1

I want to use ag to print the classes and their methods in a python file. I thought that this would be easy using:

ag --context=0 --nocolor -os '^\s*(def|class)\s+[_A-Za-z]*' prog.py

but for reasons I don't understand this is also matching blank lines. For example, if you make prog.py the following

class MyFavouriteClass def __init__ def __contains__ blah class MyNextFavouriteClass def _repr_ def __iter__

then it returns the full file, including the blank lines, except for the line containing blah. Of course, I can always pipe the output into something else to remove the blank lines but I'd rather get it right the first time.

I suspect that the problem has nothing to do with the regular expression and, instead, that it's a feature of ag's --context, --after and --before flags but I can't find a combination of these that does what I want.

Any ideas?

Improve this question
2
  • --context=1 give you one line before and after matches. Commented Aug 10, 2016 at 6:50
  • @cuonglm I first tried --context=0 and it still gives me the blank lines. The --context=1 slipped in after a few edits. You're right in that I should have kept --context=0 in the question -- now fixed. Unfortunately, this doesn't solve my problem. Commented Aug 10, 2016 at 6:51

1 Answer 1

Reset to default
5

It's not the --context, but the \s* at the start of your regex pattern. It seems ag doesn't search line-by-line like normal grep, but looks at the whole file in one go (or at least several lines at a time). A bit like this Perl one-liner would:

perl -0777 -ne 'print "$&\n" while /^\s*(def|class)\s+[_A-Za-z]*/msg' ../prog.py

So, since \s matches any whitespace, including newlines, it matches the previous empty line, the newline, spaces in front of the next, and then the def keyword. If you add an empty line before the blah line, it's not printed, since blah doesn't fit the pattern.

To get rid the unwanted match, use /^ *... or /^[ \t]*... instead of /^\s*.... (space+asterisk in the first one)

Improve this answer
0

You must log in to answer this question.

Start asking to get answers

Find the answer to your question by asking.

Ask question

Explore related questions

See similar questions with these tags.