On 2018-10-11 13:57:57 +0200, Thomas Jollans wrote: > There's no easy way to write to the middle of a file (though I think it > can be done by mmap'ing a file)
#!/usr/bin/python3
import os
with open("foo.bin", "wb") as f:
f.write(b'abcdefghijklmnopqrstuvwxyz')
with open("foo.bin", "rb") as f:
print("-----")
for i, c in enumerate(f.read()):
print("%2d %2x" % (i, c))
with open("foo.bin", "r+b") as f:
f.seek(10, os.SEEK_SET)
f.write(b'000')
f.seek(20, os.SEEK_SET)
f.write(b'11')
f.seek(30, os.SEEK_SET)
f.write(b'2')
with open("foo.bin", "rb") as f:
print("-----")
for i, c in enumerate(f.read()):
print("%2d %2x" % (i, c))
Mmap doesn't allow you to do anything you can't do with normal file I/O.
It's just sometimes more convenient and/or performant.
> -- and even if you manage to do that,
> you'd have to write back anything after the changed line if the length
> of that line changed by as little as a byte.
This is correct.
hp
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