I should use a hash instead, but humor me, would you ?

Well, just this once :-)

Actually, it works for me on the command line if not using strictures and not declaring the variables so they default to being package variables.

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

Enabling strictures and using lexical varables throws a "strict refs" error

$ 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.
$
[download]

Turning the stricture off inside the print statement throws an "uninitialsed value" warning because you can't have soft references with lexical variables.

$ 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.
$
[download]

Declaring the variables as package variables with our gets things working again.

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

But having said all of that, you really should be using a hash and should avoid soft references like the plague if at all possible.

Cheers,

JohnGG