Python vs Java garbage collection?

[Paul Moore]

pinard at iro.umontreal.ca (François Pinard) writes:

>> [...] The proper code:
>
>>   fp = open('myfile','r')
>>   data = fp.read()
>>   fp.close()
>
>> is not as pretty.
>
> This code is surely proper in Jython, working around the fact that Jython
> relies on Java's garbage collector.

Technically, "correct" code should do

    fp = open('myfile','r')
    try:
        data = fp.read()
    finally:
        fp.close()

as the read() call could raise an exception. And you should catch
exceptions in the open() call. And there are probably other things
that could go wrong.

This is a "practicality beats purity" issue.

The bigger point here is that the C++ "resource acquisition is
initialisation" idiom (and associated principles such as releasing
resources in destructors) doesn't carry across unchanged to Python.
You *can* use the idea, but it's not the end of the story for
exception safety in Python. (For example, Python has "finally", where
C++ doesn't.)

Paul.
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