[Tutor] Redux: optparse

[Matt Herzog]

> Do you want to use optparse, or get the command line arguments yourself?
> It seems the pattern string will be the first arg, will it?

Again I am confused. I assumed that optparse was the best way to pass in arguments (such as filenames) from the command line. Like so:

	./script.py -x regex *.html

> > rx = re.compile('-x')
> 
> Then, if the note above is right, you have:
> 
> pat_string = sys.argv[1]
> rx = re.compile(pat_string)   # pattern object
> 
> Is that what you wish to do?

Probablement. :) The below code does what I want:

-------------------------------------------------------------------------------
#!/usr/bin/python
import fileinput, sys, string
# Take the first argument out of sys.argv and assign it to searchterm.
searchterm, sys.argv[1:] = sys.argv[1], sys.argv[2:]
for line in fileinput.input():
   num_matches = line.count(searchterm)
   if num_matches: # A nonzero count means there was a match.
       print "found '%s' %d times in %s on line %d." % (searchterm, num_matches, fileinput.filename(), fileinput.filelineno())
-------------------------------------------------------------------------------

I wanted to use optparse instead of sys.argv. Perhaps I should study fileinput instead. I don't understand that either.
 
> > for line in fileinput.input():
> >     num_matches = string.count(line, rx)
 
> Above you are counting the number of *regex pattern* may be inside a
> string. Not the number of (sub)strings matching the pattern, which is
> probably what you intend.[ Also, you are using a deprecated function
> "count" of the string module. Use line.count(substring) instead. Anyway,
> this is probably not what you want.]
> To count the number of pattern matches, you must use the
> "matching" (lol) regex method, namely findall:
> 
> result_list = rx.findall(line)
> 
> > if num_matches:
> >     print "found '%s' %d times in %s on line %d." % (rx, num_matches,
> >         fileinput.filename(), fileinput.filelineno())
> 
> Do you want to print only the last match? If not, you need to record
> matches found by the search loop into a list.
> 
> > #if __name__ == '__main__':
> >     #main()
> 
> 
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