On Sun, Feb 10, 2013 at 8:42 AM, Frank Shearar <frank.shearar at gmail.com>wrote:

> On 10 February 2013 16:25, Camillo Bruni <camillobruni at gmail.com> wrote:
> > Why does SystemNavigation >> #allSelect: return strings of the form
> 'Array at:' instead of the real methods?
>
> Probably because the things that use SystemNavigation - Browsers,
> MessageSets and the like - want to render lists of things to the user.
>
> There is one advantage to dumb strings, which is that it's easy to
> make a SystemNavigation that works against a remote image. But that's
> not much to go on. Changing these kinds of methods to return
> MethodReferences might be a useful middle ground (and permit easy
> extension to remote tools).
>

No, dumb strings are dumb.  A className, selector pair (which is what
MethodReference is) is the right thing (and what systemNavigation methods
return).  The dumb strings are a pain in the ass to parse (endlessly
looking for ' class' to spot meta classes etc).  Whereas the class,selector
p[air approach is extensible, e.g. to include a pointer to a specific
external entity (be it Monticello package or remote image).
 MethodReference is what the system has provided for a decade and they're
convenient.  There are multiple versions of these and I could care less
about whether one uses MethodReference or RBMethodDefinition.  But that
they have a consistent API is really important.  Programmatic uses of these
things for code editing is something I've depended upon in the VMMaker, and
I'm anxious that Pharo and Squeak don't diverge hopelssly on this level of
the system.

In my own work I've ended up with three kinds of code reference object

a) MethodReference that points to a class,selector pair
b) ClassReference that points to a class
c) TextReference that holds onto a text

So if one wants to check out a refactoring/edit before applying it one
compares a sequence of MethodReference objects and a matching sequence of
TextReference objects that hold onto the edited source to a comparison
engine.

If one wants to have a look at all uses of a SharedPool one can supply a
list of ClassReference objects to a list browser.

If one wanted to build a "compare two images" or "compare arbitrary package
versions: facility one can extend the reference objects with pointers to
specific packages or remote images.

etc.

Lots of stuff in the system depends on these kinds of pointer; message list
browsers, Monticello's loader, etc.

What's insane is a) not having a standard set of facilities common between
Pharo and Squeak with a well-defined API (e.g. isCodeReference,
isMethodReference, isClassReference), b) having some of the API in
extension methods in e.g. Monticello.

This is core reflection protocol and it needs to be well-defined and in
what ever package contains base reflection protocol.


excuse my ranting.


> I mention remote tools because I hacked up a proof of concept a while
> back that turned a Browser into one that could access a suitably
> prepared image through an HTTP API. Development stalled because the
> reflection machinery's API is a bit... involved, and it was dog slow,
> but I could browse anything I liked. I should really wrap up the work
> a bit so I can spread the love.
>
> frank
>
>


-- 
best,
Eliot
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