Towards faster Python implementations - theory

[Terry Reedy]

<olsongt at verizon.net> wrote in message 
news:1178821414.998672.247260 at w5g2000hsg.googlegroups.com...
| The idea is to create a special dictionary for python internals that
| contains a pointer-to-a-pointer for the value side of the dictionary,
| instead of just the standard PyObject*.  Then when you start to eval a
| code block, you could do a one-time lookup of the pointer-to-the-
| pointer for each method, attribute, etc; and store them in pre-
| allocated slots.  The calls in the block to various GET_ and SET_
| functions can then just deal with pointer derefencing instead of a
| dictionary lookup, and the dictionary can still get changed while this
| is going on without things blowing up.
|
| I think you'd get a big speed up by changing all those dictionary
| function calls to inlined pointer deref code.
|
| Anyone else buy this approach? Or see any fatal flaws?

Within CPython functions, local variables are usually implemented as 
numbered slots in a C array (of PyObject pointers).  There is why a) the 
compiler makes a first pass thru a function body (to determine what is 
local and what is not) and b) LOAD_FAST is faster than LOAD_GLOBAL.

Terry Jan Reedy