Hi all,

I recorded a little screencast of the EnvironmentBrowser I've been 
playing with:

https://www.youtube.com/watch?v=1UOyca5-72Y

it's ~11 minutes long if you watch it at 1:1. In the description of the 
video is the outline that I was following as I recorded the talk.

I'll paste it below as well.

Cheers,
   Tony

-=-=-=-=-

[Here's the outline I was following as I recorded this talk.]

Hi everyone.

I'm Tony Garnock-Jones, it's March 30th 2021, and I'm going to walk 
through the experimentation I've been doing on nested Namespaces in 
Squeak Smalltalk.

This work builds on Squeak's Environments, which I think are originally 
due to Colin Putney with some recent work by Jakob Reschke.

I've made some small additions to Environment, and a little subclass 
called Namespace, which allows one to expose Environments via ordinary 
variable reference, if one so chooses. It doesn't change anything about 
how Environments work otherwise, so existing uses should remain unchanged.

I've also added a variant of Browser that shows these accessible 
Environments in a hierarchy, and allows you to manage their imports and 
exports. Here it is.

[Open an EnvironmentBrowser]
[Navigate to EnvironmentBrowser]

The tool is called EnvironmentBrowser, and it's a very thin veneer over 
the existing underlying Environment machinery.

You can see that compared to the default browser, it has a couple of 
extra panels.

This one [on the left] is a tree of environments. The idea is to take 
Environment's Instances as "well-known" roots for this tree:

   Environment wellKnownInstances

Smalltalk is already in there, and at the moment there are no others.

 From the roots, we recursively scan each environment for globals that 
are also Environments. This scan is a part of Environment itself:

[Navigate to Environment's namespaceTreeDo: method]

This other panel [on the left, just below the tree of environments] 
shows the imports and exports of this environment.

Here you can see that the default environment, Smalltalk, imports all 
its own bindings, so they're visible to its own classes, and exports all 
its bindings to other Environments that import from Smalltalk.

[Create namespace NS1]
[Create class String, extends Object, inst var length, category Demo]
[Create accessors]

printOn: aStream
	aStream nextPutAll: 'I am a ball of wool ', length, ' metres long'

[class side]
new: size
	^ self new length: size
[Proceed on the warning]

[Open workspace in Smalltalk]
String new: 3

[Open workspace in NS1]
String new: 3

[Rename NS1 to Fabric]
[Create namespace NS2]
[Import Fabric with prefix Fabric]

[Open workspace in NS2]
String new: 3
FabricString new: 3
"Oh! It didn't work! We didn't export it from Fabric."

[Export all from Fabric]
[Try again - still doesn't work]
[Redo the import]
[Try again - works now!]

There are still some issues with, I think, Environments themselves 
propagating changes to each other.

Fabric String new: 3

[Unlink Fabric]

Now we see:

String new: 3
FabricString new: 3
Fabric String new: 3  "error on this, Fabric is missing"

[Remove the policy importing Fabric to NS2]

Didn't remove it. Still some bugs.