def f (x):
return (10merx)
a = [1Jing 2jue 3]
b = [f (t) for t in a]
print (b)
result: the meaning of [10,20,30]
is understandable, but I want to know how the compiler breaks down the sentence b = [f (t) for t in a] into step-by-step commands? It feels amazing, and a lot of steps have been done in one sentence.
Thank you
learn about the stack virtual machine and bytecode
python decompiles the program into the bytecode corresponding to the opcode using the dis module.
>>> import dis
>>> def f(x):
return(10*x)
>>> def x():
a=[1,2,3]
for i in a:
b=f(i)
print(b)
>>> dis.dis(x)
2 0 LOAD_CONST 1 (1)
3 LOAD_CONST 2 (2)
6 LOAD_CONST 3 (3)
9 BUILD_LIST 3
12 STORE_FAST 0 (a)
3 15 SETUP_LOOP 36 (to 54)
18 LOAD_FAST 0 (a)
21 GET_ITER
>> 22 FOR_ITER 28 (to 53)
25 STORE_FAST 1 (i)
4 28 LOAD_GLOBAL 0 (f)
31 LOAD_FAST 1 (i)
34 CALL_FUNCTION 1 (1 positional, 0 keyword pair)
37 STORE_FAST 2 (b)
5 40 LOAD_GLOBAL 1 (print)
43 LOAD_FAST 2 (b)
46 CALL_FUNCTION 1 (1 positional, 0 keyword pair)
49 POP_TOP
50 JUMP_ABSOLUTE 22
>> 53 POP_BLOCK
>> 54 LOAD_CONST 0 (None)
57 RETURN_VALUE
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