What is semi-predicate? It sounds theoretical.
What is google? semi-predicate -> http://en.wikipedia.org/wiki/Semipredicate_problem
Simply it means return undef to signal failure, but it can return undef as valid value, so you can't differentiate between failure or just a valid value
It applies here because perl expects perl syntax, so you can't inline arbitrary text verbatim as part of a perl program, it could be a perl program, so you have to quote/escape, like
my $asCloseAsYouCanGet = <<'__TO_VERBATIM__';
other stuff not that is not __TO_VERBATIM__ on a single line
__TO_VERBATIM__
The text in $asCloseAsYouCanGet cannot contain __TO_VERBATIM__ on a single line as input, because __TO_VERBATIM__ on a single line is like the closing quote, it signals the end of the input, so it can't be valid input
In other words, the semi-predicate problem, it can't be both valid input and closing quote, it has to be one or the other, not both
Its like pictorial depictions of numbers, the symbol for the number one, 1, cannot be the same symbol for the number two, 1 , because you cannot tell when it means one or it means two
1 + 1 + 1 = 4? See the first 1 is really one, the second 1 is really two, and the last one is really 1 , which adds up to four
:) |