in reply to Re^2: Trying to understand closures
in thread Trying to understand closures

my $x does actually change the value of $x .

Update: That's wrong. I don't know why I wrote that. As far as I know my creates a new variable so the later references to $x actually refer to a different instance of a variable even though they have the same name.

For example this code: 
print __LINE__ . ": $x\n";
my $x = 123;
print __LINE__ . ": $x\n";
my $x = 456;
print __LINE__ . ": $x\n";
my $x;
print __LINE__ . ": $x\n";

[download]
Prints out: 
1: 
3: 123
5: 456
7:

[download]

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Re^4: Trying to understand closures
by ikegami (Patriarch) on Nov 24, 2006 at 05:54 UTC

    Each of those $x is a different variable. 

    "my" variable $x masks earlier declaration in same scope at 585826.pl 
+line 4.
"my" variable $x masks earlier declaration in same scope at 585826.pl 
+line 6.
print __LINE__ . ": " . \$x . " = $x \n";
my $x = 123;
print __LINE__ . ": " . \$x . " = $x \n";
my $x = 456;
print __LINE__ . ": " . \$x . " = $x \n";
my $x;
print __LINE__ . ": " . \$x . " = $x \n";

    [download]
    1: SCALAR(0x0225fc4) =
3: SCALAR(0x022603c) = 123
5: SCALAR(0x1830b1c) = 456
7: SCALAR(0x1830ba0) =

    [download]

    (Undefined warnings omitted.)

    Note that my $x does not always create a new variable. In my snippet, $x, $y and $z are the same variable every pass through the loop.

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