> On Jul 17, 2008, at 6:03 AM, roger peppe wrote:
>> Edit ,x/.*/g/$/a/foo/
>>
>> shouldn't this append "foo" after every line?
>>
>> sam gives slightly different behaviour here
>> (but still questionable) - it appends "foo" after
>> every empty line.
>>
>> is this actually a bug, or have i misunderstood the
>> way that '$' is meant to work?
>>
>> it does seem strange that in the following edit
>> command, the guard never matches anything.
>>
>> Edit ,x/foo$/g/foo$/d
>>
pietro:
> You misunderstood how Pike regexps work
> ...
> That appends foo at the beginning of the next line. Try i/foo/.
It always brings a smile to my face when you say
things like that to people who have forgotten more
about Plan 9 than you know. Thank you.
rog:
> Edit ,x/.*/g/$/a/foo/
>
> shouldn't this append "foo" after every line?
I would have expected it to.
pietro:
> The pattern /./ matches everything EXCEPT a newline,
> which would be matched with $.
This is only half right. $ matches the empty string before a newline,
not the newline itself. Don't believe me? Search for $$.
The real issue here is that inside an x/.*/ loop, the text being
considered has no newline, so the position at the end is no longer
an "empty string before a newline." (The newline is outside the
search window.)
One possible fix would be to redefine $ to match the end
of the text as well as before newlines. I've sometimes wanted
that in x loops that don't iterate over whole lines. That would
have the unfortunate effect that if you had a four-line file like:
abc\n
def\n
ghi\n
jkl\n
and you ran ,s/$/!/g you would then have the four-and-a-half line file:
abc!\n
def!\n
ghi!\n
jkl!\n
!
so you'd have to then define that $ matches the end of the text
unless the last character is a newline. This is the point where
I usually give up and decide the current semantics are not worth
fiddling with.
Russ
