Hello all,
Recently I got the error described at
Warning: toplevel constant XYZ referenced Admin:XYZ - RSpec - Ruby-Forum,
which shows that classes can’t be used to scope another classes or
modules.
Then I started thinking: why two concepts, class and module, instead of
only one?
Classes heritage, a feature modules don’t have, can be done with include
and extend togheter. So we would need another method that does both
include and extend (call it inherit). Classes can’t be used to define a
scope.
Modules can’t be instanciated, but classes can.
So why not have only one concept that does both class and modules? You
may call this unified concept either class or a module, I’ll call it X.
X is capable of extending, including and inheriting, does scoping and be
instanciated.
How does it sound?
regards,
bráulio
On Jul 23, 2013, at 16:04 , Brulio B. [email protected]
wrote:
Recently I got the error described at
Warning: toplevel constant XYZ referenced Admin:XYZ - RSpec - Ruby-Forum,
which shows that classes can’t be used to scope another classes or
modules.
that’s simply not true.
Am 24.07.2013 01:04, schrieb Bráulio Bhavamitra:
Classes heritage, a feature modules don’t have, can be done with include
How does it sound?
That sounds like: We have two different things that behave differently
and serve different purposes. Why don’t we replace them by one thing.
Not very convincing to me… 
And you forgot to mention: classes can inherit only from a single other
class (a conscious decision by Matz), but you can include many modules.
Seems difficult to unify that in one concept.
Regards,
Marcus
Am 24.07.2013 14:35, schrieb Josh C.:
C1 = Class.new Object
C2 = Class.new C1
C3 = Class.new C2
I was alluding to multiple inheritance, meaning a class
inherits directly from more than one superclass.
M1 = Module.new
M2 = Module.new
C4 = Class.new { include M2, M1 }
Regards,
Marcus
Ryan D. wrote in post #1116443:
On Jul 23, 2013, at 16:04 , Brulio B. [email protected]
wrote:
Recently I got the error described at
Warning: toplevel constant XYZ referenced Admin:XYZ - RSpec - Ruby-Forum,
which shows that classes can’t be used to scope another classes or
modules.
that’s simply not true.
So why in rails activerecord is defined as ActiveRecord::Base instead of
just ActiveRecord?
On Wed, Jul 24, 2013 at 1:10 AM, [email protected] wrote:
And you forgot to mention: classes can inherit only from a single other
class (a conscious decision by Matz), but you can include many modules.
Seems difficult to unify that in one concept.
That seems inaccurate to me:
C1 = Class.new Object
C2 = Class.new C1
C3 = Class.new C2
M1 = Module.new
M2 = Module.new
C4 = Class.new { include M2, M1 }
unknown wrote in post #1116513:
Am 24.07.2013 14:35, schrieb Josh C.:
C1 = Class.new Object
C2 = Class.new C1
C3 = Class.new C2
I was alluding to multiple inheritance, meaning a class
inherits directly from more than one superclass.
The point is that inheritance may be done with include + extend from a
module.
In fact, many libraries already prefer include/extend from module than
heritage. See MongoMapper for example.
M1 = Module.new
M2 = Module.new
C4 = Class.new { include M2, M1 }
Regards,
Marcus
X is capable of extending, including and inheriting, does scoping and be
instanciated.
I’ll give some extra explanation with an example.
With today’s model of inheritance, sometimes you get stuck with the
parent class and is forced to move methods to a module and
include/extend them.
So instead of inheritance in class definition (with the <), I propose a
method inherit, which does both include and extend.
x A
inherit D
extend C
… class and instance methods …
end
x B
include C
… class and instance methods …
end
x C
… class and instance methods …
end
x D
… class and instance methods …
end
On Wed, Jul 24, 2013 at 7:51 AM, [email protected] wrote:
Seems difficult to unify that in one concept.
inherits directly from more than one superclass.
I still don’t understand. I showed that you can inherit from multiple
classes like you can inherit from multiple modules. Yes there are other
differences, but this does not seem to be one of them. Perhaps you think
that modules have some sort of fancier inheritance? If so, this is not
the
case. When you include a module, an anonymous class with the module’s
methods gets inserted as the superclass.
On Wed, Jul 24, 2013 at 3:34 PM, Josh C. [email protected]
wrote:
class (a conscious decision by Matz), but you can include many
I was alluding to multiple inheritance, meaning a class
inherits directly from more than one superclass.
I still don’t understand. I showed that you can inherit from multiple
classes like you can inherit from multiple modules. Yes there are other
differences, but this does not seem to be one of them. Perhaps you think
that modules have some sort of fancier inheritance? If so, this is not the
case. When you include a module, an anonymous class with the module’s
methods gets inserted as the superclass.
You cannot extend from arbitrary classes. If I want to create a class
that extends String and Hash, for example, I can’t.
On the other hand I can extend any number of arbitrary modules.
Jesus.
On Wed, Jul 24, 2013 at 10:25 AM, Jess Gabriel y Galn <
[email protected]> wrote:
other
case. When you include a module, an anonymous class with the module’s
methods gets inserted as the superclass.
You cannot extend from arbitrary classes. If I want to create a class
that extends String and Hash, for example, I can’t.
On the other hand I can extend any number of arbitrary modules.
Jesus.
I’m not sure that’s what he was trying to say.
Am 24.07.2013 14:59, schrieb Bráulio Bhavamitra:
module.
But that is not the same as subclassing.
In fact, many libraries already prefer include/extend from module than
heritage. See MongoMapper for example.
Both approaches have their own use cases.
Regards,
Marcus
Am 24.07.2013 15:34, schrieb Josh C.:
And you forgot to mention: classes can inherit only from a
C3 = Class.new C2
I was alluding to multiple inheritance, meaning a class
inherits _directly_ from more than one superclass.
I still don’t understand. I showed that you can inherit from multiple
classes like you can inherit from multiple modules. Yes there are other
No, they behave differently!
The modules are not superclasses of the classes they are mixed into:
C1 = Class.new Object
C2 = Class.new C1
C3 = Class.new C2
C3.superclass # => C2
C3.superclass.superclass # => C1
M1 = Module.new
M2 = Module.new
C4 = Class.new { include M2, M1 }
C4.superclass # => Object
On Wed, Jul 24, 2013 at 12:54 PM, [email protected] wrote:
C2 = Class.new C1
No, they behave differently!
The modules are not superclasses of the classes they are mixed into:
They are, the code examples just say otherwise because Ruby lies to you.
It’s the same as how the singleton class is actually the object’s class,
even though when you ask it about its class, it will tell you what it
was
instantiated from.
This used to be a good blog about it
http://web.archive.org/web/20110214135710/http://carboni.ca/blog/p/Modules-How-Do-They-Workbut
sadly it’s down now, so you can’t see the images.
-Josh
On Wed, Jul 24, 2013 at 9:54 AM, Bráulio Bhavamitra
[email protected]wrote:
C2 = Class.new C1
https://github.com/stomar/
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On Wed, Jul 24, 2013 at 9:48 AM, Bráulio Bhavamitra
[email protected]wrote:
Warning: toplevel constant XYZ referenced Admin:XYZ - RSpec - Ruby-Forum,
–
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ideologia. Morra por sua ideologia” P.R. Sarkar
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–
“Lute pela sua ideologia. Seja um com sua ideologia. Viva pela sua
ideologia. Morra por sua ideologia” P.R. Sarkar
EITA - Educação, Informação e Tecnologias para Autogestão