessary.

I agree that learning sed can be a useful skill.

ĸen
-- 
The Soemrset Nog - a cross between a Suffolk Punch and a Dachshund.
It gets very foggy on the moors.
 -- Kenneth Williams as Rambling Syd Rumpo.

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