Question

I am kinda beginner in perl and I need know how can I check object class name.

My code is:

 foreach my $y (keys %$x) {
   print "$y\t$x->{$y}\n";
 }

with output:

154176568       [object HTMLImageElement]
146292140       [object HTMLDocument]
153907016       [object HTMLImageElement]

I need to print just keys that are HTMLImageElement objects.

Now, question is:

(1) How can I check the class name

(2) How can I get/print class name

Answer 1

Looking at the source for JE, it looks like JE::Object::Proxy is a subclass of JE::Object, and JE::Object has a stringification method (use overload fallback => 1, ... '""' => 'to_string' ...).

So when you do print "$y\t$x->{$y}\n";, this is printing the result of stringifying $x->{$y}.

You can stringify the object by putting it in double quotes, so "$x->{$y}". This expression will then have values such as you saw being printed, e.g. '[object HTMLImageElement]'.

If you want to pick up only HTMLImageElement objects, then you could check for these using an expression like

"$x->{$y}" eq '[object HTMLImageElement]'

If you especially want to extract the string 'HTMLImageElement' from the stringified value, you could do that using a regexp, e.g.

("$x->{$y}" =~ m{^\[object (.*)\]$}so)[0]

THOUGH, looking at the source for JE::Object::Proxy, JE::Object::Proxy has a method class which might perhaps return the name of the class that the object is a proxy for. So you might be able to get the class name using $x->{$y}->class, and then be able to test that directly as in $x->{$y}->class eq 'HTMLImageElement'.