Marco Sulla wrote: > I can be wrong, but for what I know, del variable_name does not > optimize the code, in the sense of performance.
Correct, by itself `del variable_name` does not optimize the code - however, there exist functions implemented in C (which I gave examples of) with special cases for when `sys.getrefcount(x) == 1`, which means they are free to repurpose an existing object. > allowing the gc to free the memory if that variable was the last reference to > the object. The gc may not be relevant here - in CPython, objects are cleaned up immediately as part of reference counting. The GC only kicks in for circular object graphs. > In a for and a list comprehension, I suppose it's unneeded, since the > variable points automatically to another memory location, so the > reference is removed automatically. The nth reference is not removed until the n+1th reference has been created. This is unavoidable in a for loop without breaking existing code, but I think could (and should?) be changed in a list comprehension > Furthermore, if you want to delete a temporary variable, you could do: > > bc = b * c > a = bc + d > del bc This doesn't hit the optimization I was talking about, because `ndarray.__add__(bc, d)` contains `if sys.getrefcount(self) == 1`, but here the local variable results in a second refcount. _______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/GPQPNUJLRKD32734WQMX5ZIHEZVTOLH2/ Code of Conduct: http://python.org/psf/codeofconduct/
