I've got this code: 
use strict;
use warnings;

{
 my $x = 0;
 sub X() {
   ++$x;
   \$x;
 }
}

print ${X()}, "\n";
print ${X()}, "\n";
print ${X()}, "\n";
print ${X()}, "\n";
print "${X()}${X()}\n";  # why does this behave
print "${X()} ${X()}\n"; # differently from this?

[download]
X() provides a reference to the its $x, and $x increases from 1,2,3, etc. But funny things happen when I have two X()'s in one statement. Sometimes it evaluates the two independently, so I get two different values, but sometimes it evaluates both of them to the same value. The output is: 
1
2
3
4
66      <--- why is this not 56?
7 8     <--- or why is this not 8 8?

[download]
What I can't explain is why the last two outputs have different values, since the only difference between them is the addition of a space in the string.

In reply to Order of evaluation/interpolation of references by Anonymous Monk

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