This section provides a tutorial example on how to use symbolic references by replacing identifiers with any string expressions, like ${EXPR}.
As mentioned in the previous section,
if a variable or function identifier is presented by a string expression,
the string expression can be placed in curly brackets {}
to replace the identifier. Curly brackets are also called lookups. String literals
in lookups don't have to be quoted.
The following tutorial program shows you some interesting examples. In the first group, I used
scalar variables in the lookups. In the second group, I used some string literals and
expressions in the lookups. In the third group, I used array elements, hash elements
and function returns in the lookups.
#- SoftRef2.pl
#- Copyright (c) 1999 by Dr. Herong Yang, http://www.herongyang.com/
#
$name = 'foo';
@name = ('foo');
%name = ('i', 'foo');
${$name} = 10; print "$foo\n"; # the scalar of $foo
@{$name} = (20); print "$foo[0]\n"; # entire array of @foo
${$name}[0] = 30; print "$foo[0]\n"; # an element of @foo
@{$name}[0] = (40); print "$foo[0]\n"; # a slice of @foo
%{$name} = ('k',50); print "$foo{k}\n"; # entire hash of %foo
${$name}{'k'} = 60; print "$foo{k}\n"; # an element of %foo
@{$name}{'k'} = (70); print "$foo{k}\n"; # a slice of %foo
&{$name}(80); # calling &foo
${foo} = 110; print "$foo\n";
@{'foo'} = (120); print "$foo[0]\n";
${"foo"}[0] = 130; print "$foo[0]\n";
@{'f'.'oo'}[0] = (140); print "$foo[0]\n";
%{foo} = ('k',150); print "$foo{k}\n";
${'foo'}{'k'} = 160; print "$foo{k}\n";
@{"foo"}{'k'} = (170); print "$foo{k}\n";
&{'f'.'oo'}(180);
${$name[0]} = 210; print "$foo\n";
@{$name{'i'}} = (220); print "$foo[0]\n";
${&name}[0] = 230; print "$foo[0]\n";
@{$name[0]}[0] = (240); print "$foo[0]\n";
%{$name{'i'}} = ('k',250); print "$foo{k}\n";
${&name}{'k'} = 260; print "$foo{k}\n";
@{$name[0]}{'k'} = (270); print "$foo{k}\n";
&{$name{'i'}}(280);
sub foo {print "$_[0]\n";}
sub name {return 'foo';}
