OpenEuphoria

Re: ESL Master Include File

• Posted by "Juergen Luethje" <j.lue at gmx.de> Jul 26, 2005
• 561 views

Derek Parnell wrote:

> Pete Lomax wrote:
>
> [snip]
>> Despite the highly unlikely chance
>> of such things, some libraries actually do define TRUE=(1=1) and
>> FALSE=(1=0).
>
> That would be me 
>
>> There is nothing wrong with using tri-logic with say isTLtrue=1,
>> isTLunknown=0, and isTLfalse=-1, (though isTLfalse=0, and
>> isTLunknown=-1 would probably be just as effective) but
>> defining FALSE as -1 is just brain-dead stupidity.
>
> Why? The only requirement is that TRUE and FALSE have different values
> from each other. One could have ...
>
> constant  TRUE  = 't',
>           FALSE = 'f'
>
> And all code that relied on using TRUE and FALSE would still work.
> One's code should never be doing arithetic on boolean values and never
> doing relative comparisions either (less than, greater than). Instead
> one's code should only be doing assignments and equality tests.

What about boolean operations such as 'not'?

constant
   FALSE = 0,
   TRUE = 1

? TRUE = not FALSE  -- prints 1 (which equals TRUE here) -> correct

constant
   FALSE = -1,
   TRUE = 1

? TRUE = not FALSE  -- prints 0 (which is not a boolean value here!)

constant
   FALSE = 'f',
   TRUE = 't'

? TRUE = not FALSE  -- prints 0 (which is not a boolean value here!)

> BTW, and I'm sure you already know this, but there are plenty of
> languages that implement TRUE as -1 instead of 1.

Then hopefully the boolean operators in these languages work
consistently, so that always
   not FALSE = TRUE
   not TRUE = FALSE
   FALSE xor TRUE = TRUE
   etc.

Regards,
   Juergen