I'm looking for a the most simple and generic way to modify a file, with the
possibility of making backups. In fact, I would like to emulate Perl's -i
option.
here is a bit of code, to explain it further :
< code >
from os import rename
class Modif_File:
def __init__(self, filename, ext='.bak'):
old_name = filename + ext
new_name = filename
rename(new_name,old_name)
self.old = open(old_name,'r')
self.new = open(new_name,'w')
# methods for getting data are linked to the old file :
for attr in ('encoding', 'newlines', 'next', 'read',
'readinto', 'readline', 'readlines', 'seek',
'tell', 'xreadlines'):
setattr(self,attr,getattr(self.old,attr))
# methods for putting data are linked to the new one :
for attr in ('closed','flush','write', 'writelines'):
setattr(self,attr,getattr(self.new,attr))
def close(self):
self.new.close()
self.old.close()
</ code >
for example, an equivalent of
perl -i.bak -pe 's/\t+$//' *txt
could be :
< code >
from glob import glob
from re import compile, MULTILINE
regex = compile(r'\t+$',MULTILINE)
for f in [Modif_File(name) for name in glob('*.txt')]:
f.write(regex.sub('',f.read()))
f.close()
</ code >
Of course, this example is very basic and my class Modif_File does not take
into account :
- the right of the file
- the mode of the file (binairy/text)
- ...etc
What is the best way to do it ?
--
Elby
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