Re: Distinguishing between an array of objects and an array of strings

ref is true if its operand is a reference so you can test like this:

use warnings;
use strict;

my $str = 'Str';
my $rStr = \$str;
my $rrStr = \$rStr;

print "\$rrStr is ref to ref to str\n" if ref $rrStr and ref $$rrStr;
print "\$rStr is ref to str\n" if ref $rStr;
print "\$str is str\n" if ! ref $str;
[download]

Note that each additional $ dereferences by one.

Perl is Huffman encoded by design.

Comment on Re: Distinguishing between an array of objects and an array of strings Download Code

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Re^2: Distinguishing between an array of objects and an array of strings by tinita (Parson) on Sep 22, 2005 at 10:30 UTC
ref is true if its operand is a reference slightly different: `ref` returns the type of object ('ARRAY', 'SCALAR', or the classname). if the classname was '0' (zero), then ref would not be 'true'. ok, nobody would call their classes '0', just thought i should add that to clarify what ref does.	[reply] [d/l]
Re^3: Distinguishing between an array of objects and an array of strings by Zaxo (Archbishop) on Sep 22, 2005 at 11:49 UTC
ok, nobody would call their classes '0', . . . There is a good reason for that. $ perl -e'package 0' syntax error at -e line 1, near "package 0" Execution of -e aborted due to compilation errors. $ [download] Namespace names follow the same rules as variable names. After Compline, Zaxo	[reply] [d/l]
Re^4: Distinguishing between an array of objects and an array of strings by Anonymous Monk on Sep 22, 2005 at 12:41 UTC
`0` is a perfectly valid variable name. `$0` is a well known variable - and @0 and %0 are valid as well. `0` is also valid as a package name - but like many other valid package names, you can't use it as an argument to `package`.	[reply]
Re^4: Distinguishing between an array of objects and an array of strings by diotalevi (Canon) on Sep 22, 2005 at 14:31 UTC
No they don't. package declarations do, namespaces can be anything. `*{ anything } = \ anything; bless ..., anything;` [download]	[reply] [d/l]
Re^4: Distinguishing between an array of objects and an array of strings by friedo (Prior) on Sep 22, 2005 at 14:29 UTC
`my $pkg = "0"; my $o = bless { }, $pkg; print ref $o;` [download]	[reply] [d/l]
Re^3: Distinguishing between an array of objects and an array of strings by Anonymous Monk on Sep 22, 2005 at 10:45 UTC
Indeed, and unfortunally, if `$var` isn't a reference, `ref($var)` returns a false, but defined value, so testing for `defined ref($var)` is even worse than testing for `ref($var)`. However, it isn't possible to bless something into a package with no name, if the second argument of bless equals the empty string, the thing is blessed into `main. So, if ref returns anything but the empty string, its argument is a reference.`	[reply]