On 06/09/2023 03:47, Daniel Walker wrote:
Perhaps this is a solution in search of a problem but I recently
encountered this situation in one of my projects.
I have an object, foo, which, due to the references it contains, I'd
rather not keep around longer than necessary.
I use foo to instantiate another object:
bar = Bar(foo)
bar is free to manipulate foo however it wants and even del it if
necessary. However, since the foo name is still around, those
resources won't get cleaned up even if bar is done with them. The
simple solution is
It's a neat idea but there are other ways that may be better.
I assume foo is a "specification", that is, an object you configure
through a number of optional calls or attribute assignments, then pass
to Bar() as a design alternative to Bar() having a complicated set of
arguments. A pattern often used is the fluent API:
bar = Bar(Foo().a().b(42).c('penguin'))
Now only Bar has a reference to the Foo you made.
But foo is not necessarily destroyed immediately the last reference to
it is dropped, even with del or when nameless in the fluent API. If you
wanted to be certain, you could make Foo a context manager to use like this:
with Foo() as foo:
foo.a()
foo.b(42)
foo.c('penguin')
bar = Bar(foo)
bar.do_stuff()
(Think I got that right. Not tried it.) Now Foo.__exit__ can be made to
properly tear down the resources in a foo.
--
Jeff Allen
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