--- a/libinterp/interpfcn/input.cc
+++ b/libinterp/interpfcn/input.cc
@@ -49,6 +49,7 @@
 #include "error.h"
 #include "gripes.h"
 #include "help.h"
+#include "hook-fcn.h"
 #include "input.h"
 #include "lex.h"
 #include "load-path.h"
@@ -121,250 +122,6 @@
 // The filemarker used to separate filenames from subfunction names
 char Vfilemarker = '>';
 
-class
-base_hook_function
-{
-public:
-
-  friend class hook_function;
-
-  base_hook_function (void) : count (1) { }
-
-  base_hook_function (const base_hook_function&) : count (1) { }
-
-  virtual ~base_hook_function (void) { }
-
-  virtual std::string id (void) { return std::string (); }
-
-  virtual bool is_valid (void) { return false; }
-
-  virtual void eval (const octave_value_list&) { }
-
-protected:
-
-  size_t count;
-};
-
-class
-hook_function
-{
-public:
-
-  hook_function (void)
-  {
-    static base_hook_function nil_rep;
-    rep = &nil_rep;
-    rep->count++;
-  }
-
-  hook_function (const octave_value& f,
-                 const octave_value& d = octave_value ());
-
-  ~hook_function (void)
-  {
-    if (--rep->count == 0)
-      delete rep;
-  }
-
-  hook_function (const hook_function& hf)
-    : rep (hf.rep)
-  {
-    rep->count++;
-  }
-
-  hook_function& operator = (const hook_function& hf)
-  {
-    if (rep != hf.rep)
-      {
-        if (--rep->count == 0)
-          delete rep;
-
-        rep = hf.rep;
-        rep->count++;
-      }
-
-    return *this;
-  }
-
-  std::string id (void) { return rep->id (); }
-
-  bool is_valid (void) { return rep->is_valid (); }
-
-  void eval (const octave_value_list& initial_args)
-  {
-    rep->eval (initial_args);
-  }
-
-private:
-
-  base_hook_function *rep;
-};
-
-class
-named_hook_function : public base_hook_function
-{
-public:
-
-  named_hook_function (const std::string& n, const octave_value& d)
-    : name (n), data (d)
-  { }
-
-  void eval (const octave_value_list& initial_args)
-  {
-    octave_value_list args = initial_args;
-
-    if (data.is_defined ())
-      args.append (data);
-
-    feval (name, args, 0);
-  }
-
-  std::string id (void) { return name; }
-
-  bool is_valid (void) { return is_valid_function (name); }
-
-private:
-
-  std::string name;
-
-  octave_value data;
-};
-
-class
-fcn_handle_hook_function : public base_hook_function
-{
-public:
-
-  fcn_handle_hook_function (const octave_value& fh_arg, const octave_value& d)
-    : ident (), valid (false), fcn_handle (fh_arg), data (d)
-  {
-    octave_fcn_handle *fh = fcn_handle.fcn_handle_value (true);
-
-    if (fh)
-      {
-        valid = true;
-
-        std::ostringstream buf;
-        buf << fh;
-        ident = fh->fcn_name () + ":" + buf.str ();
-      }
-  }
-
-  void eval (const octave_value_list& initial_args)
-  {
-    octave_value_list args = initial_args;
-
-    if (data.is_defined ())
-      args.append (data);
-
-    fcn_handle.do_multi_index_op (0, args);
-  }
-
-  std::string id (void) { return ident; }
-
-  bool is_valid (void) { return valid; }
-
-private:
-
-  std::string ident;
-
-  bool valid;
-
-  octave_value fcn_handle;
-
-  octave_value data;
-};
-
-hook_function::hook_function (const octave_value& f, const octave_value& d)
-{
-  if (f.is_string ())
-    {
-      std::string name = f.string_value ();
-
-      rep = new named_hook_function (name, d);
-    }
-  else if (f.is_function_handle ())
-    {
-      rep = new fcn_handle_hook_function (f, d);
-    }
-  else
-    error ("invalid hook function");
-}
-
-class
-hook_function_list
-{
-public:
-
-  typedef std::map<std::string, hook_function> map_type;
-
-  typedef map_type::iterator iterator;
-  typedef map_type::const_iterator const_iterator;
-
-  hook_function_list (void) : fcn_map () { }
-
-  ~hook_function_list (void) { }
-
-  hook_function_list (const hook_function_list& lst)
-    : fcn_map (lst.fcn_map)
-  { }
-
-  hook_function_list& operator = (const hook_function_list& lst)
-  {
-    if (&lst != this)
-      fcn_map = lst.fcn_map;
-
-    return *this;
-  }
-
-  bool empty (void) const { return fcn_map.empty (); }
-
-  void clear (void) { fcn_map.clear (); }
-
-  void insert (const std::string& id, const hook_function& f)
-  {
-    fcn_map[id] = f;
-  }
-
-  iterator find (const std::string& id)
-  {
-    return fcn_map.find (id);
-  }
-
-  const_iterator find (const std::string& id) const
-  {
-    return fcn_map.find (id);
-  }
-
-  iterator end (void) { return fcn_map.end (); }
-
-  const_iterator end (void) const { return fcn_map.end (); }
-
-  void erase (iterator p) { fcn_map.erase (p); }
-
-  void run (const octave_value_list& initial_args = octave_value_list ())
-  {
-    iterator p = fcn_map.begin ();
-
-    while (p != fcn_map.end ())
-      {
-        std::string hook_fcn_id = p->first;
-        hook_function hook_fcn = p->second;
-
-        iterator q = p++;
-
-        if (hook_fcn.is_valid ())
-          hook_fcn.eval (initial_args);
-        else
-          fcn_map.erase (q);
-      }
-  }
-
-private:
-
-  map_type fcn_map;
-};
-
 static hook_function_list pre_input_event_hook_functions;
 static hook_function_list input_event_hook_functions;
 static hook_function_list post_input_event_hook_functions;

--- a/libinterp/interpfcn/module.mk
+++ b/libinterp/interpfcn/module.mk
@@ -11,6 +11,7 @@
   interpfcn/error.h \
   interpfcn/file-io.h \
   interpfcn/help.h \
+  interpfcn/hook-fcn.h \
   interpfcn/input.h \
   interpfcn/load-path.h \
   interpfcn/load-save.h \