Index: trunk/src_plugins/order/constraint.c
===================================================================
--- trunk/src_plugins/order/constraint.c	(revision 36871)
+++ trunk/src_plugins/order/constraint.c	(revision 36872)
@@ -340,7 +340,12 @@
 			break;
 
 		case PCB_ORDC_VAR:
-			printf("var '$%s'\n", node->val.s);
+			dst->type = PCB_ORDC_VERR; /* assume error and let var_cb override it */
+
+			if (ctx->var_cb == NULL)
+				break; /* everything evaluates to error */
+
+			ctx->var_cb(ctx, dst, node->val.s); /* no need to convert; grammar ensures static string */
 			break;
 
 		case PCB_ORDC_INT:
Index: trunk/src_plugins/order/constraint.h
===================================================================
--- trunk/src_plugins/order/constraint.h	(revision 36871)
+++ trunk/src_plugins/order/constraint.h	(revision 36872)
@@ -68,6 +68,7 @@
 
 	/*** application provided callbacks ***/
 	void (*error_cb)(pcb_ordc_ctx_t *ctx, const char *varname, const char *msg);
+	void (*var_cb)(pcb_ordc_ctx_t *ctx, pcb_ordc_val_t *dst, const char *varname);
 };
 
 int pcb_ordc_parse_str(pcb_ordc_ctx_t *ctx, const char *script);
@@ -77,7 +78,7 @@
 
 void pcb_ordc_free_tree(pcb_ordc_ctx_t *ctx, pcb_ordc_node_t *node);
 
-pcb_ordc_exec(pcb_ordc_ctx_t *ctx);
+int pcb_ordc_exec(pcb_ordc_ctx_t *ctx);
 
 /*** For debug ***/
 void pcb_ordc_print_tree(FILE *f, pcb_ordc_ctx_t *ctx, pcb_ordc_node_t *node, int indlev);