...applications.

The author is aware of two general extension environments: Bob Glickstein's ELI---The Embedded Lisp Interpreter from Carnegie-Mellon University, and Oliver Laumann's ELK---The Extensible Lisp Kernel from Technical University of Berlin, which is based on Scheme. At the time of writing this paper, nothing seems to have been published about these systems.

...methods.

On purpose, we do not mention the around methods, because they rely on an imperative combination with before, primary, and after methods in standard method combination. This is analogous to the method combination in Smalltalk, which is explicitly programmed from case to case, by sending messages to super.

...executed.

It is worth comparing our approach to the approach used in Pan, which we described in section 2 of this paper. In Pan, hook definition and hook execution are separated into two constructs, which are called define-hook and perform-hook respectively.

...procedure

In Lisps in which procedures are not first class objects, one may prefer to use procedure names in hook-attach and hook-detach.

...applications

The hook combinator mechanism is inspired by the simple built-in method combination mechanism in CLOS [6].

...definition.

It would be possible to integrate the hook documentation clause as well as the hook combinator clause into the hook construct. Following this idea, a hook construct would consist of a name, some actual parameters, a default form, a hook combinator, and a hook documentation string. However, all these pieces of information make a typical hook construct far too big. This is a pragmatic problem that should not be underestimated. We have chosen to split the construct into several dependent constructs. Another solution would be to separate the hook definition from the execution of the hook, as it is done in Pan, see section 2. A third solution would be to use a programming environment with program presentation facilities that allow for abstract presentation[15]---in this case selective presentation---of lengthy constructs.

...expression.

This may for instance be done via an inspection hook in the read function.

...emacs

The hooks in the group emacs are the ``native hooks'' of Emacs, such as the hooks associated with major modes (see section 2). Such hooks are treated as a special case in the tools which support the notion of hooks, as defined in this paper. The advantage of this is that we are able to give the same support to Emacs hooks with respect to reporting and experimental attaching as we do to our own hooks.

...profile.

The tools get the information about the parameter profile from the hook documentation. In order for this to work, the style of the documentation is assumed to follow a standard pattern. This is made easy by providing editing operations, which defines a template of the hook-documentation construct, given a hook construct.

Kurt Noermark
Wed Mar 6 09:44:24 MET 1996