Is Python type safe?

[Skip Montanaro]

Re: Is Python type safe?

[color=blue][color=green]
>> Sorry to follow up to my own post, but unions also create type
>> unsafety.[/color][/color]

Roy> Of course you can. Given C's roots as a high level assembly
Roy> language, why would you expect anything else?

Nope. But the user asked if C++ was type safe. The presence of unions
indicates that it's not, at least in some situations.

Roy> I was once asked on an interview how I would tell, inside of a C
Roy> program, if I was on a big endian or a small endian machine. I
Roy> said I'd create a union of a long and a char[4], set the long equal
Roy> to 1, and see which char it showed up in. The interviewer looked
Roy> shocked, thought about it for a while, and finally said something
Roy> like, "yeah, I guess that would work".

Sure. There are plenty of reasons to use unions. They can be a
double-edged sword though.

Skip

[Carl Banks]

Re: Is Python type safe?

Roy Smith wrote:[color=blue]
> I was once asked on an interview how I would tell, inside of a C
> program, if I was on a big endian or a small endian machine. I said I'd
> create a union of a long and a char[4], set the long equal to 1, and see
> which char it showed up in. The interviewer looked shocked, thought
> about it for a while, and finally said something like, "yeah, I guess
> that would work".
>
> To this day, I have no idea what other plan he had in mind.[/color]


Here's my guess:

long i = 0;
*(short*)&i = 1;

if (i == 1) { printf("It's whatever one Intel uses.\n"); }
else { printf("It's the other one.\n"); }


--
CARL BANKS http://www.aerojockey.com/software
"If you believe in yourself, drink your school, stay on drugs, and
don't do milk, you can get work."
-- Parody of Mr. T from a Robert Smigel Cartoon

[Erik Max Francis]

Re: Is Python type safe?

Carl Banks wrote:
[color=blue]
> Here's my guess:
>
> long i = 0;
> *(short*)&i = 1;
>
> if (i == 1) { printf("It's whatever one Intel uses.\n"); }
> else { printf("It's the other one.\n"); }[/color]

You meant char, not short.

And none of the solutions so far acknowledge the fact that none of these
types have absolute sizes as defined in the Standard. If I were
conducting the interview, I'd take points off if that weren't at least
acknowledged.

--
__ Erik Max Francis && max@alcyone.com && http://www.alcyone.com/max/
/ \ San Jose, CA, USA && 37 20 N 121 53 W && &tSftDotIotE
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-- Anggun

[Joe Mason]

Re: Is Python type safe?

In article <roy-0B9FC3.17134816 032004@reader1. panix.com>, Roy Smith wrote:[color=blue]
> I was once asked on an interview how I would tell, inside of a C
> program, if I was on a big endian or a small endian machine. I said I'd
> create a union of a long and a char[4], set the long equal to 1, and see
> which char it showed up in. The interviewer looked shocked, thought
> about it for a while, and finally said something like, "yeah, I guess
> that would work".
>
> To this day, I have no idea what other plan he had in mind.[/color]

unsigned short x = 1;
if (x == ntohs(x)) printf("Network byte order!\n");
else printf("Somethi ng else!\n");

Joe