cpp can set enums from strings

eg.

	set("extend", "copy")->

ChangeLog

@@ -1,3 +1,6 @@
+30/12/14 started 7.42.2
+- allow c++ set enum from string
+
 24/12/14 started 7.42.1
 - add gobject-2.0 to Requires: in vips and vips-cpp .pc files
 - bump soname

TODO

@@ -1,3 +1,34 @@
+- display of optional params should show default value
+
+  also display possible enum values?
+
+  min and max for int/float params?
+
+  maybe:
+
+$ vips embed
+embed an image in a larger image
+usage:
+   embed in out x y width height
+where:
+   in           - Input image, input VipsImage
+   out          - Output image, output VipsImage
+   x            - Left edge of input in output, input gint
+   			(default: 0, min: -inf, max: inf)
+   y            - Top edge of input in output, input gint
+   			(default: 0, min: -inf, max: inf)
+   width        - Image width in pixels, input gint
+   			(default: 100, min: 0, max: inf)
+   height       - Image height in pixels, input gint
+   			(default: 100, min: 0, max: inf)
+optional arguments:
+   extend       - How to generate the extra pixels, input VipsExtend
+   			(default: black, allowed: copy, extend, mirror)
+   background   - Colour for background pixels, input VipsArrayDouble
+   			(default: 0, min: 0, max: inf)
+operation flags: sequential-unbuffered 
+
+
 - use vips_resize() in vipsthumbnail?
 
   should the sharpening filter be selectable?

configure.ac

@@ -2,7 +2,7 @@
 
 # also update the version number in the m4 macros below
 
-AC_INIT([vips], [7.42.1], [vipsip@jiscmail.ac.uk])
+AC_INIT([vips], [7.42.2], [vipsip@jiscmail.ac.uk])
 # required for gobject-introspection
 AC_PREREQ(2.62)
 
@@ -18,7 +18,7 @@ AC_CONFIG_MACRO_DIR([m4])
 # user-visible library versioning
 m4_define([vips_major_version], [7])
 m4_define([vips_minor_version], [42])
-m4_define([vips_micro_version], [1])
+m4_define([vips_micro_version], [2])
 m4_define([vips_version],
           [vips_major_version.vips_minor_version.vips_micro_version])
 
@@ -38,7 +38,7 @@ VIPS_VERSION_STRING=$VIPS_VERSION-`date`
 #   binary interface changes not backwards compatible?: reset age to 0
 
 LIBRARY_CURRENT=40
-LIBRARY_REVISION=0
+LIBRARY_REVISION=1
 LIBRARY_AGE=0
 
 # patched into include/vips/version.h

cplusplus/VImage.cpp

@@ -1,4 +1,8 @@
-// Object part of VImage class
+/* Object part of VImage class
+ *
+ * 30/12/14
+ * 	- allow set enum value from string
+ */
 
 /*
 
@@ -327,6 +331,47 @@ VOption::set( const char *name, VipsBlob **value )
 	return( this );
 }
 
+// just g_object_set_property(), except we allow set enum from string
+static void 
+set_property( VipsObject *object, const char *name, const GValue *value )
+{
+	VipsObjectClass *object_class = VIPS_OBJECT_GET_CLASS( object );
+	GType type = G_VALUE_TYPE( value );
+
+	GParamSpec *pspec;
+	VipsArgumentClass *argument_class;
+	VipsArgumentInstance *argument_instance;
+
+	if( vips_object_get_argument( object, name, 
+		&pspec, &argument_class, &argument_instance ) ) {
+		vips_warn( NULL, "%s", vips_error_buffer() );
+		vips_error_clear();
+		return;
+	}
+
+	if( G_IS_PARAM_SPEC_ENUM( pspec ) &&
+		type == G_TYPE_STRING ) {
+		GType pspec_type = G_PARAM_SPEC_VALUE_TYPE( pspec );
+
+		int enum_value;
+		GValue value2 = { 0 }; 
+
+		if( (enum_value = vips_enum_from_nick( object_class->nickname, 
+			pspec_type, g_value_get_string( value ) )) < 0 ) {
+			vips_warn( NULL, "%s", vips_error_buffer() );
+			vips_error_clear();
+			return;
+		}
+
+		g_value_init( &value2, pspec_type ); 
+		g_value_set_enum( &value2, enum_value ); 
+		g_object_set_property( G_OBJECT( object ), name, &value2 );
+		g_value_unset( &value2 );
+	}
+	else
+		g_object_set_property( G_OBJECT( object ), name, value );
+}
+
 // walk the options and set props on the operation 
 void 
 VOption::set_operation( VipsOperation *operation )
@@ -343,7 +388,7 @@ VOption::set_operation( VipsOperation *operation )
 			g_free( str_value );
 #endif /*VIPS_DEBUG_VERBOSE*/
 
-			g_object_set_property( G_OBJECT( operation ),
+			set_property( VIPS_OBJECT( operation ),
 				(*i)->name, &(*i)->value );
 		}
 }

doc/reference/using-cpp.xml

@@ -73,7 +73,7 @@ main( int argc, char **argv )
 
   VImage out = in.embed( 10, 10, 1000, 1000, 
     VImage::option()->
-      set( "extend", VIPS_EXTEND_BACKGROUND )->
+      set( "extend", "background" )->
       set( "background", 128 ) );
 
   out.write_to_file( argv[2] );
@@ -113,7 +113,9 @@ main( int argc, char **argv )
           <para>
             In this case we request unbuffered IO for the image, meaning, we 
             expect to do a single top-to-bottom scan of the image and do not 
-            need it to be decompressed entirely. 
+            need it to be decompressed entirely. You can use the C enum name, 
+            as is done in this case, or use a string and have the string 
+            looked up. See below.
           </para>
 
           <para>
@@ -197,7 +199,9 @@ VImage VImage::add( VImage right, VOption *options = 0 );
 
     <para>
       The next line runs vips_embed() with two optional parameters. The first 
-      sets the value to an enum (you just use the ones from the C API), the 
+      sets the value to an enum (here we use a string to set the value, it'll 
+      be looked up in the list of possible enum values, or you can use the 
+      symbols from the C API), the 
       second sets the value to an <code>int</code>. The 
       <code>"background"</code> 
       parameter is actually a #VipsArrayDouble: if you pass an 

libvips/iofuncs/error.c

@@ -206,7 +206,8 @@ vips_verror( const char *domain, const char *fmt, va_list ap )
 	g_mutex_lock( vips__global_lock );
 	g_assert( vips_error_freeze_count >= 0 );
 	if( !vips_error_freeze_count ) {
-		vips_buf_appendf( &vips_error_buf, "%s: ", domain );
+		if( domain ) 
+			vips_buf_appendf( &vips_error_buf, "%s: ", domain );
 		vips_buf_vappendf( &vips_error_buf, fmt, ap );
 		vips_buf_appends( &vips_error_buf, "\n" );
 	}