Bruce Leban wrote:
On Wed, Jun 1, 2011 at 9:56 AM, Ethan Furman wrote:
Several times in that thread it was stated that
--> a += 1
is a shortcut for
--> a.__iadd__(1)
It seems to me that this is an implementation detail, and that the actual "longcut" is
--> a = a + 1
...
~Ethan~
a += 1 is not a shortcut for a.__iadd__(1). It's a shortcut for a = a.__iadd(1). Otherwise this wouldn't work:
Right -- typo on my part, sorry.
Note the difference between these two is one opcode:
def f(x,y): x += y dis.dis(f) 2 0 LOAD_FAST 0 (x) 3 LOAD_FAST 1 (y) 6 *INPLACE_ADD* 7 STORE_FAST 0 (x) 10 LOAD_CONST 0 (None) 13 RETURN_VALUE def g(x,y): x = x + y
dis.dis(g) 2 0 LOAD_FAST 0 (x) 3 LOAD_FAST 1 (y) 6 *BINARY_ADD* 7 STORE_FAST 0 (x) 10 LOAD_CONST 0 (None) 13 RETURN_VALUE
Note also that INPLACE_ADD will call the the BINARY_ADD method if no __iadd__ method exists. ~Ethan~