I would explain it slightly differently than BrowserUk.

$ perl -le 'my $a = "foo"; $a = \$a; print $a'
REF(0x7f9b608299c8)

In this example, a reference to  $a is assigned to  $a and the whole thing becomes circular; $a refers to $a, which refers to $a, ... So $a is a REF to $a (to $a, to ...) If the magical names  $a and  $b are avoided and everything is made lexical to keep everyone honest and aboveboard (nothing up my sleeve...): 

c:\@Work\Perl\monks>perl -wMstrict -le
"my $x = 'foo';
 $x = \$x;
 print $x;
 print $$x;
 print $$$x;
 print $$$$x;
"
REF(0x1df2a9c)
REF(0x1df2a9c)
REF(0x1df2a9c)
REF(0x1df2a9c)

[download]
Note that the reference addresses are all the same.

$ perl -le 'my $a = "foo"; my $b = \$a; $a = $b; print $a'
REF(0x7fab830299c8)

This example is a bit more roundabout in that it first assigns a reference to  $a to another scalar before assigning it back to  $a to establish circularity, but the result is the same: 

c:\@Work\Perl\monks>perl -wMstrict -le
"my $x = 'foo';
 my $y = \$x;
 $x = $y;
 print $x;
 print $$x;
 print $$$x;
 print $$$$x;
"
REF(0x601cec)
REF(0x601cec)
REF(0x601cec)
REF(0x601cec)

[download]
Again, all the reference addresses are the same.

In all these examples, the original value of $x (or $a in the OPed code), 'foo', is lost.

Update: Or entirely without circularity: 

c:\@Work\Perl\monks>perl -wMstrict -MData::Dump -le
"my $w = 'foo';
 my $x = \$w;
 my $y = \$x;
 my $z = \$y;
 ;;
 print $z;
 print $$z;
 print $$$z;
 print $$$$z;
 ;;
 dd $z;
"
REF(0x54c11c)
REF(0x432734)
SCALAR(0x4326f4)
foo
\\\"foo"

[download]

Give a man a fish:  <%-{-{-{-<

In reply to Re: Why do I (sometimes) get a REF ref and not a SCALAR ref? by AnomalousMonk
in thread Why do I (sometimes) get a REF ref and not a SCALAR ref? by Anonymous Monk

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