A fun python CLI program for all to enjoy!
alister
alister.ware at ntlworld.com
Sat May 7 04:51:50 EDT 2016
On Sat, 07 May 2016 18:24:45 +1200, Gregory Ewing wrote:
> DFS wrote:
>> Maybe it worked because the last time the file was written to was in a
>> for loop, so I got lucky and the files weren't truncated? Don't know.
>
> It "works" because CPython disposes of objects as soon as they are not
> referenced anywhere. Other implementations of Python (e.g. Jython, PyPy)
> might not do that.
to provide an example try the following code in the interactive
interpreter
>>>f=open('somefile','w')
>>print f.write('line 1')
None
>>>print f.close
built-in method close of file object at 0x7fb4c9580660>
>>>print f.write('line 2')
None
>>>print f.close()
None
>>>print f.write('line 3')
ValueError: I/O operation on closed file
somefile will contain
line 1
line 2
--
manager in the cable duct
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