"Only perl can parse Perl"

• People are fond of saying this

• If you want to know what Perl will think of some program, you must ask perl itself

• No regex or other simple process will always produce the right answer

• This is because to parse Perl, you also have to be able to interpret Perl

• Bizarre but typical example:

        $t = time / 3;          # Is this a comment? /;

        $s =  sin / 3;          # Is this a comment? /;

• Now what about this?

        $u = blub / 3;          # Is this a comment? /;

• You need to know if blub is like time or like sin

Next

Copyright © 2003 M. J. Dominus