programmatic application of properties: error out if no *CONNECTION*

Signed-off-by: Sean Whitton <spwhitton@spwhitton.name>

1 files changed, 7 insertions, 0 deletions

diff --git a/src/property.lisp b/src/property.lisp
index e846c46..b43fe8c 100644
--- a/src/property.lisp
+++ b/src/property.lisp
@@ -300,6 +300,13 @@ parsing FORMSV and pushing SETPROP keyword argument pairs to plist SLOTSV."
                   ,@(and
                      (getf ,slotsv :apply)
                      `((defun-with-args ,,namev args ,,lambdav
+                         (unless *connection*
+                           (simple-program-error
+"Attempt to programmatically apply property with no connection established.
+
+Common causes of this error are (i) missing the '.' to enable the dotted
+propapp rules; and (ii) inadvertently calling the contents of a property's
+function cell, instead of constructing a propapp, within DEFPROPSPEC."))
                          ;; Properties with :HOSTATTRS subroutines which set
                          ;; new hostattrs should not be used programmatically
                          ;; in this way, so issue a warning.