Slots doc

Seems like an opportunity...I have no idea what the addition of slots does but I would like to learn.

On Feb 3, 2019, at 1:33 AM, ducasse <[hidden email]> wrote:

Hello,

Where I can find documentation for slots?

I am trying to access the pharo books site but it is unreachable from my
network right now, I got a connection time out (It works from my 3G though
(??) ), but if I remember correctly the is no slot description in any book.

Regards,
Vitor

Hello victor 

There is no documentation about slots that I know. I’m sorry. 

Marcus may want to write one in the future.

Stef

On 6 Feb 2019, at 13:25, Vitor Medina Cruz <[hidden email]> wrote:

Thanks, I was looking for usages of InstanceVariableSlot.

All instance variables are InstanceVariableSlots. 

But to make it less verbose, we have a way to specify these without having to put the name. 

Object subclass: #Point

slots: { #x. #y }

classVariables: {  }

package: 'Kernel-BasicObjects’

is the same as

Object subclass: #Point

slots: { #x => InstanceVariableSlot . #y => InstanceVariableSlot}

classVariables: {  }

package: 'Kernel-BasicObjects'

If you evaluate:

Point slotNamed: #x 

you see that it returns a 

    #x => InstanceVariableSlot

Slot instance.

(with all that: I sometime wonder if we should not get rid of the name “Slot” and just use the term “Variable”… because that is what they are…)

In the case of SlotExampleMovie, #name and #year are of IntanceVariableSlot layout (this definition is correct? A slot is or has some Layout defined by the Slot class?)

No, the class has a Layout. See subclasses of AbstractLayout. This reifies the magic number that is in the “format” ivar of Behaviors (third ivar of all class like objects).

In addition it makes class definition *explicitly* specify the layout.

So Array in ST 80 is something like:

ArrayedCollection variableSubclass: #Array

instanceVariableNames: ''

classVariableNames: ''

package: 'Collections-Sequenceable-Base'

so the layout chosen is hidden in the class creation method (variableSubclass…), while with the reified layouts, it explicit:

ArrayedCollection subclass: #Array

layout: VariableLayout

slots: {  }

classVariables: {  }

package: 'Collections-Sequenceable-Base’ 

e.g. for CompiledMethod it makes clear that is a very special class:

CompiledCode subclass: #CompiledMethod

layout: CompiledMethodLayout

slots: {  }

classVariables: {  }

package: 'Kernel-Methods’

On Wed, Feb 6, 2019 at 10:14 AM Marcus Denker <[hidden email]> wrote:

> On 6 Feb 2019, at 12:41, Denis Kudriashov <[hidden email]> wrote:
>
> Would be nice to have a command in browser to show users of selected slot
>

Yes!

        Marcus