This would work:

( my $test ) 
  ? print 'c'
  : sub { print 'a'; print 'b' }->();
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But this is probably what you want:

( my $test ) 
  ? print 'c'
  : do{ print 'a'; print 'b' };
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There must be something I didnt understand yet, so I excuse my question, dear Monks. But why would anyone would like to do that? Is there any possibility, that

my $test
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may fail?

It seems to me like writing

if (1) {
   print "some";
} else {
   print "thing";
}
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(And in that case, I could imagine some kind of debug-switch or so).

Please enlighten me.

Is there any possibility, that my $test may fail?

Actually, it will always "fail". That is, an uninitialised variable is always undef, and therefore false.

It also doesn't make much sense to do print 'a'; print 'b'; instead of print 'a', 'b'; or print 'ab';.

I think it is fair to assume that the code supplied it greatly simplified example and that ( my $test ) is just a placeholder for 'some boolean condition' rather than an actual variable declaration.

---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

The statement…

( my $test ) 
  ? print 'c'
  : do{ print 'a'; print 'b' };
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…is much better written…

print 'a';
print 'b';
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No shit Sherlock!

---

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

The difference between the two is that in the first example, you are creating an anonymous subroutine and not saving a reference to it so you'll never be able to access it. The second example is running a named subroutine, which is perfectly legitimate.

  sub { print 'a'; print 'b' }
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You're not assigning the result of this constructor to anything, which is the "void context" part.

So Perl is saying "you made an anonymous sub reference and then you threw it away. Did you actually want to do that?"

hisham@bioslayer:~$ perl -
my $subref = sub{print 'a',"\n";};
(my $test)?print 'c' : $subref->(); #dereference with infix arrow oper
+ator
__END__
a
hisham@bioslayer:~$ perl -
my $subref = sub{print 'a',"\n"};
(my $test)?print 'c' : &{$subref}; #dereference with &{}
__END__
a
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First, Perl's conditional operator is a ternary operator, but it's called "conditional operator," not "ternary operator." The "conditional operator" is a specific operator; "ternary operator" describes a kind of operator.

Use the conditional operator only for conditional statements that return a single result—one scalar, list, hash, reference, etc.—and use it only for what it returns. In general, use it mostly for assigments to variables. Don't put program behavior—actions—inside the return-this parts of conditional operators. For that, use if-then-else statements instead. Your code will be more readable, more understandable, and more maintainable.

So…

my $test_result = <some test that returns a Boolean value>;
print $test_result ? qw( c ) : qw( a b );
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…or, better…

my $test_result = <some test that returns a Boolean value>;
my @values = $test_result ? qw( c ) : qw( a b );
print @values;
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