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Finding strings with exceptions

David Brady daves_spam_dodging_account at yahoo.com
Mon Dec 3 12:47:43 EST 2001 
Hello,

I'm trying to grep through a project, and I've come
across this problem many times in the past. 
Previously, doing this problem in perl, I've just
given up because my perl regex skill is "merely
competent" and not wizardly.

Today I ran into the same problem, and since Python
has amazed me countless times already, I figured that
it might be possible.

What I want to do is find all instances of an
expression EXCEPT those that also match another
expression.  The case in point for today was this: I
was called away from my machine in the middle of
refactoring some code.  I was renaming a class to
conform to our project's coding standards, and the new
name requires a prefix.

The old class name (changed to protect the innocent)
is BarThingy.  The new name is fooBarThingy.  Because
the new class name contains the old one, simple
find-and-replace goes wonky.  In the reverse case, I
could put something in the regex that says, "also find
an optional prefix 'foo'."  But what I really want to
do is find the class everywhere EXCEPT where that
'foo' prefix exists.  Anyone know a good way to do
this?

Note that one cannot simply grep all the lines that
contain BarThingy and then remove lines that contain
fooBarThingy, because a single line might contain
both.  Hmm, in writing this, I wonder if I could look
for foo as an optional group, and call a function that
causes the regex to fail if the group is present...
hmmmm....

Thanks,

-dB

=====
David Brady
daves_spam_dodging_account at yahoo.com
I'm feeling very surreal today... or *AM* I?

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