On 5/04/21 11:47 am, dn wrote:
I think I've read that the compiler is smart-enough to realise that the
RHS 'literal-tuples'?'tuple-literals' are being used as a 'mechanism',
and thus the inits are in-lined.
It does indeed seem to do this in some cases:
>>> def g(i, j, k):
... a, b, c = i, j, k
...
>>> dis(g)
2 0 LOAD_FAST 0 (i)
2 LOAD_FAST 1 (j)
4 LOAD_FAST 2 (k)
6 ROT_THREE
8 ROT_TWO
10 STORE_FAST 3 (a)
12 STORE_FAST 4 (b)
14 STORE_FAST 5 (c)
16 LOAD_CONST 0 (None)
18 RETURN_VALUE
If the RHS is a literal, it's a bit different:
>>> def f():
... a, b, c = 1, 2, 3
...
>>> dis(f)
2 0 LOAD_CONST 1 ((1, 2, 3))
2 UNPACK_SEQUENCE 3
4 STORE_FAST 0 (a)
6 STORE_FAST 1 (b)
8 STORE_FAST 2 (c)
10 LOAD_CONST 0 (None)
12 RETURN_VALUE
Here the tuple creation is being done at compile time,
so there's still an unpacking operation. It might not be
much different speed-wise from loading the values separately,
though.
--
Greg
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