From: "Gregg N" 

Ellen K. wrote:
> Me too.
>
> On Tue, 19 Apr 2005 22:34:44 +0100, Adam Flinton
>  wrote in message :
>
>> I have to admit to still prefering to merge by eye (i.e. "show me the
>> changes/differences but I'll do the copy & paste till my local
copy &
>> the remote fit")

That is not workable in any but the most trivial cases. Support from the
source control system is required to peform typical project-wide branching
and merging involving a few hundred files. This happens for example when
you've branched the project to create released version and then you need to
incorporate various bug fixes back onto the trunk where ongoing development
is still occurring.

The source control tool manages the comparison between the correct versions
of the checked-in files and automatically checks out, meges, and checks
back in automatically. If there are no lexical conflicts (the changes do
not affect the same lines) there is no need for manual intervention. If
there are conflicts, the source control system opens a merge tool that
presents you with nice side-by-side view of the two versions and the merged
result at the bottom, with conflicts highlighted. You have the ability to
pick and choose which of the conflicting lines you want to incorporate, or
you can edit them directly. Why would you prefer to do this without the
help of such a tool?

The only caveat is that lack of lexical conflict does not guarantee lack of
semantic conflict. This you have to verify by testing, but if you are not a
sloppy programmer, it should not happen often. Finally, the source control
system maintains history of all the files, so you always have the ability
to revert to older versions of code, and you can easily see what the merge
process changed.

Gregg

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