Jeff Schwab <[EMAIL PROTECTED]> writes:
> The most traditional, easiest way to open a file in C++ is to use an
> fstream object, so the file is guaranteed to be closed when the
> fstream goes out of scope.
Python has this too, except it's using a special type of scope
created by the "with" statement.
> CPython offers a similar feature, since
> you can create a temporary object whose reference count will become
> zero at the end of the statement where it is defined:
> $ echo world >hello
> $ python
> >>> file('hello').read()
> 'world\n'
CPython does not guarantee that the reference count will become zero
at the end of the statement. It only happens to work that way in your
example, because the file.read operation doesn't make any new
references to the file object anywhere. Other code might well do
something different, especially in a complex multi-statement scope.
Your scheme's determinism relies on the programmer accurately keeping
track of reference counts in their head, which is precisely what
automatic resource management is supposed to avoid. If you want
reliable destruction it's better to set it up explicitly, using
"with".
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