[Python-Dev] Can Python implementations reject semantically invalid expressions?

[Mark Dickinson]

On Fri, Jul 2, 2010 at 3:44 PM, Craig Citro <craigcitro at gmail.com> wrote:
>> Whoa.  That's very peculiar looking bytecode.  Is dis.dis behaving as
>> it should here?
>> BTW, I think you want 'raise TypeError', not 'raise TypeError()'.
>>
>
> Yep, that's embarrassing. I was being lazy: I was expecting different
> bytecodes, and I got it ... so I apparently didn't bother to actually
> read the bytecodes? It's interesting -- if I'd just had TypeError
> instead of TypeError(), I would have found this out, because "raise
> TypeError" is not the bytes representation of a valid sequence of
> bytecodes. ;)

Ah;  interesting.  Well clearly that's exactly what I meant when I
said 'raise TypeError' was better than 'raise TypeError()'. ;-)

(Actually, I confess to being similarly embarrassed:  I have no idea
*what* I was thinking there, since 'raise TypeError()' is just as
valid, if a little less idiomatic.)

> That said, I totally concede Martin's point -- this is an
> implementation-specific thing. It happens that all the major Python
> implementations compile to some VM, and I'd bet that these two compile
> to different bytecodes on any of them, but that doesn't preclude
> another implementation from making a different choice there.

Agreed.

Mark