develooper Front page | perl.perl6.language | Postings from May 2005

Re: s/true/better name/

Thread Previous | Thread Next
From:
=?ISO-8859-1?Q?=22TSa_=28Thomas_Sandla=DF=29=22?=
Date:
May 24, 2005 09:11
Subject:
Re: s/true/better name/
Message ID:
4293521E.2040709@orthogon.com
Sorry, that I excavate that thread, but it just fits my question.

Rod Adams wrote:
> Well, "and" and "or" serve the purpose of being at a much lower 
> precedence level than "&&" and "||".
> 
> I would see the value in alphabetic "not" as serving the same relation 
> to "!". But I would still see it returning a Bool, not a numified 0 or 
> 1. I could see a "boolean" operator serving the same relation to "?".

The question is: are ?, !, not and true returning values besides the
boolean evaluation? Something like 'value but true'? To wit:

my $a = 4;
my $b = 0;

say 'true' if $a; # prints 'true'

say  $a  && $b;  # prints '4'
say ($a and $b); # same, parens needed for precedence

say 'true' if not $b; # prints 'true'

say not $a; # prints 0, or '4 but false'
say $b || not $a; # prints '4 but false'
say $b ||    !$a; # prints '4 but false'

say bit  $a; # prints '0' or 'false'
say bool $a; # print '4 but true'


> But for those cases where someone absolutely has to have a 1 or 0, not 
> some Boolean object, sticking a  "+"  or "int" in front of a "!", "?", 
> "not", or "boolean" seems to cover that case fine.

Boolean return values are the task of unary ?^, aren't they? Continuing
from above +?$a would still be 4 not bit::true, right? Even ~+?*+?$a is
as far as the value is concerned a no-op? Thus to really flatten away the
value one needs to use ?^ which has bit as the alpha pendant?

If my above assumptions are correct I would like to get bool as the
alpha pendant to ? like not for !. BTW are num and str the equivalents
of + and ~ respectively? And - has no corresponding neg or so? The strings
'true' and 'false' should really be kept as enums of the bit type.

Thanks for your patience with me.
-- 
TSa (Thomas SandlaƟ)


Thread Previous | Thread Next


nntp.perl.org: Perl Programming lists via nntp and http.
Comments to Ask Bjørn Hansen at ask@perl.org | Group listing | About