On Fri, Sep 22, 2017 at 3:23 AM, Steve D'Aprano
<steve+pyt...@pearwood.info> wrote:
> That is definitely version-dependent, because I've just tried it and got
> different byte-code in Python 2.7.
>
> py> import dis
> py> def test1():
> ... assert foo, "bar baz"
> ...
> py> def test2():
> ... if not foo: raise AssertionError("bar baz")
> ...
> py>
> py> dis.dis(test1)
> 2 0 LOAD_GLOBAL 0 (foo)
> 3 POP_JUMP_IF_TRUE 15
> 6 LOAD_GLOBAL 1 (AssertionError)
> 9 LOAD_CONST 1 ('bar baz')
> 12 RAISE_VARARGS 2
> >> 15 LOAD_CONST 0 (None)
> 18 RETURN_VALUE
> py> dis.dis(test2)
> 2 0 LOAD_GLOBAL 0 (foo)
> 3 POP_JUMP_IF_TRUE 21
> 6 LOAD_GLOBAL 1 (AssertionError)
> 9 LOAD_CONST 1 ('bar baz')
> 12 CALL_FUNCTION 1
> 15 RAISE_VARARGS 1
> 18 JUMP_FORWARD 0 (to 21)
> >> 21 LOAD_CONST 0 (None)
> 24 RETURN_VALUE
Impressive. That means that, in 2.7, it's actually equivalent to:
>>> def test3():
... if not foo: raise AssertionError, "bar baz"
...
>>> dis.dis(test3)
2 0 LOAD_GLOBAL 0 (foo)
3 POP_JUMP_IF_TRUE 18
6 LOAD_GLOBAL 1 (AssertionError)
9 LOAD_CONST 1 ('bar baz')
12 RAISE_VARARGS 2
15 JUMP_FORWARD 0 (to 18)
>> 18 LOAD_CONST 0 (None)
21 RETURN_VALUE
Although in the 2.7 that I have, the assert statement does actually
*call* AssertionError (ie it constructs an instance and raises it).
What version are you running? Here's mine:
$ python2
Python 2.7.13 (default, Jan 19 2017, 14:48:08)
[GCC 6.3.0 20170118] on linux2
Type "help", "copyright", "credits" or "license" for more information.
ChrisA
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