There is another approach available in Smalltalk that is not available in
many other languages.  The syntax of Smalltalk as is allows for a pretty
good DSL to be built out of simple classes and blocks with good selector
naming.  You really do not need to dynamically add code to the system to get
a DSL when the syntax for Smalltalk is so flexible and has good readability.
You can certainly do "modeling" and generate the code from some other
representation.  But, then you lose all the value of the Smalltalk tools.
If the user wants to model orders just create an Order class and let them go
to town with Orderish methods and blocks.  Then they can use the best
debugger on the planet (that actually works when you want to change the
source, etc).  You can even persist in-flight execution and many other
things that other environments do not support, letting that DSL support more
than just in-memory execution.  Integrating database accesses and
distributed communications is not a barrier.

Michael

-----Original Message-----
From: squeak-dev-bounces at lists.squeakfoundation.org
[mailto:squeak-dev-bounces at lists.squeakfoundation.org] On Behalf Of Rich
Warren
Sent: Wednesday, August 16, 2006 6:56 PM
To: The general-purpose Squeak developers list
Subject: Re: Info on Smalltalk DSLs or Metaprogramming...

In my tests, I've noticed that Behavior>>compile: actually changes  
the image. Is there any way to make less-permanent changes (e.g. just  
changing a single instance)?

-Rich-


On Aug 14, 2006, at 6:55 AM, Wilkes Joiner wrote:

> Here is a blog entry of mine about using the Refactoring Browsers code
> to generate classes for me:
>
> http://wilkes.blogspot.com/2005/12/simple-code-generation-in- 
> smalltalk.html
>
> The Behavior>>compile: method will add a new method onto a class.
>
> For instance methods:
> MyClass compile: 'someAttribute
>    ^ someAttribute'
>
> For class methods:
> MyClass class compile: 'aClassMethod
>   "Do some stuff"'
>
>
> On 8/14/06, Rich Warren <rwmlist at gmail.com> wrote:
>> Hi,
>>
>> I've seen several online articles about writing Domain Specific
>> Languages in Ruby. All the articles mention that the idea of DSLs
>> comes largely from Lisp and Smalltalk. I've found descriptions on
>> writing DSLs in Lisp--but I can't seem to find any good references
>> for Smalltalk.
>>
>> Does anyone have any helpful pointers? If I'm going to follow the
>> Ruby model, then I need to be able to execute arbitrary strings as
>> code (which Compiler evaluate: and related functions seems to
>> handle). I also need to be able to add new methods to classes/
>> instances at runtime--which I haven't found.
>>
>> Any help would be greatly appreciated.
>>
>> -Rich-
>>
>>
>