Index: order_const/tester.c
===================================================================
--- order_const/tester.c	(revision 36880)
+++ order_const/tester.c	(revision 36881)
@@ -4,13 +4,40 @@
 int verbose = 0;
 extern int pcb_ordc_parse_verbose;
 
+static void error_cb(pcb_ordc_ctx_t *ctx, const char *varname, const char *msg, void **ucache)
+{
+	printf("Constraint error: %s: %s\n", varname, msg);
+}
+
+void var_cb(pcb_ordc_ctx_t *ctx, pcb_ordc_val_t *dst, const char *varname, void **ucache)
+{
+	if (strcmp(varname, "one") == 0) {
+		dst->type = PCB_ORDC_VLNG;
+		dst->val.l = 1;
+		return;
+	}
+	if (strcmp(varname, "pi") == 0) {
+		dst->type = PCB_ORDC_VDBL;
+		dst->val.d = 3.141592654;
+		return;
+	}
+	if (strcmp(varname, "hello") == 0) {
+		dst->type = PCB_ORDC_VCSTR;
+		dst->val.s = "10 hello world";
+		return;
+	}
+}
+
 int main(int argc, char *argv[])
 {
-	pcb_ordc_ctx_t ctx;
+	pcb_ordc_ctx_t ctx = {0};
 	char script[8192], *fn = argv[1];
 	FILE *f;
 	int r;
 
+	ctx.error_cb = error_cb;
+	ctx.var_cb = var_cb;
+
 	if (strcmp(argv[1], "-v") == 0) {
 		verbose = pcb_ordc_parse_verbose = 1;
 		fn = argv[2];
@@ -35,6 +62,19 @@
 		return 1;
 	}
 
+	printf("------ AST ------\n");
+	if (ctx.root != NULL)
+		pcb_ordc_print_tree(stdout, &ctx, ctx.root, 0);
+	else
+		printf("<no root>\n");
 
+
+	printf("------ exec ------\n");
+	r = pcb_ordc_exec(&ctx);
+	if (r < 0)
+		printf("Runtime error.\n");
+
+	pcb_ordc_uninit(&ctx);
+
 	return 0;
 }