From 4fdebb8f8dda879531b39139969016e446c6abb5 Mon Sep 17 00:00:00 2001
From: lilo_booter <lilo_booter@d19143bc-622f-0410-bfdd-b5b2a6649095>
Date: Mon, 16 Aug 2004 06:48:51 +0000
Subject: [PATCH] Object validity checks

git-svn-id: https://mlt.svn.sourceforge.net/svnroot/mlt/trunk/mlt++@366 d19143bc-622f-0410-bfdd-b5b2a6649095
---
 mlt++/README                |    3 +++
 mlt++/src/MltProperties.cpp |    5 +++++
 mlt++/src/MltProperties.h   |    2 ++
 mlt++/test/play.cpp         |    7 ++++++-
 4 files changed, 16 insertions(+), 1 deletions(-)

diff --git a/mlt++/README b/mlt++/README
index 26cc441..f4e8bed 100644
--- a/mlt++/README
+++ b/mlt++/README
@@ -82,6 +82,9 @@ SPECIAL CASES
 	This excludes the use of the RTTI to determine the real type of the object -
 	this can only be done by parsing the objects properties.
 
+	Non-NULL objects may be invalid - always use the is_valid method to
+	check validity before use.
+
 LIMITATIONS
 -----------
 
diff --git a/mlt++/src/MltProperties.cpp b/mlt++/src/MltProperties.cpp
index 72dcba3..9558fcc 100644
--- a/mlt++/src/MltProperties.cpp
+++ b/mlt++/src/MltProperties.cpp
@@ -46,6 +46,11 @@ PropertiesInstance::~PropertiesInstance( )
 		mlt_properties_close( instance );
 }
 
+bool Properties::is_valid( )
+{
+	return get_properties( ) != NULL;
+}
+
 int Properties::count( )
 {
 	return mlt_properties_count( get_properties( ) );
diff --git a/mlt++/src/MltProperties.h b/mlt++/src/MltProperties.h
index c9429c1..51d0952 100644
--- a/mlt++/src/MltProperties.h
+++ b/mlt++/src/MltProperties.h
@@ -32,6 +32,7 @@ namespace Mlt
 	{
 		public:
 			virtual mlt_properties get_properties( ) = 0;
+			bool is_valid( );
 			int count( );
 			char *get( char *name );
 			int get_int( char *name );
@@ -41,6 +42,7 @@ namespace Mlt
 			int set( char *name, int value );
 			int set( char *name, double value );
 			int set( char *name, void *value, int size, mlt_destructor destroy = NULL, mlt_serialiser serial = NULL );
+
 	};
 	
 	/** Instance class.
diff --git a/mlt++/test/play.cpp b/mlt++/test/play.cpp
index 5920a4b..1707d05 100644
--- a/mlt++/test/play.cpp
+++ b/mlt++/test/play.cpp
@@ -11,9 +11,14 @@ using namespace Mlt;
 int main( int argc, char **argv )
 {
 	Factory::init( NULL );
+	Producer *producer = Factory::producer( argv[ 1 ] );
+	if ( !producer->is_valid( ) )
+	{
+		cerr << "Can't construct producer for " << argv[ 1 ] << endl;
+		return 0;
+	}
 	Consumer *consumer = Factory::consumer( "sdl" );
 	consumer->set( "rescale", "none" );
-	Producer *producer = Factory::producer( argv[ 1 ] );
 	Filter *filter = Factory::filter( "greyscale" );
 	filter->connect( *producer );
 	consumer->connect( *filter );
-- 
1.7.4.4