diff --git a/ChangeLog b/ChangeLog
index aa041814..f1ae7235 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -28,6 +28,8 @@
 - added string->double transform for cmdline args
 - merged class-params branch back into trunk
 - IM_FREE() can do "const char*" variables
+- im_buf_t renamed as VipsBuf
+- added vips_object_to_string()
 
 11/9/08 started 7.16.3
 - oop typo in manpage for im_project()
diff --git a/TODO b/TODO
index 2b8b53aa..383637be 100644
--- a/TODO
+++ b/TODO
@@ -1,3 +1,6 @@
+
+
+
 - try making vips_add(), an operator as a class
 
 - nickname, description etc need to be properties so nip2 can read them
@@ -13,7 +16,7 @@
 - update format docs
 
 - how to expose things like yafrsmooth's "sharpening" parameter to
-  nip2/C++/Python?
+  C++/Python?
 
   can we write a find-by-nickname function? eg.
 
@@ -25,24 +28,8 @@
 
   would get us the GType for VipsInterpolatorBicubic
 
-  add a g_get_children( "classname" ) -> ["child1-name", ..] to nip2, see old 
-  vips8.c code?
-
-  in nip2, 
-
-  	inter = g_object_new "yafrsmooth" [$sharpness => 2.4];
-
-  also need something to return a list of GTypes below a name etc., find class
-  description:w
-
-  need k
-
 - vips_object_print, set_name etc. need writing
 
-- im_buf_t -> VipsBuf
-
-  now always included in vips.h
-
 - check mosaic1, global_balance, similarity etc. use of im__affine
   
   how can we move them to im_affinei ?
diff --git a/include/vips/buf.h b/include/vips/buf.h
index 54f8b668..45476e34 100644
--- a/include/vips/buf.h
+++ b/include/vips/buf.h
@@ -27,58 +27,59 @@
 
  */
 
-#ifndef IM_BUF_H
-#define IM_BUF_H
+#ifndef VIPS_BUF_H
+#define VIPS_BUF_H
 
 #ifdef __cplusplus
 extern "C" {
 #endif /*__cplusplus*/
 
 /* A string in the process of being written to ... multiple calls to 
- * buf_append add to it, on overflow append "..." and block further writes.
+ * vips_buf_append add to it, on overflow append "..." and block further writes.
  */
 typedef struct {
-        char *base;             /* String base */
-        int mx;                 /* Maximum length */
-        int i;                  /* Current write point */
-        gboolean full;          /* String has filled, block writes */
-        int lasti;              /* For read-recent */
-        gboolean dynamic;       /* We own the string with malloc() */
-} im_buf_t;
+	char *base;		/* String base */
+	int mx;			/* Maximum length */
+	int i;			/* Current write point */
+	gboolean full;		/* String has filled, block writes */
+	int lasti;		/* For read-recent */
+	gboolean dynamic;	/* We own the string with malloc() */
+} VipsBuf;
 
 /* Static init of one of these.
  */
-#define IM_BUF_STATIC( TEXT, MAX ) \
-        { &TEXT[0], MAX, 0, FALSE, 0, FALSE }
+#define VIPS_BUF_STATIC( TEXT, MAX ) \
+	{ &TEXT[0], MAX, 0, FALSE, 0, FALSE }
 
-void im_buf_rewind( im_buf_t *buf );
-void im_buf_destroy( im_buf_t *buf );
-void im_buf_init( im_buf_t *buf ); 
-void im_buf_set_static( im_buf_t *buf, char *base, int mx );
-void im_buf_set_dynamic( im_buf_t *buf, int mx );
-void im_buf_init_static( im_buf_t *buf, char *base, int mx );
-void im_buf_init_dynamic( im_buf_t *buf, int mx );
-gboolean im_buf_appendns( im_buf_t *buf, const char *str, int sz );
-gboolean im_buf_appends( im_buf_t *buf, const char *str );
-gboolean im_buf_appendline( im_buf_t *buf, const char *str );
-gboolean im_buf_appendf( im_buf_t *buf, const char *fmt, ... )
+/* Init and append to one of the above.
+ */
+void vips_buf_rewind( VipsBuf *buf );
+void vips_buf_destroy( VipsBuf *buf );
+void vips_buf_init( VipsBuf *buf );
+void vips_buf_set_static( VipsBuf *buf, char *base, int mx );
+void vips_buf_set_dynamic( VipsBuf *buf, int mx );
+void vips_buf_init_static( VipsBuf *buf, char *base, int mx );
+void vips_buf_init_dynamic( VipsBuf *buf, int mx );
+gboolean vips_buf_appendns( VipsBuf *buf, const char *str, int sz );
+gboolean vips_buf_appends( VipsBuf *buf, const char *str );
+gboolean vips_buf_appendf( VipsBuf *buf, const char *fmt, ... )
 	__attribute__((format(printf, 2, 3)));
-gboolean im_buf_vappendf( im_buf_t *buf, const char *fmt, va_list ap );
-gboolean im_buf_appendc( im_buf_t *buf, char ch );
-gboolean im_buf_appendg( im_buf_t *buf, double g );
-gboolean im_buf_appendsc( im_buf_t *buf, const char *str );
-gboolean im_buf_removec( im_buf_t *buf, char ch );
-gboolean im_buf_change( im_buf_t *buf, const char *old, const char * );
-gboolean im_buf_isempty( im_buf_t *buf );
-gboolean im_buf_isfull( im_buf_t *buf );
-const char *im_buf_all( im_buf_t *buf );
-gboolean im_buf_appendd( im_buf_t *buf, int d );
-int im_buf_len( im_buf_t *buf );
+gboolean vips_buf_vappendf( VipsBuf *buf, const char *fmt, va_list ap );
+gboolean vips_buf_appendc( VipsBuf *buf, char ch );
+gboolean vips_buf_appendsc( VipsBuf *buf, gboolean quote, const char *str );
+void vips_buf_appendgv( VipsBuf *buf, GValue *value );
+gboolean vips_buf_removec( VipsBuf *buf, char ch );
+gboolean vips_buf_change( VipsBuf *buf, const char *old, const char * );
+gboolean vips_buf_is_empty( VipsBuf *buf );
+gboolean vips_buf_is_full( VipsBuf *buf );
+const char *vips_buf_all( VipsBuf *buf );
+const char *vips_buf_firstline( VipsBuf *buf );
+gboolean vips_buf_appendg( VipsBuf *buf, double g );
+gboolean vips_buf_appendd( VipsBuf *buf, int d );
+int vips_buf_len( VipsBuf *buf );
+
+#endif /*VIPS_BUF_H*/
 
 #ifdef __cplusplus
 }
 #endif /*__cplusplus*/
-
-#endif /*IM_BUF_H*/
-
-
diff --git a/include/vips/object.h b/include/vips/object.h
index 3190d6cd..23d252f9 100644
--- a/include/vips/object.h
+++ b/include/vips/object.h
@@ -196,11 +196,11 @@ struct _VipsObjectClass {
 
 	/* Try to print something about the class, handy for help displays.
 	 */
-	void (*print_class)( struct _VipsObjectClass *, im_buf_t * );
+	void (*print_class)( struct _VipsObjectClass *, VipsBuf * );
 
 	/* Try to print something about the object, handy for debugging.
 	 */
-	void (*print)( VipsObject *, im_buf_t * );
+	void (*print)( VipsObject *, VipsBuf * );
 
 	/* Class nickname, eg. "VipsInterpolateBicubic" has "bicubic" as a
 	 * nickname. Not internationalised. 
@@ -236,6 +236,7 @@ void vips_object_class_install_argument( VipsObjectClass *,
 	GParamSpec *pspec, VipsArgumentFlags flags, guint offset );
 
 VipsObject *vips_object_new_from_string( const char *base, const char *str );
+void vips_object_to_string( VipsObject *object, VipsBuf *buf );
 
 #ifdef __cplusplus
 }
diff --git a/libsrc/format/format.c b/libsrc/format/format.c
index 0aba31f0..e889f5d6 100644
--- a/libsrc/format/format.c
+++ b/libsrc/format/format.c
@@ -84,7 +84,7 @@ vips_format_map( VSListMap2Fn fn, void *a, void *b )
 G_DEFINE_ABSTRACT_TYPE( VipsFormat, vips_format, VIPS_TYPE_OBJECT );
 
 static void
-vips_format_print_class( VipsObjectClass *object_class, im_buf_t *buf )
+vips_format_print_class( VipsObjectClass *object_class, VipsBuf *buf )
 {
 	VipsFormatClass *class = VIPS_FORMAT_CLASS( object_class );
 	const char **p;
@@ -92,24 +92,24 @@ vips_format_print_class( VipsObjectClass *object_class, im_buf_t *buf )
 	VIPS_OBJECT_CLASS( vips_format_parent_class )->
 		print_class( object_class, buf );
 
-	im_buf_appends( buf, ", (" );
+	vips_buf_appends( buf, ", (" );
 	for( p = class->suffs; *p; p++ ) {
-		im_buf_appendf( buf, "%s", *p );
+		vips_buf_appendf( buf, "%s", *p );
 		if( p[1] )
-			im_buf_appends( buf, ", " );
+			vips_buf_appends( buf, ", " );
 	}
-	im_buf_appends( buf, ") " );
+	vips_buf_appends( buf, ") " );
 	
 	if( class->is_a )
-		im_buf_appends( buf, "is_a " );
+		vips_buf_appends( buf, "is_a " );
 	if( class->header )
-		im_buf_appends( buf, "header " );
+		vips_buf_appends( buf, "header " );
 	if( class->load )
-		im_buf_appends( buf, "load " );
+		vips_buf_appends( buf, "load " );
 	if( class->save )
-		im_buf_appends( buf, "save " );
+		vips_buf_appends( buf, "save " );
 	if( class->get_flags )
-		im_buf_appends( buf, "get_flags " );
+		vips_buf_appends( buf, "get_flags " );
 }
 
 static void
diff --git a/libsrc/format/im_jpeg2vips.c b/libsrc/format/im_jpeg2vips.c
index f717cbd3..02a43fe8 100644
--- a/libsrc/format/im_jpeg2vips.c
+++ b/libsrc/format/im_jpeg2vips.c
@@ -247,16 +247,16 @@ static void
 attach_exif_entry( ExifEntry *entry, IMAGE *im )
 {
 	char name_text[256];
-	im_buf_t name;
+	VipsBuf name;
 	char value_text[256];
-	im_buf_t value;
+	VipsBuf value;
 	char exif_value[256];
 
-	im_buf_init_static( &name, name_text, 256 );
-	im_buf_init_static( &value, value_text, 256 );
+	vips_buf_init_static( &name, name_text, 256 );
+	vips_buf_init_static( &value, value_text, 256 );
 
-	im_buf_appendf( &name, "exif-%s", exif_tag_get_title( entry->tag ) );
-	im_buf_appendf( &value, "%s (%s, %d bytes)", 
+	vips_buf_appendf( &name, "exif-%s", exif_tag_get_title( entry->tag ) );
+	vips_buf_appendf( &value, "%s (%s, %d bytes)", 
 		exif_entry_get_value( entry, exif_value, 256 ),
 		exif_format_get_name( entry->format ),
 		entry->size );
@@ -264,7 +264,7 @@ attach_exif_entry( ExifEntry *entry, IMAGE *im )
 	/* Can't do anything sensible with the error return.
 	 */
 	(void) im_meta_set_string( im, 
-		im_buf_all( &name ), im_buf_all( &value ) );
+		vips_buf_all( &name ), vips_buf_all( &value ) );
 }
 
 static void
diff --git a/libsrc/format/im_magick2vips.c b/libsrc/format/im_magick2vips.c
index 90e3db4b..5e96296b 100644
--- a/libsrc/format/im_magick2vips.c
+++ b/libsrc/format/im_magick2vips.c
@@ -338,11 +338,11 @@ parse_header( Read *read )
 	#error attributes enabled, but no access funcs found
 #endif
 		char name_text[256];
-		im_buf_t name;
+		VipsBuf name;
 
-		im_buf_init_static( &name, name_text, 256 );
-		im_buf_appendf( &name, "magick-%s", attr->key );
-		im_meta_set_string( im, im_buf_all( &name ), attr->value );
+		vips_buf_init_static( &name, name_text, 256 );
+		vips_buf_appendf( &name, "magick-%s", attr->key );
+		im_meta_set_string( im, vips_buf_all( &name ), attr->value );
 
 #ifdef DEBUG
 		printf( "key = \"%s\", value = \"%s\"\n", 
diff --git a/libsrc/iofuncs/buf.c b/libsrc/iofuncs/buf.c
index d0cf312c..21bd20b2 100644
--- a/libsrc/iofuncs/buf.c
+++ b/libsrc/iofuncs/buf.c
@@ -54,7 +54,7 @@
 #define MAX_STRSIZE (16000)
 
 void
-im_buf_rewind( im_buf_t *buf )
+vips_buf_rewind( VipsBuf *buf )
 {
 	buf->i = 0;
 	buf->lasti = 0;
@@ -67,64 +67,61 @@ im_buf_rewind( im_buf_t *buf )
 /* Power on init.
  */
 void
-im_buf_init( im_buf_t *buf )
+vips_buf_init( VipsBuf *buf )
 {
 	buf->base = NULL;
 	buf->mx = 0;
 	buf->dynamic = FALSE;
-	im_buf_rewind( buf );
+	vips_buf_rewind( buf );
 }
 
 /* Reset to power on state ... only needed for dynamic bufs.
  */
 void
-im_buf_destroy( im_buf_t *buf )
+vips_buf_destroy( VipsBuf *buf )
 {
 	if( buf->dynamic ) {
-		if( buf->base ) {
-			im_free( buf->base );
-			buf->base = NULL;
-		}
+		IM_FREE( buf->base );
 	}
 
-	im_buf_init( buf );
+	vips_buf_init( buf );
 }
 
 /* Set to a static string.
  */
 void
-im_buf_set_static( im_buf_t *buf, char *base, int mx )
+vips_buf_set_static( VipsBuf *buf, char *base, int mx )
 {
-	assert( mx >= 4 );
+	g_assert( mx >= 4 );
 
-	im_buf_destroy( buf );
+	vips_buf_destroy( buf );
 
 	buf->base = base;
 	buf->mx = mx;
 	buf->dynamic = FALSE;
-	im_buf_rewind( buf );
+	vips_buf_rewind( buf );
 }
 
 void
-im_buf_init_static( im_buf_t *buf, char *base, int mx )
+vips_buf_init_static( VipsBuf *buf, char *base, int mx )
 {
-	im_buf_init( buf );
-	im_buf_set_static( buf, base, mx );
+	vips_buf_init( buf );
+	vips_buf_set_static( buf, base, mx );
 }
 
 /* Set to a dynamic string.
  */
 void
-im_buf_set_dynamic( im_buf_t *buf, int mx )
+vips_buf_set_dynamic( VipsBuf *buf, int mx )
 {
-	assert( mx >= 4 );
+	g_assert( mx >= 4 );
 
 	if( buf->mx == mx && buf->dynamic ) 
 		/* No change?
 		 */
-		im_buf_rewind( buf );
+		vips_buf_rewind( buf );
 	else {
-		im_buf_destroy( buf );
+		vips_buf_destroy( buf );
 
 		if( !(buf->base = IM_ARRAY( NULL, mx, char )) )
 			/* No error return, so just block writes.
@@ -133,23 +130,23 @@ im_buf_set_dynamic( im_buf_t *buf, int mx )
 		else {
 			buf->mx = mx;
 			buf->dynamic = TRUE;
-			im_buf_rewind( buf );
+			vips_buf_rewind( buf );
 		}
 	}
 }
 
 void
-im_buf_init_dynamic( im_buf_t *buf, int mx )
+vips_buf_init_dynamic( VipsBuf *buf, int mx )
 {
-	im_buf_init( buf );
-	im_buf_set_dynamic( buf, mx );
+	vips_buf_init( buf );
+	vips_buf_set_dynamic( buf, mx );
 }
 
 /* Append at most sz chars from string to buf. sz < 0 means unlimited.
- * FALSE on overflow.
+ * Error on overflow.
  */
 gboolean
-im_buf_appendns( im_buf_t *buf, const char *str, int sz )
+vips_buf_appendns( VipsBuf *buf, const char *str, int sz )
 {
 	int len;
 	int n;
@@ -191,41 +188,28 @@ im_buf_appendns( im_buf_t *buf, const char *str, int sz )
 /* Append a string to a buf. Error on overflow.
  */
 gboolean
-im_buf_appends( im_buf_t *buf, const char *str )
+vips_buf_appends( VipsBuf *buf, const char *str )
 {
-	return( im_buf_appendns( buf, str, -1 ) );
+	return( vips_buf_appendns( buf, str, -1 ) );
 }
 
 /* Append a character to a buf. Error on overflow.
  */
 gboolean
-im_buf_appendc( im_buf_t *buf, char ch )
+vips_buf_appendc( VipsBuf *buf, char ch )
 {
 	char tiny[2];
 
 	tiny[0] = ch;
 	tiny[1] = '\0';
 
-	return( im_buf_appendns( buf, tiny, 1 ) );
+	return( vips_buf_appendns( buf, tiny, 1 ) );
 }
 
-/* Append a double, non-localised. Useful for config files etc.
- */
-gboolean
-im_buf_appendg( im_buf_t *buf, double g )
-{
-	char text[G_ASCII_DTOSTR_BUF_SIZE];
-
-	g_ascii_dtostr( text, sizeof( text ), g );
-
-	return( im_buf_appends( buf, text ) );
-}
-
-
 /* Swap the rightmost occurence of old for new.
  */
 gboolean
-im_buf_change( im_buf_t *buf, const char *old, const char *new )
+vips_buf_change( VipsBuf *buf, const char *old, const char *new )
 {
 	int olen = strlen( old );
 	int nlen = strlen( new );
@@ -243,7 +227,7 @@ im_buf_change( im_buf_t *buf, const char *old, const char *new )
 	for( i = buf->i - olen; i > 0; i-- )
 		if( im_isprefix( old, buf->base + i ) )
 			break;
-	assert( i >= 0 );
+	g_assert( i >= 0 );
 
 	/* Move tail of buffer to make right-size space for new.
 	 */
@@ -258,75 +242,126 @@ im_buf_change( im_buf_t *buf, const char *old, const char *new )
 	return( TRUE );
 }
 
-/* Remove the last character.
+/* Remove the last character, if it's ch.
  */
 gboolean
-im_buf_removec( im_buf_t *buf, char ch )
+vips_buf_removec( VipsBuf *buf, char ch )
 {
 	if( buf->full )
 		return( FALSE );
-
 	if( buf->i <= 0 ) 
 		return( FALSE );
-	buf->i -= 1;
-	assert( buf->base[buf->i] == ch );
+	if( buf->base[buf->i - 1] == ch )
+		buf->i -= 1;
 
 	return( TRUE );
 }
 
-/* Append to a buf, args as printf. FALSE on overflow.
+/* Append to a buf, args as printf. Error on overflow.
  */
 gboolean
-im_buf_appendf( im_buf_t *buf, const char *fmt, ... )
+vips_buf_appendf( VipsBuf *buf, const char *fmt, ... )
 {
-	va_list ap;
 	char str[MAX_STRSIZE];
+	va_list ap;
 
         va_start( ap, fmt );
         (void) im_vsnprintf( str, MAX_STRSIZE, fmt, ap );
         va_end( ap );
 
-	return( im_buf_appends( buf, str ) );
+	return( vips_buf_appends( buf, str ) );
 }
 
 /* Append to a buf, args as vprintf. Error on overflow.
  */
 gboolean
-im_buf_vappendf( im_buf_t *buf, const char *fmt, va_list ap )
+vips_buf_vappendf( VipsBuf *buf, const char *fmt, va_list ap )
 {
 	char str[MAX_STRSIZE];
 
         (void) im_vsnprintf( str, MAX_STRSIZE, fmt, ap );
 
-	return( im_buf_appends( buf, str ) );
+	return( vips_buf_appends( buf, str ) );
+}
+
+/* Append a double, non-localised. Useful for config files etc.
+ */
+gboolean
+vips_buf_appendg( VipsBuf *buf, double g )
+{
+	char text[G_ASCII_DTOSTR_BUF_SIZE];
+
+	g_ascii_dtostr( text, sizeof( text ), g );
+
+	return( vips_buf_appends( buf, text ) );
+}
+
+/* Append a number ... if the number is -ve, add brackets. Needed for
+ * building function arguments.
+ */
+gboolean
+vips_buf_appendd( VipsBuf *buf, int d )
+{
+	if( d < 0 )
+		return( vips_buf_appendf( buf, " (%d)", d ) );
+	else
+		return( vips_buf_appendf( buf, " %d", d ) );
+}
+
+void
+vips_buf_appendgv( VipsBuf *buf, GValue *value )
+{
+	char *str_value;
+
+	str_value = g_strdup_value_contents( value );
+	vips_buf_appends( buf, str_value );
+	g_free( str_value );
 }
 
 /* Read all text from buffer.
  */
 const char *
-im_buf_all( im_buf_t *buf )
+vips_buf_all( VipsBuf *buf )
 {
 	buf->base[buf->i] = '\0';
 
 	return( buf->base );
 }
 
+/* Trim to just the first line (excluding "\n").
+ */
+const char *
+vips_buf_firstline( VipsBuf *buf )
+{
+	char *p;
+
+	if( (p = strchr( vips_buf_all( buf ), '\n' )) )
+		*p = '\0';
+
+	return( vips_buf_all( buf ) );
+}
+
+/* Test for buffer empty.
+ */
 gboolean
-im_buf_isempty( im_buf_t *buf )
+vips_buf_is_empty( VipsBuf *buf )
 {
 	return( buf->i == 0 );
 }
 
+/* Test for buffer full.
+ */
 gboolean
-im_buf_isfull( im_buf_t *buf )
+vips_buf_is_full( VipsBuf *buf )
 {
 	return( buf->full );
 }
 
-/* Buffer length ... still need to do im_buf_all().
+/* VipsBuffer length ... still need to do vips_buf_all().
  */
 int
-im_buf_len( im_buf_t *buf )
+vips_buf_len( VipsBuf *buf )
 {
 	return( buf->i );
 }
+
diff --git a/libsrc/iofuncs/error.c b/libsrc/iofuncs/error.c
index 4fd52eb4..3a670fd0 100644
--- a/libsrc/iofuncs/error.c
+++ b/libsrc/iofuncs/error.c
@@ -70,8 +70,8 @@
  */
 #define IM_MAX_ERROR (10240)
 static char im_error_text[IM_MAX_ERROR] = "";
-static im_buf_t im_error_buf = 
-	IM_BUF_STATIC( im_error_text, IM_MAX_ERROR );
+static VipsBuf im_error_buf = 
+	VIPS_BUF_STATIC( im_error_text, IM_MAX_ERROR );
 
 #define IM_DIAGNOSTICS "IM_DIAGNOSTICS"
 #define IM_WARNING "IM_WARNING"
@@ -82,7 +82,7 @@ im_error_buffer( void )
 	const char *msg;
 
 	g_mutex_lock( im__global_lock );
-	msg = im_buf_all( &im_error_buf );
+	msg = vips_buf_all( &im_error_buf );
 	g_mutex_unlock( im__global_lock );
 
 	return( msg );
@@ -92,9 +92,9 @@ void
 im_verror( const char *domain, const char *fmt, va_list ap )
 {
 	g_mutex_lock( im__global_lock );
-	im_buf_appendf( &im_error_buf, "%s: ", domain );
-	im_buf_vappendf( &im_error_buf, fmt, ap );
-	im_buf_appends( &im_error_buf, "\n" );
+	vips_buf_appendf( &im_error_buf, "%s: ", domain );
+	vips_buf_vappendf( &im_error_buf, fmt, ap );
+	vips_buf_appends( &im_error_buf, "\n" );
 	g_mutex_unlock( im__global_lock );
 }
 
@@ -154,7 +154,7 @@ void
 im_error_clear( void )
 {
 	g_mutex_lock( im__global_lock );
-	im_buf_rewind( &im_error_buf );
+	vips_buf_rewind( &im_error_buf );
 	g_mutex_unlock( im__global_lock );
 }
 
diff --git a/libsrc/iofuncs/im_updatehist.c b/libsrc/iofuncs/im_updatehist.c
index db91cef7..20244c68 100644
--- a/libsrc/iofuncs/im_updatehist.c
+++ b/libsrc/iofuncs/im_updatehist.c
@@ -63,17 +63,17 @@ im_updatehist( IMAGE *out, const char *name, int argc, char *argv[] )
 {	
 	int i;
 	char txt[IM_MAX_LINE];
-	im_buf_t buf;
+	VipsBuf buf;
 
-	im_buf_init_static( &buf, txt, IM_MAX_LINE );
-	im_buf_appends( &buf, name );
+	vips_buf_init_static( &buf, txt, IM_MAX_LINE );
+	vips_buf_appends( &buf, name );
 
 	for( i = 0; i < argc; i++ ) {
-		im_buf_appends( &buf, " " );
-		im_buf_appends( &buf, argv[i] );
+		vips_buf_appends( &buf, " " );
+		vips_buf_appends( &buf, argv[i] );
 	}
 
-	if( im_histlin( out, "%s", im_buf_all( &buf ) ) ) 
+	if( im_histlin( out, "%s", vips_buf_all( &buf ) ) ) 
 		return( -1 );
 
 	return( 0 );
diff --git a/libsrc/iofuncs/object.c b/libsrc/iofuncs/object.c
index 707fc42d..f40a9cab 100644
--- a/libsrc/iofuncs/object.c
+++ b/libsrc/iofuncs/object.c
@@ -92,25 +92,25 @@ vips_object_build( VipsObject *object )
 void
 vips_object_print_class( VipsObjectClass *class )
 {
-	im_buf_t buf;
+	VipsBuf buf;
 	char str[1000];
 
-	im_buf_init_static( &buf, str, 1000 );
+	vips_buf_init_static( &buf, str, 1000 );
 	class->print_class( class, &buf );
-	printf( "%s\n", im_buf_all( &buf ) );
+	printf( "%s\n", vips_buf_all( &buf ) );
 }
 
 void
 vips_object_print( VipsObject *object )
 {
 	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
-	im_buf_t buf;
+	VipsBuf buf;
 	char str[1000];
 
 	vips_object_print_class( class );
-	im_buf_init_static( &buf, str, 1000 );
+	vips_buf_init_static( &buf, str, 1000 );
 	class->print( object, &buf );
-	printf( "\n%s (%p)\n", im_buf_all( &buf ), object );
+	printf( "\n%s (%p)\n", vips_buf_all( &buf ), object );
 }
 
 /* Extra stuff we track for properties to do our argument handling.
@@ -459,7 +459,7 @@ vips_object_set_property( GObject *gobject,
 
 	str_value = g_strdup_value_contents( value );
 	printf( "vips_object_set_property: %s.%s = %s\n", 
-		object->name, pspec->name, str_value );
+		object->name, g_param_spec_get_name( pspec ), str_value );
 	g_free( str_value );
 }
 #endif /*DEBUG*/
@@ -472,8 +472,10 @@ vips_object_set_property( GObject *gobject,
 	 */
 	if( argument_class->flags & VIPS_ARGUMENT_CONSTRUCT && 
 		object->constructed ) {
-		g_warning( "%s: can't assign '%s' after construct", G_STRLOC,
-			((VipsArgument *) argument_class)->pspec->name);
+		g_warning( "%s: %s can't assign '%s' after construct", 
+			G_STRLOC,
+			G_OBJECT_TYPE_NAME( gobject ),
+			g_param_spec_get_name( pspec ) );
 		return;
 	}
 
@@ -481,8 +483,10 @@ vips_object_set_property( GObject *gobject,
 	 */
 	if( argument_class->flags & VIPS_ARGUMENT_SET_ONCE &&
 		argument_instance->assigned ) {
-		g_warning( "%s: can only assign '%s' once", G_STRLOC,
-			((VipsArgument *)argument_class)->pspec->name );
+		g_warning( "%s: %s can only assign '%s' once", 
+			G_STRLOC,
+			G_OBJECT_TYPE_NAME( gobject ),
+			g_param_spec_get_name( pspec ) );
 		return;
 	}
 
@@ -548,8 +552,10 @@ vips_object_set_property( GObject *gobject,
 		*member = g_value_dup_boxed( value );
 	}
 	else {
-		g_warning( "%s: '%s' has unimplemented type", G_STRLOC,
-			((VipsArgument *) argument_class)->pspec->name );
+		g_warning( "%s: %s unimplemented property type %s", 
+			G_STRLOC, 
+			G_OBJECT_TYPE_NAME( gobject ),
+			g_type_name( G_PARAM_SPEC_VALUE_TYPE( pspec ) ) );
 	}
 
 	/* Note that it's now been set. 
@@ -612,6 +618,12 @@ vips_object_get_property( GObject *gobject,
 
 		g_value_set_pointer( value, *member );
 	}
+	else if( G_IS_PARAM_SPEC_DOUBLE( pspec ) ) {
+		double *member = &G_STRUCT_MEMBER( double, object, 
+			argument_class->offset );
+
+		g_value_set_double( value, *member );
+	}
 	else if( G_IS_PARAM_SPEC_BOXED( pspec ) ) {
 		gpointer *member = &G_STRUCT_MEMBER( gpointer, object, 
 			argument_class->offset );
@@ -622,7 +634,10 @@ vips_object_get_property( GObject *gobject,
 		g_value_set_boxed( value, *member );
 	}
 	else {
-		g_warning( "%s: unimplemented property type", G_STRLOC );
+		g_warning( "%s: %s unimplemented property type %s", 
+			G_STRLOC, 
+			G_OBJECT_TYPE_NAME( gobject ),
+			g_type_name( G_PARAM_SPEC_VALUE_TYPE( pspec ) ) );
 	}
 }
 
@@ -639,7 +654,7 @@ vips_object_check_required( VipsObject *object, GParamSpec *pspec,
 		!argument_instance->assigned ) {
 		im_error( "check_required", 
 			_( "required construct param %s to %s %s not set" ),
-			pspec->name,
+			g_param_spec_get_name( pspec ),
 			G_OBJECT_TYPE_NAME( object ),
 			object->name );
 		*result = -1;
@@ -679,20 +694,20 @@ vips_object_real_changed( VipsObject *object )
 }
 
 static void
-vips_object_real_print_class( VipsObjectClass *class, im_buf_t *buf )
+vips_object_real_print_class( VipsObjectClass *class, VipsBuf *buf )
 {
-	im_buf_appendf( buf, "%s", G_OBJECT_CLASS_NAME( class ) );
+	vips_buf_appendf( buf, "%s", G_OBJECT_CLASS_NAME( class ) );
 	if( class->nickname )
-		im_buf_appendf( buf, " (%s)", class->nickname );
+		vips_buf_appendf( buf, " (%s)", class->nickname );
 	if( class->description )
-		im_buf_appendf( buf, ", %s", class->description );
+		vips_buf_appendf( buf, ", %s", class->description );
 }
 
 static void
-vips_object_real_print( VipsObject *object, im_buf_t *buf )
+vips_object_real_print( VipsObject *object, VipsBuf *buf )
 {
 	if( object->name )
-		im_buf_appendf( buf, "\"%s\"", object->name );
+		vips_buf_appendf( buf, "\"%s\"", object->name );
 }
 
 static void
@@ -910,7 +925,7 @@ vips_object_new_from_string( const char *basename, const char *p )
 		if( token == VIPS_TOKEN_LEFT &&
 			vips_object_set_args( object, p ) ) {
 			im_error( "object_new", "%s",
-				_( "bad object arguents" ) );
+				_( "bad object arguments" ) );
 			g_object_unref( object );
 			return( NULL );
 		}
@@ -924,3 +939,94 @@ vips_object_new_from_string( const char *basename, const char *p )
 	return( object );
 }
 
+static void
+vips_object_print_arg( VipsObject *object, GParamSpec *pspec, VipsBuf *buf )
+{
+	GType type = G_PARAM_SPEC_VALUE_TYPE( pspec );
+	const char *name = g_param_spec_get_name( pspec );
+	GValue value = { 0 };
+	char *str_value;
+
+	g_value_init( &value, type );
+	g_object_get_property( G_OBJECT( object ), name, &value );
+	str_value = g_strdup_value_contents( &value );
+	vips_buf_appends( buf, str_value );
+	g_free( str_value );
+	g_value_unset( &value );
+
+}
+
+static void *
+vips_object_to_string_required( VipsObject *object,
+	GParamSpec *pspec,
+	VipsArgumentClass *argument_class, 
+	VipsArgumentInstance *argument_instance,
+	void *a, void *b )
+{
+	VipsBuf *buf = (VipsBuf *) a;
+	gboolean *first = (gboolean *) b;
+
+	if( (argument_class->flags & VIPS_ARGUMENT_REQUIRED) ) {
+		if( *first ) {
+			vips_buf_appends( buf, "(" );
+			*first = FALSE;
+		}
+		else {
+			vips_buf_appends( buf, "," );
+		}
+
+		vips_object_print_arg( object, pspec, buf ); 
+	}
+
+	return( NULL );
+}
+
+static void *
+vips_object_to_string_optional( VipsObject *object,
+	GParamSpec *pspec,
+	VipsArgumentClass *argument_class, 
+	VipsArgumentInstance *argument_instance,
+	void *a, void *b )
+{
+	VipsBuf *buf = (VipsBuf *) a;
+	gboolean *first = (gboolean *) b;
+
+	if( !(argument_class->flags & VIPS_ARGUMENT_REQUIRED) &&
+		argument_instance->assigned ) {
+		if( *first ) {
+			vips_buf_appends( buf, "(" );
+			*first = FALSE;
+		}
+		else {
+			vips_buf_appends( buf, "," );
+		}
+
+		vips_buf_appends( buf, g_param_spec_get_name( pspec ) );
+		vips_buf_appends( buf, "=" );
+		vips_object_print_arg( object, pspec, buf ); 
+	}
+
+	return( NULL );
+}
+
+/* The inverse of vips_object_new_from_string(): turn an object into eg.
+ * "VipsInterpolateYafrsmooth(sharpening=12)".
+ */
+void
+vips_object_to_string( VipsObject *object, VipsBuf *buf )
+{
+	VipsObjectClass *object_class = VIPS_OBJECT_GET_CLASS( object );
+	gboolean first;
+
+	/* Nicknames are not guaranteed to be unique, so use the full type
+	 * name.
+	 */
+	vips_buf_appends( buf, G_OBJECT_TYPE_NAME( object ) );
+	first = TRUE;
+	(void) vips_argument_map( object, 
+		vips_object_to_string_required, buf, &first );
+	(void) vips_argument_map( object, 
+		vips_object_to_string_optional, buf, &first );
+	if( !first ) 
+		vips_buf_appends( buf, ")" );
+}
diff --git a/libsrc/mosaicing/mosaic1.c b/libsrc/mosaicing/mosaic1.c
index a76926f9..0941350c 100644
--- a/libsrc/mosaicing/mosaic1.c
+++ b/libsrc/mosaicing/mosaic1.c
@@ -106,7 +106,7 @@ im__lrmerge1( IMAGE *ref, IMAGE *sec, IMAGE *out,
 {
 	Transformation trn;
 	IMAGE *t1 = im_open_local( out, "im_lrmosaic1:1", "p" );
-	im_buf_t buf;
+	VipsBuf buf;
 	char text[1024];
 
 	/* Scale, rotate and displace sec.
@@ -123,18 +123,18 @@ im__lrmerge1( IMAGE *ref, IMAGE *sec, IMAGE *out,
 	/* Note parameters in history file ... for global balance to pick up
 	 * later.
 	 */
-	im_buf_init_static( &buf, text, 1024 );
-	im_buf_appendf( &buf, "#LRROTSCALE <%s> <%s> <%s> <",
+	vips_buf_init_static( &buf, text, 1024 );
+	vips_buf_appendf( &buf, "#LRROTSCALE <%s> <%s> <%s> <",
 		ref->filename, sec->filename, out->filename ); 
-	im_buf_appendg( &buf, a );
-	im_buf_appendf( &buf, "> <" );
-	im_buf_appendg( &buf, b );
-	im_buf_appendf( &buf, "> <" );
-	im_buf_appendg( &buf, dx );
-	im_buf_appendf( &buf, "> <" );
-	im_buf_appendg( &buf, dy );
-	im_buf_appendf( &buf, "> <%d>", mwidth );
-	if( im_histlin( out, "%s", im_buf_all( &buf ) ) )
+	vips_buf_appendg( &buf, a );
+	vips_buf_appendf( &buf, "> <" );
+	vips_buf_appendg( &buf, b );
+	vips_buf_appendf( &buf, "> <" );
+	vips_buf_appendg( &buf, dx );
+	vips_buf_appendf( &buf, "> <" );
+	vips_buf_appendg( &buf, dy );
+	vips_buf_appendf( &buf, "> <%d>", mwidth );
+	if( im_histlin( out, "%s", vips_buf_all( &buf ) ) )
 		return( -1 );
 
 	return( 0 );
@@ -148,7 +148,7 @@ im__tbmerge1( IMAGE *ref, IMAGE *sec, IMAGE *out,
 {
 	Transformation trn;
 	IMAGE *t1 = im_open_local( out, "im_lrmosaic1:2", "p" );
-	im_buf_t buf;
+	VipsBuf buf;
 	char text[1024];
 
 	/* Scale, rotate and displace sec.
@@ -165,18 +165,18 @@ im__tbmerge1( IMAGE *ref, IMAGE *sec, IMAGE *out,
 	/* Note parameters in history file ... for global balance to pick up
 	 * later.
 	 */
-	im_buf_init_static( &buf, text, 1024 );
-	im_buf_appendf( &buf, "#TBROTSCALE <%s> <%s> <%s> <",
+	vips_buf_init_static( &buf, text, 1024 );
+	vips_buf_appendf( &buf, "#TBROTSCALE <%s> <%s> <%s> <",
 		ref->filename, sec->filename, out->filename ); 
-	im_buf_appendg( &buf, a );
-	im_buf_appendf( &buf, "> <" );
-	im_buf_appendg( &buf, b );
-	im_buf_appendf( &buf, "> <" );
-	im_buf_appendg( &buf, dx );
-	im_buf_appendf( &buf, "> <" );
-	im_buf_appendg( &buf, dy );
-	im_buf_appendf( &buf, "> <%d>", mwidth );
-	if( im_histlin( out, "%s", im_buf_all( &buf ) ) )
+	vips_buf_appendg( &buf, a );
+	vips_buf_appendf( &buf, "> <" );
+	vips_buf_appendg( &buf, b );
+	vips_buf_appendf( &buf, "> <" );
+	vips_buf_appendg( &buf, dx );
+	vips_buf_appendf( &buf, "> <" );
+	vips_buf_appendg( &buf, dy );
+	vips_buf_appendf( &buf, "> <%d>", mwidth );
+	if( im_histlin( out, "%s", vips_buf_all( &buf ) ) )
 		return( -1 );
 
 	return( 0 );