Newsgroups: comp.lang.smalltalk
Path: utzoo!utgpu!cunews!knight
From: knight@mrco.carleton.ca (Alan Knight)
Subject: Re: Access methods - New feature ?
Message-ID: <1991Apr22.130452.6181@ccs.carleton.ca>
Summary: Can be done
Keywords: Access methods, Smalltalk-80
Sender: news@ccs.carleton.ca (news)
Organization: Carleton University, Ottawa, Canada
References: <1991Apr21.221149.8057@vuse.vanderbilt.edu> <1991Apr22.003659.18658@ux1.cso.uiuc.edu> <2270@media03.UUCP>
Date: Mon, 22 Apr 1991 13:04:52 GMT

In article <2270@media03.UUCP> pkr@media03.UUCP (Peter Kriens) writes:
>Dan Walkowski writes:
>> If access methods were automatically generated for every private variable,
>> then this breaks down; every object can diddle with the state of every other.
>> Yes, frequently you need to write several access methods for several private
>> variables of an object, but if you are finding that you need to make ALL of

<stuff omitted>

>Eiffel has a very nice solution for this. It allows an instance variable
>to be exported in the header (Smalltalk could also do that in the
>class definition, you could for example place a colon behinde the 
>definition of the instance variable). So in Eiffel you can easely access those often
>used instance variables. The good thing is that if you decide later on
>to replace the instance access with a procedure, because the implementation
>changes, nobody notices because the syntax stays the same. Sounds like
>a feature I could love in Smalltalk. Unfortunately you cannot access the
>compiler in Digitalk smalltalk, otherwise it could be done.
>
>Peter Kriens
>pkr@media01

A nearly equivalent feature, and one which preserves a little more
encapsulation than automatically writing all acces methods is to allow
them to be written on command, one at a time.  i.e. have a menu item
which writes access methods for a single instance variable.  I've seen
this done in Smalltalk/V, and it could easily be done in Smalltalk-80.
  
   The disadvantage of this method is that it discourages comments,
particularly a problem in /V where there are no class comments.
Coming across the automatically written message

glorch: aValue
   "Set the value of the instance variable glorch to aValue"

    glorch := aValue.

is annoying (to say the least), when there is no indication what kind of
a thing glorch is or what it is used for.

-- 
--
  Alan Knight   knight@mrco.carleton.ca  +1 613 788 5783   Support
  Dept. of Mechanical and Aeronautical Engineering         the
  Carleton University, Ottawa, Ontario, Canada, K1S 5B6    LPF