Index: openacs-4/packages/xotcl-core/tcl/01-debug-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/tcl/01-debug-procs.tcl,v
diff -u -r1.84 -r1.85
--- openacs-4/packages/xotcl-core/tcl/01-debug-procs.tcl	22 Dec 2017 13:51:55 -0000	1.84
+++ openacs-4/packages/xotcl-core/tcl/01-debug-procs.tcl	24 Dec 2017 12:28:07 -0000	1.85
@@ -346,7 +346,9 @@
     if {$m<$max} {set max $m}
     ::xotcl::Object  log "### Call Stack (level: command)"
     for {set i 0} {$i < $max} {incr i} {
-      if {[catch {set s [uplevel $i self]} msg]} {
+      try {
+        set s [uplevel $i self]
+      } on error {errorMsg} {
         set s ""
       }
       ::xotcl::Object  log "### [format %5d -$i]:\t$s [info level [expr {-$i}]]"
@@ -507,10 +509,12 @@
         continue
       }
       #ns_log notice "*** cleanup $cmd"
-      if {[catch {eval $cmd} errorMsg]} {
+      try {
+        {*}$cmd
+      } on error {errorMsg} {
         set obj [lindex $cmd 0]
         ns_log error "Error during ::xo::cleanup: $errorMsg $::errorInfo"
-        catch {
+        try {
           ns_log notice "... analyze: cmd = $cmd"
           ns_log notice "... analyze: $obj is_object? [::xotcl::Object isobject $obj]"
           ns_log notice "... analyze: class [$obj info class]"
@@ -534,7 +538,9 @@
       }
     }
     #ns_log notice "*** at_end $at_end"
-    if {[catch {eval $at_end} errorMsg]} {
+    try {
+      {*}$at_end
+    } on error {errorMsg} {
       ns_log notice "Error during ::xo::cleanup: $errorMsg $::errorInfo"
     }
     array unset ::xo::cleanup
@@ -811,7 +817,9 @@
     if {[nsv_exists broadcast $tid]} {
       foreach cmd [nsv_get broadcast $tid] {
         ns_log notice "broadcast received {$cmd}"
-        if {[catch $cmd errorMsg]} {
+        try {
+          {*}$cmd
+        } on error {errorMsg} {
           ns_log notice "broadcast receive error: $errorMsg for cmd $cmd"
         }
       }
Index: openacs-4/packages/xotcl-core/tcl/05-db-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/tcl/05-db-procs.tcl,v
diff -u -r1.112 -r1.113
--- openacs-4/packages/xotcl-core/tcl/05-db-procs.tcl	22 Dec 2017 13:51:55 -0000	1.112
+++ openacs-4/packages/xotcl-core/tcl/05-db-procs.tcl	24 Dec 2017 12:28:07 -0000	1.113
@@ -367,10 +367,12 @@
     if {$args ne ""} {
       lassign $args op on_error_code
       set result ""
-      if {$op ne "on_error"} {error "only 'on_error' as argument after script allowed"}
-      if {[catch {
+      if {$op ne "on_error"} {
+        error "only 'on_error' as argument after script allowed"
+      }
+      try {
         set result [:uplevel [list ::dbi_eval -transaction committed $script]]
-      }]} {
+      } on error {$errorMsg} {
         :uplevel $on_error_code
       }
       return $result
@@ -665,11 +667,12 @@
     # we can obtain a session_id from the the db driver. If we can't,
     # we fall back to a per request-cache (via toplevel variable).
     #
-    catch {set session_id [ns_db session_id $handle]}
-    if {[info exists session_id]} {
+    try {
+      set session_id [ns_db session_id $handle]
+    } on ok {r} {
       #ns_log notice "=== $handle $session_id"
       set varName ::xo::prepared($session_id,$key)
-    } else {
+    } on error {errorMsg} {
       set session_id "-"
       set varName __prepared($key)    
     }
@@ -735,7 +738,9 @@
   # Unfortunately, ns_cache has no command to check, whether
   # a cache exists, so we use the little catch below to check.
   #
-  if {[catch {ns_cache flush xotcl_object_cache NOTHING}]} {
+  try {
+    ns_cache flush xotcl_object_cache NOTHING
+  } on error {errorMsg} {
     ns_log notice "xotcl-core: creating xotcl-object caches"
 
     if {[info commands ns_cache_create] ne ""} {
@@ -1208,7 +1213,9 @@
       }
       append slots $cmd \n
     }
-    if {[catch {$classname slots $slots} errorMsg]} {
+    ad_try {
+      $classname slots $slots
+    } on error {errorMsg} {
       error "Error during slots: $errorMsg"
     }
 
@@ -2211,8 +2218,10 @@
                   -creation_ip $creation_ip \
                   ""]
       #[self class] set during_fetch 1
-      if {[catch {:create ::$id {*}$args} errorMsg]} {
-        ad_log error $errorMsg
+      ad_try {
+        :create ::$id {*}$args
+      } on error {errorMsg} {
+        ad_log error "create fails: $errorMsg"
       }
       #[self class] unset during_fetch
       :initialize_acs_object ::$id $id
@@ -2258,7 +2267,7 @@
     Otherwise, objects are created with the XOTcl "new" method to avoid object name clashes.
 
     @param destroy_on_cleanup If this flag is true, the objects (and ordered composite)
-      will be automatically destroyed on cleaup (typically                                                                                      after the request was processed).
+    will be automatically destroyed on cleaup (typically after the request was processed).
 
     @param initialize can be used to avoid full initialization, when
     a large series of of objects is loaded. Per default, these objects
@@ -2317,7 +2326,9 @@
             ns_log warning "[namespace tail [$o info class]] $o has no package_id and no object_package_id"
           }
         }
-        if {[catch {$o initialize_loaded_object} errorMsg]} {
+        ad_try {
+          $o initialize_loaded_object
+        } on error {errorMsg} {
           ns_log error "$o initialize_loaded_object => [$o info vars] -> $errorMsg"
         }
       }
Index: openacs-4/packages/xotcl-core/tcl/20-Ordered-Composite-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/tcl/20-Ordered-Composite-procs.tcl,v
diff -u -r1.25 -r1.26
--- openacs-4/packages/xotcl-core/tcl/20-Ordered-Composite-procs.tcl	13 Dec 2017 20:42:31 -0000	1.25
+++ openacs-4/packages/xotcl-core/tcl/20-Ordered-Composite-procs.tcl	24 Dec 2017 12:28:07 -0000	1.26
@@ -92,18 +92,24 @@
     [self class]::ChildManager instvar composite
     # push the active composite
     lappend composite [self]
-    # check, if we have Tcl's apply available
-    if {$::tcl_version >= 8.5 && [info procs ::apply] eq ""} {
-      set errorOccurred [catch {::apply [list {} $cmds [self]]} errorMsg]
+    set errorOccurred 0
+    # check, if we have Tcl's apply available    
+    if {[info procs ::apply] eq ""} {
+      set applyCmd [list ::apply [list {} $cmds [self]]]
     } else {
-      set errorOccurred [catch {namespace eval [self] $cmds} errorMsg]
+      set applyCmd [list namespace eval [self] $cmds]
     }
+    try {
+      {*}$applyCmd
+    } on error {errorMsg} {
+      set errorOccurred 1
+    } finally {
+      # pop the last active composite
+      set composite [lrange $composite 0 end-1]
 
-    # pop the last active composite
-    set composite [lrange $composite 0 end-1]
-
-    if {$insert} {
-      Object instmixin delete [self class]::ChildManager
+      if {$insert} {
+        Object instmixin delete [self class]::ChildManager
+      }
     }
     if {$errorOccurred} {error $errorMsg}
   }
Index: openacs-4/packages/xotcl-core/tcl/30-widget-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/tcl/30-widget-procs.tcl,v
diff -u -r1.60 -r1.61
--- openacs-4/packages/xotcl-core/tcl/30-widget-procs.tcl	22 Dec 2017 13:51:55 -0000	1.60
+++ openacs-4/packages/xotcl-core/tcl/30-widget-procs.tcl	24 Dec 2017 12:28:07 -0000	1.61
@@ -365,15 +365,19 @@
   #
   proc get_user_name {uid} {
     if {$uid ne "" && $uid != 0} {
-      if {[catch {acs_user::get -user_id $uid -array user}]} {
+      ad_try {
+        acs_user::get -user_id $uid -array user
+      } on error {errorMsg} {
         # we saw some strange cases, where after a regression,
         # a user_id was present, which was already deleted...
-        return [_ xotcl-core.nobody]
+        set result [_ xotcl-core.nobody]
+      } on ok {r} {
+        set result "$user(first_names) $user(last_name)"
       }
-      return "$user(first_names) $user(last_name)"
     } else {
-      return [_ xotcl-core.nobody]
+      set result [_ xotcl-core.nobody]
     }
+    return $result
   }
 
   #
Index: openacs-4/packages/xotcl-core/tcl/chat-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/tcl/Attic/chat-procs.tcl,v
diff -u -r1.29 -r1.30
--- openacs-4/packages/xotcl-core/tcl/chat-procs.tcl	13 Dec 2017 20:42:31 -0000	1.29
+++ openacs-4/packages/xotcl-core/tcl/chat-procs.tcl	24 Dec 2017 12:28:07 -0000	1.30
@@ -152,7 +152,7 @@
       # was 1200
       if {$ago > 300} {
         :logout -user_id $user -msg "auto logout"
-        catch {::bgdelivery do ::Subscriber sweep chat-[:chat_id]}
+        try {::bgdelivery do ::Subscriber sweep chat-[:chat_id]}
       }
     }
     :log "-- ending"
@@ -168,13 +168,13 @@
     
     # This values could already not be here. Just ignore when we don't
     # find them
-    catch {
+    try {
       ::xo::clusterwide nsv_unset -nocomplain ${:array}-login $user_id
     }
-    catch {
+    try {
       ::xo::clusterwide nsv_unset -nocomplain ${:array}-color $user_id
     }
-    catch {
+    try {
       ::xo::clusterwide nsv_unset -nocomplain ${:array}-last-activity $user_id
     }
   }
Index: openacs-4/packages/xotcl-core/tcl/cluster-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/tcl/cluster-procs.tcl,v
diff -u -r1.11 -r1.12
--- openacs-4/packages/xotcl-core/tcl/cluster-procs.tcl	13 Dec 2017 20:42:31 -0000	1.11
+++ openacs-4/packages/xotcl-core/tcl/cluster-procs.tcl	24 Dec 2017 12:28:07 -0000	1.12
@@ -74,10 +74,12 @@
     set addr [lindex [ns_set iget [ns_conn headers] x-forwarded-for] end]
     if {$addr eq ""} {set addr [ns_conn peeraddr]}
     #ns_log notice "--cluster got cmd='$cmd' from $addr"
-    if {[catch {set result [::xo::Cluster execute [ns_conn peeraddr] $cmd]} errorMsg]} {
+    ad_try {
+      set result [::xo::Cluster execute [ns_conn peeraddr] $cmd]
+    } on error {errorMsg} {
       ns_log notice "--cluster error: $errorMsg"
       ns_return 417 text/plain $errorMsg
-    } else {
+    } on ok {r} {
       #ns_log notice "--cluster success $result"
       ns_return 200 text/plain $result
     }
Index: openacs-4/packages/xotcl-core/tcl/context-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/tcl/context-procs.tcl,v
diff -u -r1.69 -r1.70
--- openacs-4/packages/xotcl-core/tcl/context-procs.tcl	13 Dec 2017 20:42:31 -0000	1.69
+++ openacs-4/packages/xotcl-core/tcl/context-procs.tcl	24 Dec 2017 12:28:07 -0000	1.70
@@ -248,8 +248,10 @@
     if {[ns_conn isconnected]} {
       # This can be called, before ad_conn is initialized. 
       # Since it is not possible to pass the user_id and ad_conn barfs
-      # when it tries to detect it, we use the catch and reset it later
-      if {[catch {set locale [lang::conn::locale -package_id $package_id]}]} {
+      # when it tries to detect it, we try to get it and reset it later
+      ad_try {
+        set locale [lang::conn::locale -package_id $package_id]
+      } on error {errorMsg} {
         set locale en_US
       }
     } else {
@@ -273,9 +275,7 @@
           -actual_query $actual_query \
           -locale $locale \
           [list -parameter_declaration $parameter]
-      #if {$package_id ne ""} {
-      #  ::xo::cc package_id $package_id 
-      #}
+
       ::xo::cc package_id $package_id 
       ::xo::cc set_user_id $user_id
       ::xo::cc process_query_parameter
@@ -301,8 +301,10 @@
     if {$user_id == -1} {  ;# not specified
       if {[info exists ::ad_conn(user_id)]} {
         set :user_id [ad_conn user_id]
-        if {[catch {set :untrusted_user_id [ad_conn untrusted_user_id]}]} {
-          set :untrusted_user_id [:user_id]
+        ad_try {
+          set :untrusted_user_id [ad_conn untrusted_user_id]
+        } on error {errorMsg} {
+          set :untrusted_user_id ${:user_id}
         }
       } else {
         set :user_id 0
@@ -347,12 +349,12 @@
     } else {
       # for requests bypassing the ordinary connection setup (resources in oacs 5.2+)
       # we have to get the user_id by ourselves
-      if { [catch {
+      ad_try {
         set cookie_list [ad_get_signed_cookie_with_expr "ad_session_id"]
         set cookie_data [split [lindex $cookie_list 0] {,}]
         set untrusted_user_id [lindex $cookie_data 1]
         set :requestor $untrusted_user_id
-      } errmsg] } {
+      } on error {errorMsg } {
         set :requestor 0
       }
     }
Index: openacs-4/packages/xotcl-core/tcl/cr-procs.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/tcl/cr-procs.tcl,v
diff -u -r1.58 -r1.59
--- openacs-4/packages/xotcl-core/tcl/cr-procs.tcl	22 Dec 2017 13:51:55 -0000	1.58
+++ openacs-4/packages/xotcl-core/tcl/cr-procs.tcl	24 Dec 2017 12:28:07 -0000	1.59
@@ -546,8 +546,10 @@
   } {
     :get_context package_id creation_user creation_ip
     #my log "ID [self] create $args"
-    if {[catch {set p [:create ::0 {*}$args]} errorMsg]} {
-      ad_log error $errorMsg
+    ad_try {
+      :create ::0 {*}$args
+    } on error {errorMsg} {
+      ad_log error "CrClass create raises: $errorMsg"
     }
     #my log "ID [::0 serialize]"
     set item_id [::0 save_new \
Index: openacs-4/packages/xotcl-core/www/admin/toggle-debug.tcl
===================================================================
RCS file: /usr/local/cvsroot/openacs-4/packages/xotcl-core/www/admin/toggle-debug.tcl,v
diff -u -r1.2 -r1.3
--- openacs-4/packages/xotcl-core/www/admin/toggle-debug.tcl	7 Aug 2017 23:48:30 -0000	1.2
+++ openacs-4/packages/xotcl-core/www/admin/toggle-debug.tcl	24 Dec 2017 12:28:07 -0000	1.3
@@ -57,9 +57,11 @@
 }
 set cmd [list {*}$scope ::nsf::method::property $obj {*}$modifier $method debug [expr {!$debug_p}]]
 ns_log notice "setting debug flag with cmd\n$cmd"
-if {[catch {ns_eval {*}$cmd} errorMsg] } {
+ad_try {
+    ns_eval {*}$cmd
+} on error {errorMsg} {
     ns_log notice "toggle-debug raised error: $errorMsg"
 }
-ns_log notice "calling return redirect to $return_url"
 
+ns_log notice "calling return redirect to $return_url"
 ad_returnredirect $return_url