a possibly foolish question about slices

[holger krekel]

Garth T Kidd wrote:
> > x[p:][:n]
> 
> Does the parser take the appropriate short-cut, here, or do we end up
> with a temporary list?

the parser looks at syntax rather than semantics. You probably mean the 
compiler or bytecode-generator. This is the roughly the bytecode:

>>> f=lambda x: x[3:][:7]
>>> import dis
>>> dis.dis(f)
          0 SET_LINENO               1
          3 LOAD_FAST                0 (x)
          6 LOAD_CONST               1 (3)
          9 SLICE+1
         10 LOAD_CONST               2 (7)
         13 SLICE+2
         14 RETURN_VALUE

The SLICE+1 outcome/sideeffects cannot be predicted by the compiler,
so he simply does what you say.

regards,

    holger