newbie question - remove a module from ram

[Terry Reedy]

"john fabiani" <jfabiani at yolo.com> wrote in message
news:4AAnc.6791$dH5.4946 at newssvr27.news.prodigy.com...
> Hi,
>
> I believe I have good understanding of import but it occurred to me that
> I might want to remove an imported module.  I.e I load a module into ram
> and I no longer need the module.  Modules just stays in ram?  In the
> windows world I would "thisform.release()"  and the garbage collector
> would release the ram.  So did I miss something or is there no release
> method.  How about a method within a class like destroy()?
>
> I just got to believe it's there????  But where?

The delete statement, in general, directs the interpreter to delete the
association between a name or any other slot and the previously associated
object.  Ditto for function locals at function return.  It does not tell
the interpreter what to do with a object when its last association
disappears.  If, for a particular implementation, it makes sense to talk of
the object being in 'deletable memory' (and, for humans, it hardly does,
nor would it for read-only machine memory, nor, possibly, for 'builtin'
modules), then the standard *allows* but does not *require* deletion.

CPython currently caches a reference to modules so that code like the
following won't tear down a module as it returns and have to rebuild it at
every call:

def sincos(x):
    import math as m # for the purpose of this example, assume this is only
math import
    return sin(x), cos(x)

Modules are sufficiently small, sufficiently expensive to set up, and
sufficiently often reused, that I has not been thought worthwhile to add a
modwipe function to countervail the cache effect, which itself was added to
countervail the usual CPython delete-object- with-last-reference behavior.

Terry J. Reedy