Something keeps nibbling on my list

[Steve Purcell]

michael wrote:
> EXCLUDE=''   #Lines beginning with this should not be printed.
> 
> def get_line() :
>   buf = f.readline()
>   if (buf and buf[0] == EXCLUDE):
>     return 0
>   else:
>     return buf


If 'EXCLUDE' is '', buf[0] will never == EXCLUDE.

Imagine that you want to exclude lines beginning with '#'. I think you
could then write your whole program as follows:

    FILENAME = '/etc/hosts.deny'
    OUTPUT = 'hosts.deny.test'

    orig = open(FILENAME)
    lines = orig.readlines()
    orig.close()

    def skip(line):
       return line[:1] == '#'

    filtered = open(OUTPUT,'w')
    for linenum in range(len(lines)):
       line = lines[linenum]
       if skip(line):
	   continue  
       if line in lines[:linenum]:   # duplicate
	   continue                             
       filtered.write(line)

    filtered.close()



-Steve

-- 
Steve Purcell, Pythangelist
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