Pharo and instance variables ...

On Wed, Oct 18, 2017 at 7:07 AM, James Ladd <[hidden email]> wrote:

Hey David,

If you could only access instance variables in the class that defined them and therefore only in a subclass via an accessor / mutator method w that be a big problem in your view?

Yes.

I don't want to have to define accessors, which are public, just to have the subclasses access the instance variables.

 

Sent from my Commodore 64

On 18 Oct 2017, at 2:41 pm, David Mason <[hidden email]> wrote:

In Pharo, open a browser on OrderedCollection, then click "Variables" in the top left of the window and then "array"... if you scroll through you can see that mostly OrderedCollection methods use it, but some SortedCollection (a subclass) methods also use it.

The model is similar to protected in Java (see http://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html ) except there is no "Package" column.

On 17 October 2017 at 23:30, James Ladd <[hidden email]> wrote:

Please could you provide an example?

On Wed, Oct 18, 2017 at 2:16 PM, David Mason <[hidden email]> wrote:

Any instance method in the class where the instance variable is defined or in a subclass can access the instance variable.  Similarly for class methods to access class-side variables, and for class and instance methods to access class variables.

On 17 October 2017 at 23:04, James Ladd <[hidden email]> wrote:

Hello Pharo Users,

I'm wondering about instance variables for support in Redline Smalltalk and
want to get my understanding straight.

Are instance variables only accessible (without using #instVarNamed:) inside
the method with the same name as the instance variable?

eg:

   myInstVar
   ^ myInstVar.

Or can you reference an instance variable from a method that doesn't have
the same name ?

   anotherMethod
   ^ myInstVar.

Can someone give me or point me to an example of accessing an instance
variable in Pharo Smalltalk?

- James.




--
Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

--

Clément Béra

Pharo consortium engineer

https://clementbera.wordpress.com/

Bâtiment B 40, avenue Halley 59650 Villeneuve d'Ascq

It would break code all over the place...

What if accessors were generated but not mutators?

Sent from my Commodore 64

On 18 Oct 2017, at 4:21 pm, Clément Bera <[hidden email]> wrote:

On Wed, Oct 18, 2017 at 7:07 AM, James Ladd <[hidden email]> wrote:

Hey David,

If you could only access instance variables in the class that defined them and therefore only in a subclass via an accessor / mutator method w that be a big problem in your view?

Yes.

I don't want to have to define accessors, which are public, just to have the subclasses access the instance variables.

 

Sent from my Commodore 64

On 18 Oct 2017, at 2:41 pm, David Mason <[hidden email]> wrote:

In Pharo, open a browser on OrderedCollection, then click "Variables" in the top left of the window and then "array"... if you scroll through you can see that mostly OrderedCollection methods use it, but some SortedCollection (a subclass) methods also use it.

The model is similar to protected in Java (see http://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html ) except there is no "Package" column.

On 17 October 2017 at 23:30, James Ladd <[hidden email]> wrote:

Please could you provide an example?

On Wed, Oct 18, 2017 at 2:16 PM, David Mason <[hidden email]> wrote:

Any instance method in the class where the instance variable is defined or in a subclass can access the instance variable.  Similarly for class methods to access class-side variables, and for class and instance methods to access class variables.

On 17 October 2017 at 23:04, James Ladd <[hidden email]> wrote:

Hello Pharo Users,

I'm wondering about instance variables for support in Redline Smalltalk and
want to get my understanding straight.

Are instance variables only accessible (without using #instVarNamed:) inside
the method with the same name as the instance variable?

eg:

   myInstVar
   ^ myInstVar.

Or can you reference an instance variable from a method that doesn't have
the same name ?

   anotherMethod
   ^ myInstVar.

Can someone give me or point me to an example of accessing an instance
variable in Pharo Smalltalk?

- James.




--
Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

--

Clément Béra

Pharo consortium engineer

https://clementbera.wordpress.com/

Bâtiment B 40, avenue Halley 59650 Villeneuve d'Ascq

On 18 Oct 2017, at 08:32 , James Ladd <[hidden email]> wrote:

What if accessors were generated but not mutators?

It would break code all over the place...

On 18/10/2017 16:02, James Ladd wrote:

What if accessors were generated but not mutators?

Sent from my Commodore 64

On 18 Oct 2017, at 4:21 pm, Clément Bera <[hidden email]> wrote:

On Wed, Oct 18, 2017 at 7:07 AM, James Ladd <[hidden email]> wrote:

Hey David,

If you could only access instance variables in the class that defined them and therefore only in a subclass via an accessor / mutator method w that be a big problem in your view?

Yes.

I don't want to have to define accessors, which are public, just to have the subclasses access the instance variables.

 

Sent from my Commodore 64

On 18 Oct 2017, at 2:41 pm, David Mason <[hidden email]> wrote:

In Pharo, open a browser on OrderedCollection, then click "Variables" in the top left of the window and then "array"... if you scroll through you can see that mostly OrderedCollection methods use it, but some SortedCollection (a subclass) methods also use it.

The model is similar to protected in Java (see http://docs.oracle.com/javase/tutorial/java/javaOO/accesscontrol.html ) except there is no "Package" column.

On 17 October 2017 at 23:30, James Ladd <[hidden email]> wrote:

Please could you provide an example?

On Wed, Oct 18, 2017 at 2:16 PM, David Mason <[hidden email]> wrote:

Any instance method in the class where the instance variable is defined or in a subclass can access the instance variable.  Similarly for class methods to access class-side variables, and for class and instance methods to access class variables.

On 17 October 2017 at 23:04, James Ladd <[hidden email]> wrote:

Hello Pharo Users,

I'm wondering about instance variables for support in Redline Smalltalk and
want to get my understanding straight.

Are instance variables only accessible (without using #instVarNamed:) inside
the method with the same name as the instance variable?

eg:

   myInstVar
   ^ myInstVar.

Or can you reference an instance variable from a method that doesn't have
the same name ?

   anotherMethod
   ^ myInstVar.

Can someone give me or point me to an example of accessing an instance
variable in Pharo Smalltalk?

- James.




--
Sent from: http://forum.world.st/Pharo-Smalltalk-Users-f1310670.html

--

Clément Béra

Pharo consortium engineer

https://clementbera.wordpress.com/

Bâtiment B 40, avenue Halley 59650 Villeneuve d'Ascq

On 18 Oct 2017, at 08:32 , James Ladd <[hidden email]> wrote:

What if accessors were generated but not mutators?

The point is that, once a method exists, there is not way to restrict who can send a message that will execute it.  So if one were forces to generate a reader method, or a writer method, just to give access to a subclass, then every object n the system would also gain access.

Andrew