Why does IDLE use a subprocess?

[Greg Ewing]

On 29/05/23 8:10 am, James Schaffler wrote:
> However, some minimal testing of InteractiveInterpreter leads me to believe that the Interpreter object has its own view of local/global variables and therefore shouldn't be able to affect the calling interpreter

Globals you create by executing code in the REPL have their own
namespace. But everything else is shared -- builtins, imported
Python modules, imported C extension modules, etc. etc.

There's a long-running project to make it possible to have
multiple fully-isolated Python interpreters in one process, but
the way CPython is structured makes that very difficult to achieve,
and as far as I know it's not there yet.

In the case of IDLE, there's really no reason not to use a
subprocess[1]. It's easy and guarantees 100% isolation.

[1] Well, mostly. There used to be a small hitch on Windows with
the default firewall settings not letting you connect to a local
socket (nice one, Microsoft). I don't know whether that's still
an issue.

-- 
Greg