text file edit object

[Skip Montanaro]

    Facundo> What about something like this:

    Facundo> try:
    Facundo>    infile = file("foo.txt", "r")
    Facundo>    lines = infile.readlines()[:-10]
    Facundo>    infile.close()
    Facundo>    outfile = file("foo.txt.new", "w")
    Facundo>    outfile.writelines(lines)
    Facundo>    outfile.close()
    Facundo> except:
    Facundo>    print >> sys.stderr, "edit failed"
    Facundo>    raise
    Facundo> else:
    Facundo>    os.rename("foo.txt2", "foo.txt")

Yes, that's what I thought of first, however the errors (and how you recover
from them) are different between the reading and writing phases.

    Facundo> One question: is this method (file, readlines) efficient on big
    Facundo> files?

Should be, though you have the obvious overhead of gulping the entire file.
For very large files it would probably be more efficient to read the file in
smaller chunks and only avoid writing the last ten lines.  However, the code
gets that much more baroque. ;-)

Skip