True

[Andrew Bennetts]

Re: True

On Sun, Oct 19, 2003 at 08:17:15AM -0700, David Eppstein wrote:[color=blue]
> In article <3f929cf0$1_1@t hemost.net>,
> "Paul Watson" <pwatson@redlin ec.com> wrote:
>[color=green]
> > Then, what is the best way to write boolean operations for Python 2.1 so
> > that it will be as 2.3+ ready as possible?[/color]
>
> I've been including the following at the start of some of my code:
>
> if 'True' not in globals():
> globals()['True'] = not None
> globals()['False'] = not True[/color]

Why not simply:

try:
True
except NameError:
True = (1 == 1) # or not None, if you prefer
False = not True

Or were you trying to change the __builtins__ by using globals()?

-Andrew.

[Duncan Booth]

Re: True

David Eppstein <eppstein@ics.u ci.edu> wrote in news:eppstein-
D286CF.08171519 102003@news.ser vice.uci.edu:
[color=blue][color=green]
>> Then, what is the best way to write boolean operations for Python 2.1 so
>> that it will be as 2.3+ ready as possible?[/color]
>
> I've been including the following at the start of some of my code:
>
> if 'True' not in globals():
> globals()['True'] = not None
> globals()['False'] = not True
>
> My hope is that setting up True and False in this convoluted way will
> allow it to continue to work in some future version where assignment to
> builtins is disallowed.[/color]

Since True will never be in globals unless you assign it there, you might
as well just drop the if statement altogether. Also I fail to see what
benefit you gain from the contorted assignment into the globals dictionary.
Why not just write:

True = not None
False = not True

It has the same effect overall.

If you want to avoid hiding the builtin True and False, then use try..catch
to detect them.

--
Duncan Booth duncan@rcp.co.u k
int month(char *p){return(1248 64/((p[0]+p[1]-p[2]&0x1f)+1)%12 )["\5\x8\3"
"\6\7\xb\1\x9\x a\2\0\4"];} // Who said my code was obscure?

[Peter Otten]

Re: True

Andrew Bennetts wrote:
[color=blue]
> On Sun, Oct 19, 2003 at 08:17:15AM -0700, David Eppstein wrote:[color=green]
>> In article <3f929cf0$1_1@t hemost.net>,
>> "Paul Watson" <pwatson@redlin ec.com> wrote:
>>[color=darkred]
>> > Then, what is the best way to write boolean operations for Python 2.1
>> > so that it will be as 2.3+ ready as possible?[/color]
>>
>> I've been including the following at the start of some of my code:
>>
>> if 'True' not in globals():
>> globals()['True'] = not None
>> globals()['False'] = not True[/color]
>
> Why not simply:
>
> try:
> True
> except NameError:
> True = (1 == 1) # or not None, if you prefer
> False = not True
>
> Or were you trying to change the __builtins__ by using globals()?
>
> -Andrew.[/color]

I suppose David tries to avoid a syntax error raised by the assignment

True = somethingElse

in a future version of Python. Therefore he has "hidden" the builtins to be
assigned from the compiler by turning them into strings.

Peter

[David Eppstein]

Re: True

In article <bn0cf2$liu$01$ 1@news.t-online.com>,
Peter Otten <__peter__@web. de> wrote:
[color=blue]
> I suppose David tries to avoid a syntax error raised by the assignment
>
> True = somethingElse
>
> in a future version of Python. Therefore he has "hidden" the builtins to be
> assigned from the compiler by turning them into strings.[/color]

Yes, exactly.

--
David Eppstein http://www.ics.uci.edu/~eppstein/
Univ. of California, Irvine, School of Information & Computer Science