How can I extract all global variables from a script and get each data type in Perl? - perl

Question

I like to capture all global variables from an external Perl script with Perl. Currently I am hanging around the type detection.
How to determine the correct data type ('', 'SCALAR', 'HASH', 'ARRAY', 'CODE')?
Parser script:
my %allVariables = ();
{
do "scriptToBeParsed.pl";
foreach my $sym ( keys %main:: ) {
# Get all normal variables and scalar/hash/array references:
if ( ref( *{"$sym"} ) =~ m/^(?:|SCALAR|HASH|ARRAY)$/ ) {
$allVariables{"$sym"} = *{"$sym"};
}
}
}
Script to be parsed:
$someVariable1 = 'Yes, I like to be captured';
$otherVariable2 = \'And I also want to be captured';
%anotherVariable3 = ( 'Capture' => 'me' );
#lameVariable4 = ( 'Capture', 'me' );
$fooVariable5 = { 'Capture' => 'me' };
$barVariable6 = [ 'Capture', 'me' ];
$subVariable7 = sub { return "Don't capture me!" };
sub dontCaptureMe { return "Don't capture me!" }
In my example ref( *{"$sym"} ) returns always 'GLOB' (of course).

Answer 1

Another approach would be to use the has-like access of the typeglob, which is explained in Chapter 8 of brian d foy's Mastering Perl on page 131f.
package test;
no strict;
no warnings;
$someVariable1 = 'Yes, I like to be captured';
$otherVariable2 = \'And I also want to be captured';
%anotherVariable3 = ( 'Capture' => 'me' );
#lameVariable4 = ( 'Capture', 'me' );
$fooVariable5 = { 'Capture' => 'me' };
$barVariable6 = [ 'Capture', 'me' ];
$subVariable7 = sub { return "Don't capture me!" };
sub dontCaptureMe { return "Don't capture me!" }
say $dontCaptureMe;
my %allVariables = ();
{
do "scriptToBecomeParsed.pl";
foreach my $sym ( keys %test:: ) {
for (qw( SCALAR HASH ARRAY CODE IO)) {
if (*{"$sym"}{$_}) {
$allVariables{$_}->{"$sym"} = *{"$sym"}{$_};
}
}
}
}
print Data::Dumper::Dumper \%allVariables;
This will produce the following output:
$VAR1 = {
'CODE' => {
'dontCaptureMe' => sub { "DUMMY" }
},
'ARRAY' => {
'lameVariable4' => [
'Capture',
'me'
]
},
'HASH' => {
'anotherVariable3' => {
'Capture' => 'me'
}
},
'SCALAR' => {
'someVariable1' => \'Yes, I like to be captured',
'__ANON__' => \undef,
'subVariable7' => \sub { "DUMMY" },
'dontCaptureMe' => \undef,
'otherVariable2' => \\'And I also want to be captured',
'BEGIN' => \undef,
'barVariable6' => \[
'Capture',
'me'
],
'anotherVariable3' => \undef,
'lameVariable4' => \undef,
'fooVariable5' => \{
'Capture' => 'me'
}
}
};

Answer 2

like you said
ref( *{"$sym"} ) returns always 'GLOB' (of course).
Because perl stores everything in the symbol table in a glob, it is impossible to tell which data type something is. This is because in perl it is perfectly valid to have an array, scalar, hash or whatever else with the same name... because of this, perl stores everything in globs to avoid collisions. What you could do is loop through all of the symbols in the symbol table and test each glob against all the possible things that it could be (the set isn't too large) and see which ones are set.
Alternatively, a more practical approach might be to just load the perl script as text and parse for $, %, #, sub, open (filehandle) to see what type everything is.