[Newbies] My customisation conundrum

[Alain Plantec]

On Thursday 26 June 2008 13:07:04 Nick Smith wrote:
> 
> I'm a newbie to programming and I'm really enjoying learning Squeak, Seaside. 
> One of the biggest delights for me is discovering just how expressive and
> powerful Smalltalk is when you can so easily add your own methods to the
> base classes.  By using good intention-revealing selector names, I can write
> code that is almost self-explanatory.... like prose but not in the language
> of Smalltalk, in the language of the application/problem domain itself. 
> This is brilliant.  Every program you write is it's own DSL.
> 
> So here's the thing I don't yet understand.  If I embrace this way of
> programming and extend bases classes by adding my own methods, what happens
> to those methods when I upgrade my image to a newer version of Squeak?  Is
> it that I need to subclass existing base classes before extending them (to
> better separate my code from the original) or perhaps I need to learn to use
> Traits; or is there something about Monticello that allows me to migrate my
> custom methods to newer images?  Or maybe perhaps there's something I've
> missed completely.

You can use changes set or packages (with Monticello).
It seems to me that Monticello is what you are looking for. 

By convention, a package XXX owns all classes that are 
defined within a system category which name start with 'XXX-'
and owns all methods that are defined within a method category 
which name start with '*xxx-'.

Let's try following example:

- Create a class A with 'XXX-base' as its system category 
  and a class B with 'XXX-util' as its system category.
- Open Monticello, click on '+package' button and type 'XXX'. 
- Then select and browse XXX package ('Browse' button).
  A package browser is opened on XXX package (showing your two system 
  categories 'XXX-base' and 'XXX-util').

- Now Browse class String with a standard browser, create a 
  method category named '*xxx-for-my-test' 
  (don't forget the $* at the beginning of the category name).
- Create a method within '*xxx-for-my-test', as an example:
  forMyTest
     ^ self

- Then, open Monticello and browse your package again.
  On left package browser list, select '*Extensions' item.
  you should see your String>>forMyTest method in.
  This means that String>>forMyTest owns to XXX package. Yes! you got it!
  (this was the main subject of your question I guess).

Now the question is, how to save a package and import it 
from another squeak image.
- For file out, select your package from Monticello then 
  select a repository (at least the local one is present)
  and click on 'Save' button.
- Then open a file list and browse 'package-cache' sub directory.
  you should see a file named 'XXX.<your-initials>.1.mcz'. 
  This is your XXX package.

- Then open another squeak image (a fresh one, without XXX package).
- Open a file list, browse 'package-cache' sub directory, 
  select 'XXX.<your-initials>.1.mcz'
  and click on 'Load' button. 

After that, your package is loaded, comprising extension 
methods (your String>>forMyTest).

Cheers
alain


 



















 

> 
> Thanks.