When in doubt, use B::Deparse. 
U:\proj>perl -MO=Deparse -e "print $a + $b"
print $a + $b;
-e syntax OK

U:\proj>perl -MO=Deparse -e "print $a +$b"
print $a $b;
-e syntax OK

[download]
As you can see, perl guesses from the whitespace after print and its first argument that you intended a unary plus, instead of an addition between arguments. It then decided that $a must be an object (like a file handle) for object indirect syntax.

Personally, I wish Deparse was even more clear about that: 

U:\proj>perl -MO=Deparse -e "print $a +$b"
$a->print $b;

[download]

--
[ e d @ h a l l e y . c c ]

In reply to Re: Print not printing by halley
in thread Print not printing by perl_lover

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