Path: utzoo!utgpu!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!rutgers!uwvax!tank!uxc!uxc.cso.uiuc.edu!m.cs.uiuc.edu!p.cs.uiuc.edu!johnson
From: johnson@p.cs.uiuc.edu
Newsgroups: comp.lang.smalltalk
Subject: Re: Quest. on Smalltalk
Message-ID: <80500047@p.cs.uiuc.edu>
Date: 17 Dec 88 20:44:00 GMT
References: <14@<Dec>
Lines: 15
Nf-ID: #R:<Dec:14:p.cs.uiuc.edu:80500047:000:758
Nf-From: p.cs.uiuc.edu!johnson    Dec 17 14:44:00 1988


>1. Is it possible to create a message at run time and then send it?
>For those of you who know LISP, I am asking if Smalltalk has a
>facility analogous to the EVAL statement.

If you really want to define a new method at run time, then perform:
will not do the trick.  You can build up a string and send a message
to a class asking it to install it as a new method, or you can just
ask the compiler to evaluate it for you.  It is instructive to see
how doIt is implemented in TextController. (Unless it is done in
ParagraphEditor.  I think it is in TextCOntroller, though.)

In general, however, perform: is safer and will probably do what
you want.  Blocks can also often be used as the solution to problems
of this type, as Scheme programmers well know.