Verifiably better, validated Enum for Python

[bartc]

On 26/05/2017 12:46, Steve D'Aprano wrote:
> On Thu, 25 May 2017 11:26 am, Chris Angelico wrote:

>> And why should they try to stop you? The whole point of undefined
>> behaviour is that you shouldn't be doing this, so if you do, the
>> interpreter's allowed to do anything.
>
> Does the C specification actually refer to this as undefined? I'm not a C
> expert, but it seems to me that it is defined as an error. I tried
> compiling that code:
>
>
> [steve at ando c]$ cat stringassign.c
> #include <stdio.h>
> #include <stdlib.h>
>
> int main(int argc, char *argv[])
> {
>   "abcdef"[3] = 'z';
>   puts("abcdef");
>   return 0;
> }
> [steve at ando c]$ gcc stringassign.c
> stringassign.c: In function ‘main’:
> stringassign.c:6: error: assignment of read-only location
>
>
> but I couldn't get it to succeed.

Compilers will vary.

In gcc for Windows, I get the same message but as a warning.

With DMC, nothing. With Pelles C, nothing. With lccwin, nothing. With 
Tiny C, nothing. With MSVC 2008, nothing.

(Only my own compiler will give a hard error, but that's because I 
specify detect that. In general, the language can't stop you writing to 
such a string, one way or another.)

Note that compiled as C++, I think this has to fail (because string 
literals have slightly different types compared with C).

-- 
bartc