Index: openacs-4/packages/xotcl-core/xotcl-core.info
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/xotcl-core.info,v
diff -u -r1.11 -r1.12
--- openacs-4/packages/xotcl-core/xotcl-core.info	22 Feb 2006 12:33:52 -0000	1.11
+++ openacs-4/packages/xotcl-core/xotcl-core.info	10 Apr 2006 10:22:12 -0000	1.12
@@ -28,6 +28,7 @@
         <provides url="xotcl-core" version="0.36"/>
 
         <callbacks>
+            <callback type="before-install"  proc="::xotcl::before_install_callback"/>
         </callbacks>
         <parameters>
         <!-- No version parameters -->
Index: openacs-4/packages/xotcl-core/tcl/install-check-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/tcl/install-check-procs.tcl,v
diff -u
--- /dev/null	1 Jan 1970 00:00:00 -0000
+++ openacs-4/packages/xotcl-core/tcl/install-check-procs.tcl	10 Apr 2006 10:22:12 -0000	1.1
@@ -0,0 +1,14 @@
+ad_proc ::xotcl::before_install_callback {} {
+  
+  Callback for checking whether xotcl is installed for OpenACS
+  
+  @author Gustaf Neumann (neumann@wu-wien.ac.at)
+} {
+  ns_log notice "-- before-install callback"
+  if {[info command ::xotcl::Class] eq ""} {
+    error " XOTcl does not appear to be installed on your system!\n\
+     Please follow the install instructions on http://www.openacs.org/xowiki/pages/en/xotcl-core"
+  } else {
+    ns_log notice "XOTcl [package require XOTcl] appears to be installed on your system."
+  }
+}