#ObjectType1
Param1: 8
Param2: SomeText

#ObjectType1.NestedObject
Param1: 3
Param2: SomeText

#ObjectType1
...

#ObjectType2
...

##</code><code>##

ObjectType1
{
   Param1 = 8
   Param2 = SomeText
   NestedObject
   {
      Param1 = 3
      Param2 = SomeText
   }
}
ObjectType2
{
   ...
}
ObjectType1
{
   ...
}

##</code><code>##

use strict ;
use warnings ;

my $file = "test" ;

open (my $fhi, "<", $file . ".dat" ) or die "Cannot open $file.dat\n" ;
open (my $fho, ">", $file . "_out.dat" ) or die "Cannot open $file" . "_out.dat\n" ;

my $context = "" ;

while ( my $line = <$fhi> ) {
	chomp $line ;
	if ( $line =~ /ObjectType1/ ) {
		$context = "ObjectType1" ;
	}
	if ( $line =~ /$\}/ ) {
		$context = "" ;
	}
	if ( $context eq "ObjectType1" ) {
		if ( $line =~ /Param1/ ) {
			print $fho "Param1 = 0\n" ;
		} elsif ( $line =~ /Param2/ ) {
			print $fho "Param2 = SomeOtherText\n" ;
		} else {
			print $fho $line . "\n" ;
		}
	} else {
		print $fho $line . "\n" ;
	}
}