- Added the Block.pfork() method which works almost identical with th…

…e Perl fork() function -- it doesn't create a temporary file with the result of the computation, but it still returns a Fork object.

Example:
	var f = { say "hello" }.pfork;
	f.wait;

lib/Sidef/Types/Block/Code.pm

@@ -351,6 +351,22 @@ package Sidef::Types::Block::Code {
         $fork;
     }
 
+    sub pfork {
+        my ($self) = @_;
+
+        my $fork = Sidef::Types::Block::Fork->new();
+
+        my $pid = fork() // die "[FATAL ERROR]: cannot fork";
+        if ($pid == 0) {
+            srand();
+            $self->run;
+            exit 0;
+        }
+
+        $fork->{pid} = $pid;
+        $fork;
+    }
+
     sub thread {
         my ($self) = @_;
         state $x = do {

lib/Sidef/Types/Block/Fork.pm

@@ -10,12 +10,13 @@ package Sidef::Types::Block::Fork {
     sub get {
         my ($self) = @_;
 
-        exists($self->{result})
-          or return;
-
         # Wait for the process to finish
         waitpid($self->{pid}, 0);
 
+        # Return when the fork doesn't hold a result
+        exists($self->{result})
+          or return;
+
         state $x = require Storable;
         my $ref = eval { Storable::retrieve($self->{result}) };
         unlink(delete $self->{result});