in reply to Re: A more concise way to map the contents of an array.
in thread A more concise way to map the contents of an array.

I like the first one you wrote, i hadn't come across that operator. Seems exactly the same as a conditional statement in Verilog. So it's still pretty readable to me!

Regarding your footnote, supposing i didn't need 0 for false, how would i do it? And how else can you represent false?

Thanks very much for your very helpful reply.

  • Comment on Re^2: A more concise way to map the contents of an array.

Replies are listed 'Best First'.
Re^3: A more concise way to map the contents of an array.
by LanX (Saint) on Dec 30, 2012 at 13:55 UTC
    > Regarding your footnote, supposing i didn't need 0 for false, how would i do it? And how else can you represent false?

    Just use the product of a doubled negation to get clear booleans!¹

    Perl's definition of false covers different data types and context cases.

    from perldata

           A scalar value is interpreted as TRUE in the Boolean sense if i
+t is not
       the null string or the number 0 (or its string equivalent, "0")
+.  The
       Boolean context is just a special kind of scalar context where 
+no
       conversion to a string or a number is ever performed.

    [download]

    (Null string here means either empty string "" or undef)

    from perlsyn

    Truth and Falsehood
 
       The number 0, the strings '0' and '', the empty list "()", and 
+"undef"
       are all false in a boolean context. All other values are true.
       Negation of a true value by "!" or "not" returns a special fals
+e value.
       When evaluated as a string it is treated as '', but as a number
+, it is
       treated as 0.

    [download]

    Cheers Rolf

    ¹) in this case  my @cell_contents = map { !!$_ } @$array_ref[3..10];

    for me the most readable alternative!

[reply]
[d/l]
[select]

      So just to be clear, if i double negate something, i'll lose the original "value" and be left with the pure boolean representation of the data? That could prove useful!

      Thanks again for your reply!

[reply]
[reply]
        Yes ... negating means evaluating in boolean context!

        (well "pure"¹ is a risky adjective in the sphere of Perl's DWIM flexibility ... ;)

        Anyway if this approach ever fails it certainly is a bug!

        EDIT:

        IMHO people prefer using 0 for false because it's easier to print and read than an empty string. But technically this is not necessary.

        Cheers Rolf

        ¹) lets say "well-defined"!

[reply]

In Section Seekers of Perl Wisdom