[Python-Dev] Why is Bytecode the way it is?

[Phillip J. Eby]

At 07:14 AM 7/8/04 -0700, Paul Prescod wrote:

>I'm really not even proposing a change to Python as much as trying to 
>understand why it is the way it is. I can see how a stack is helpful for 
>evaluating deeply nested expressions (although temporary variables seems 
>another good valid approach). I just don't see the payoff for shuffling 
>variables from locals onto the stack and back into the locals table.

The payoff is in shorter development time...  of the compiler.  :)

Essentially, most of Python compilation is simply rearranging expressions 
to be postfix notation instead of infix notation.  Thus, it's relatively 
straightforward to write a compiler for, because the bytecode emissions 
match the recursive structure.  Although you need to keep track of the 
maximum stack depth, you don't need to worry about register allocation.