throw error when trying to set or append the string part of "*" and appending to "$"

 * these operations are unsupported and there is no benefit
   in ignoring them silently. It only confused the user.

3 files changed, 28 insertions, 3 deletions

diff --git a/doc/sciteco.7.template b/doc/sciteco.7.template
index 8272b08..1e3739a 100644
--- a/doc/sciteco.7.template
+++ b/doc/sciteco.7.template
@@ -1017,6 +1017,7 @@ always have forward-slash directory separators even if they
 are displayed differently in the user interface.
 The \(lq*\(rq register may also be edited but changing its
 string contents has no effect on the file name of the buffer.
+Setting and appending to the \(lq*\(rq register is unsupported.
 Setting the numeric part of the \(lq*\(rq register,
 as in \(lq1U*\(rq, is equivalent to editing a buffer by id
 (e.g. \(lq1EB\fB$\fP\(rq) but is shorter since there is no
@@ -1048,6 +1049,7 @@ but querying \(lq$\(rq will still return an absolute path.
 The \(lq$\(rq register may also be edited but changing its
 string contents this way has no effect on the current
 working directory.
+Appending to the \(lq$\(rq register is unsupported.
 .TP
 .BR $ " (Escape)"
 Command-line replacement register.
diff --git a/src/error.h b/src/error.h
index c9cad00..26c98f6 100644
--- a/src/error.h
+++ b/src/error.h
@@ -193,6 +193,14 @@ public:
 				local ? "." : "", name) {}
 };
 
+class QRegOpUnsupportedError : public Error {
+public:
+	QRegOpUnsupportedError(const gchar *name, bool local = false)
+	                      : Error("Operation unsupported on "
+	                              "Q-Register \"%s%s\"",
+	                              local ? "." : "", name) {}
+};
+
 } /* namespace SciTECO */
 
 #endif
diff --git a/src/qregisters.h b/src/qregisters.h
index 1ef0564..2933dc8 100644
--- a/src/qregisters.h
+++ b/src/qregisters.h
@@ -28,6 +28,7 @@
 #include <Scintilla.h>
 
 #include "sciteco.h"
+#include "error.h"
 #include "interface.h"
 #include "ioview.h"
 #include "undo.h"
@@ -177,9 +178,18 @@ public:
 
 	tecoInt get_integer(void);
 
-	void set_string(const gchar *str, gsize len) {}
+	void
+	set_string(const gchar *str, gsize len)
+	{
+		throw QRegOpUnsupportedError(name);
+	}
 	void undo_set_string(void) {}
-	void append_string(const gchar *str, gsize len) {}
+
+	void
+	append_string(const gchar *str, gsize len)
+	{
+		throw QRegOpUnsupportedError(name);
+	}
 	void undo_append_string(void) {}
 
 	gchar *get_string(void);
@@ -195,7 +205,12 @@ public:
 
 	void set_string(const gchar *str, gsize len);
 	void undo_set_string(void);
-	void append_string(const gchar *str, gsize len) {}
+
+	void
+	append_string(const gchar *str, gsize len)
+	{
+		throw QRegOpUnsupportedError(name);
+	}
 	void undo_append_string(void) {}
 
 	gchar *get_string(void);