That's interesting, thanks. Am I correct in my (I'm not sure if it's a memory of something I read somewhere, or an assumption I have formed) that Perl will fold string constants?

From my (brief and un-expert) look at the byte code produced by javac, it seems to be pushing a new copy of the two constants onto the stack (they could be pointers to a single copy, I can't make up my mind) prior to the call to StringBuffer, at each invokation?

Whereas I assume that Perl would push a reference to a single copy of each.

Thinking about that, javac is probably pushing a pointer too.

Am I correct in my (I'm not sure if it's a memory of something I read somewhere, or an assumption I have formed) that Perl will fold string constants?

Apparently it does not.

perl -MO=Deparse,-q -e"print qq(I am $x\n) . 'and fold this?'"
[download]

it taken as

print(('I am ' . $x . "\n") . 'and fold this?');
[download]

not print('I am ' . $x . "\nand fold this?").

—John

True, but

perl -MO=Deparse,-q -e "print 'Hello, ' . 'World'"

Is parsed as

print 'Hello, World';
-e syntax OK
[download]

Apparently, the example you gave was more complex than the parser wanted to deal with.

Update Added -q, as John pointed out below...