Re: The C Stack in interpreters - why?

By "A lot of languages use the C stack" I mean that many interpreters
coded in C call their bytecode evaluation loop recursively whenever
they enter a new function in the interpreted language. For example,
here is a statement from the Python FAQ:


"Answer 1: Unfortunately, the interpreter pushes at least one C stack
frame for each Python stack frame. Also, extensions can call back into
Python at almost random moments. Therefore, a complete threads
implementation requires thread support for C.


Answer 2: Fortunately, there is Stackless Python, which has a
completely redesigned interpreter loop that avoids the C stack. It's
still experimental but looks very promising."
[That's the hardware stack on computers that have one. The point
they're making is that if you use the regular call stack and want to
do threads in your interpreter, you need a thread package that will
thread at the C level. If you maintain your own stacks for the
interpreter, you can do your own thread package. If you don't want to
do anything that C doesn't do, it's a whole lot easier to use the C
stack than to do explicit allocation and deallocation. -John]

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