$ perl -le '
> $foo = q{foo};
> $bar = q{f};
> print ${$bar . q{oo}};'
foo
$

##</code><code>##

$ perl -Mstrict -wle '
> my $foo = q{foo};
> my $bar = q{f};
>  print ${$bar . q{oo}};'
Can't use string ("foo") as a SCALAR ref while "strict refs" in use at -e line 4.
$

##</code><code>##

$ perl -Mstrict -wle '
> my $foo = q{foo};
> my $bar = q{f};
> print do {no strict q{refs}; ${$bar . q{oo}} };'
Use of uninitialized value in print at -e line 4.
$

##</code><code>##

$ perl -Mstrict -wle '
> our $foo = q{foo};
> our $bar = q{f};
> print do {no strict q{refs}; ${$bar . q{oo}} };'
foo
$