a simple question (I think)
I find myself, over and over, creating a & storing q new object in an instVar, then storing (my)self on that object - so I can have easy access to the 'object that created me.' <what I do now...> self instVar := NewClass new. self instVar callingObject: self. "where these call the same messages" self myMessage. self instVar callingObject myMessage. <is there a way to...> self instVar := NewClass new. self instVar objectWhoCreatedMe myMessage. "I know there is a 'thisContext sender' - but is there a 'who created me' concept?" Ultimately, there is no real overhead to storing (my)self on a new object, I guess, but as I'm developing and testing, I tend to have a whole lot of 'stranded objects' I have to remove manually. Thoughts? Thanks! -- Russ Whaley whaley.russ@gmail.com
Objects interact with each other by sending messages, although you can get the sender by using reflection (thisContext sender), it is not a common practice to do so. So if you need another object to know the sender (or any other object) you simply pass it as a parameter. So modifying your example, and making the syntax actually work it would be: self property: ObjectClass new. self property caller: self. and then when you need to deal with that you can simply get a reference to that object and send it a message to do something: self property caller doSomething. You can also have something like self property: (ObjectClass for: self) In that case the #for: message is received by "ObjectClass class", which you can think of as if it were a Factory or a "static" method (it is not! it is much more powerful than that). ObjectClass class>>#for: callerObject ^self new setCaller: callerObject; yourself And that's it, you have an instance of ObjectClass that you initialized by sending #for: instead of #new (internally it ended up calling #new, but from the outside it was just a message send). And for the most part that's Smalltalk: Objects and messages. Regards! Esteban A. Maringolo On Wed, Jun 17, 2020 at 6:19 PM Russ Whaley <whaley.russ@gmail.com> wrote:
I find myself, over and over, creating a & storing q new object in an instVar, then storing (my)self on that object - so I can have easy access to the 'object that created me.'
<what I do now...>
self instVar := NewClass new.
self instVar callingObject: self.
"where these call the same messages"
self myMessage.
self instVar callingObject myMessage.
<is there a way to...>
self instVar := NewClass new.
self instVar objectWhoCreatedMe myMessage.
"I know there is a 'thisContext sender' - but is there a 'who created me' concept?"
Ultimately, there is no real overhead to storing (my)self on a new object, I guess, but as I'm developing and testing, I tend to have a whole lot of 'stranded objects' I have to remove manually.
Thoughts?
Thanks! -- Russ Whaley whaley.russ@gmail.com
I have a strong dislike for incompletely initialised objects. So I would do it like this: myInstVar := TheDependentClass newFor: self. (together with any other essential information as parameters). In my Smalltalk system it would look like this: Whatever subclass: #TheDependentClass instanceConstantNames: 'owner' ... class methods for: 'instance creation' newFor: owner ^(self basicNew) pvtOwner: owner; yourself methods for: 'initialising' pvtOwner: anObject super pvtPostNew. owner := anObject. Private access to methods with a 'pvt' prefix is enforced. Instance constants can only be set in private methods. There's an additional wrinkle that makes it a run time error to call TheDependentClass new, so that you cannot get an incompletely initialised object. In any Smalltalk you can follow similar conventions even if they are not enforced. Of course if you don't mind incompletely initialised objects, nothing stops you writing code that allows them. The question is whether you want to be able to trust the 'owner' field or not. On Thu, 18 Jun 2020 at 09:46, Esteban Maringolo <emaringolo@gmail.com> wrote:
Objects interact with each other by sending messages, although you can get the sender by using reflection (thisContext sender), it is not a common practice to do so. So if you need another object to know the sender (or any other object) you simply pass it as a parameter.
So modifying your example, and making the syntax actually work it would be:
self property: ObjectClass new. self property caller: self.
and then when you need to deal with that you can simply get a reference to that object and send it a message to do something: self property caller doSomething.
You can also have something like
self property: (ObjectClass for: self)
In that case the #for: message is received by "ObjectClass class", which you can think of as if it were a Factory or a "static" method (it is not! it is much more powerful than that).
ObjectClass class>>#for: callerObject ^self new setCaller: callerObject; yourself
And that's it, you have an instance of ObjectClass that you initialized by sending #for: instead of #new (internally it ended up calling #new, but from the outside it was just a message send).
And for the most part that's Smalltalk: Objects and messages.
Regards!
Esteban A. Maringolo
On Wed, Jun 17, 2020 at 6:19 PM Russ Whaley <whaley.russ@gmail.com> wrote:
I find myself, over and over, creating a & storing q new object in an
instVar, then storing (my)self on that object - so I can have easy access to the 'object that created me.'
<what I do now...>
self instVar := NewClass new.
self instVar callingObject: self.
"where these call the same messages"
self myMessage.
self instVar callingObject myMessage.
<is there a way to...>
self instVar := NewClass new.
self instVar objectWhoCreatedMe myMessage.
"I know there is a 'thisContext sender' - but is there a 'who created
me' concept?"
Ultimately, there is no real overhead to storing (my)self on a new
object, I guess, but as I'm developing and testing, I tend to have a whole lot of 'stranded objects' I have to remove manually.
Thoughts?
Thanks! -- Russ Whaley whaley.russ@gmail.com
Thank you both for your insights. Iâve done the newFor: style many times, but where it falls short is when I read in a STON object. No worries, I was just wondering if there was something cool like âwhat object am I sitting on?â... I looked through Context and the client message will be helpful to me in other areas. Iâm always eager to learn. Thank you very much for being willing to teach. Thanks! Russ On Wed, Jun 17, 2020 at 9:05 PM Richard O'Keefe <raoknz@gmail.com> wrote:
I have a strong dislike for incompletely initialised objects. So I would do it like this:
myInstVar := TheDependentClass newFor: self.
(together with any other essential information as parameters). In my Smalltalk system it would look like this:
Whatever subclass: #TheDependentClass instanceConstantNames: 'owner' ... class methods for: 'instance creation' newFor: owner ^(self basicNew) pvtOwner: owner; yourself
methods for: 'initialising' pvtOwner: anObject super pvtPostNew. owner := anObject.
Private access to methods with a 'pvt' prefix is enforced. Instance constants can only be set in private methods. There's an additional wrinkle that makes it a run time error to call TheDependentClass new, so that you cannot get an incompletely initialised object.
In any Smalltalk you can follow similar conventions even if they are not enforced.
Of course if you don't mind incompletely initialised objects, nothing stops you writing code that allows them. The question is whether you want to be able to trust the 'owner' field or not.
On Thu, 18 Jun 2020 at 09:46, Esteban Maringolo <emaringolo@gmail.com> wrote:
Objects interact with each other by sending messages, although you can get the sender by using reflection (thisContext sender), it is not a common practice to do so. So if you need another object to know the sender (or any other object) you simply pass it as a parameter.
So modifying your example, and making the syntax actually work it would be:
self property: ObjectClass new. self property caller: self.
and then when you need to deal with that you can simply get a reference to that object and send it a message to do something: self property caller doSomething.
You can also have something like
self property: (ObjectClass for: self)
In that case the #for: message is received by "ObjectClass class", which you can think of as if it were a Factory or a "static" method (it is not! it is much more powerful than that).
ObjectClass class>>#for: callerObject ^self new setCaller: callerObject; yourself
And that's it, you have an instance of ObjectClass that you initialized by sending #for: instead of #new (internally it ended up calling #new, but from the outside it was just a message send).
And for the most part that's Smalltalk: Objects and messages.
Regards!
Esteban A. Maringolo
On Wed, Jun 17, 2020 at 6:19 PM Russ Whaley <whaley.russ@gmail.com> wrote:
I find myself, over and over, creating a & storing q new object in an
instVar, then storing (my)self on that object - so I can have easy access to the 'object that created me.'
<what I do now...>
self instVar := NewClass new.
self instVar callingObject: self.
"where these call the same messages"
self myMessage.
self instVar callingObject myMessage.
<is there a way to...>
self instVar := NewClass new.
self instVar objectWhoCreatedMe myMessage.
"I know there is a 'thisContext sender' - but is there a 'who created
me' concept?"
Ultimately, there is no real overhead to storing (my)self on a new
object, I guess, but as I'm developing and testing, I tend to have a whole lot of 'stranded objects' I have to remove manually.
Thoughts?
Thanks! -- Russ Whaley whaley.russ@gmail.com
-- Russ Whaley whaley.russ@gmail.com
as a general principle do not use thisContext. S.
On 20 Jun 2020, at 01:12, Russ Whaley <whaley.russ@gmail.com> wrote:
Thank you both for your insights. Iâve done the newFor: style many times, but where it falls short is when I read in a STON object. No worries, I was just wondering if there was something cool like âwhat object am I sitting on?â... I looked through Context and the client message will be helpful to me in other areas. Iâm always eager to learn. Thank you very much for being willing to teach.
Thanks! Russ
On Wed, Jun 17, 2020 at 9:05 PM Richard O'Keefe <raoknz@gmail.com <mailto:raoknz@gmail.com>> wrote: I have a strong dislike for incompletely initialised objects. So I would do it like this:
myInstVar := TheDependentClass newFor: self.
(together with any other essential information as parameters). In my Smalltalk system it would look like this:
Whatever subclass: #TheDependentClass instanceConstantNames: 'owner' ... class methods for: 'instance creation' newFor: owner ^(self basicNew) pvtOwner: owner; yourself
methods for: 'initialising' pvtOwner: anObject super pvtPostNew. owner := anObject.
Private access to methods with a 'pvt' prefix is enforced. Instance constants can only be set in private methods. There's an additional wrinkle that makes it a run time error to call TheDependentClass new, so that you cannot get an incompletely initialised object.
In any Smalltalk you can follow similar conventions even if they are not enforced.
Of course if you don't mind incompletely initialised objects, nothing stops you writing code that allows them. The question is whether you want to be able to trust the 'owner' field or not.
On Thu, 18 Jun 2020 at 09:46, Esteban Maringolo <emaringolo@gmail.com <mailto:emaringolo@gmail.com>> wrote: Objects interact with each other by sending messages, although you can get the sender by using reflection (thisContext sender), it is not a common practice to do so. So if you need another object to know the sender (or any other object) you simply pass it as a parameter.
So modifying your example, and making the syntax actually work it would be:
self property: ObjectClass new. self property caller: self.
and then when you need to deal with that you can simply get a reference to that object and send it a message to do something: self property caller doSomething.
You can also have something like
self property: (ObjectClass for: self)
In that case the #for: message is received by "ObjectClass class", which you can think of as if it were a Factory or a "static" method (it is not! it is much more powerful than that).
ObjectClass class>>#for: callerObject ^self new setCaller: callerObject; yourself
And that's it, you have an instance of ObjectClass that you initialized by sending #for: instead of #new (internally it ended up calling #new, but from the outside it was just a message send).
And for the most part that's Smalltalk: Objects and messages.
Regards!
Esteban A. Maringolo
On Wed, Jun 17, 2020 at 6:19 PM Russ Whaley <whaley.russ@gmail.com <mailto:whaley.russ@gmail.com>> wrote:
I find myself, over and over, creating a & storing q new object in an instVar, then storing (my)self on that object - so I can have easy access to the 'object that created me.'
<what I do now...>
self instVar := NewClass new.
self instVar callingObject: self.
"where these call the same messages"
self myMessage.
self instVar callingObject myMessage.
<is there a way to...>
self instVar := NewClass new.
self instVar objectWhoCreatedMe myMessage.
"I know there is a 'thisContext sender' - but is there a 'who created me' concept?"
Ultimately, there is no real overhead to storing (my)self on a new object, I guess, but as I'm developing and testing, I tend to have a whole lot of 'stranded objects' I have to remove manually.
Thoughts?
Thanks! -- Russ Whaley whaley.russ@gmail.com <mailto:whaley.russ@gmail.com>
-- Russ Whaley whaley.russ@gmail.com <mailto:whaley.russ@gmail.com>
Stéphane Ducasse http://stephane.ducasse.free.fr / http://www.pharo.org 03 59 35 87 52 Assistant: Aurore Dalle FAX 03 59 57 78 50 TEL 03 59 35 86 16 S. Ducasse - Inria 40, avenue Halley, Parc Scientifique de la Haute Borne, Bât.A, Park Plaza Villeneuve d'Ascq 59650 France
Why? (question, not a challenge :) ) - I really only use it in a Logger class I developed that letâs me know at the time of logging, what method and class Iâm in - ... write to the log... done. On Sat, Jun 20, 2020 at 3:08 AM Stéphane Ducasse <stephane.ducasse@inria.fr> wrote:
as a general principle do not use thisContext.
S.
On 20 Jun 2020, at 01:12, Russ Whaley <whaley.russ@gmail.com> wrote:
Thank you both for your insights. Iâve done the newFor: style many times, but where it falls short is when I read in a STON object. No worries, I was just wondering if there was something cool like âwhat object am I sitting on?â... I looked through Context and the client message will be helpful to me in other areas. Iâm always eager to learn. Thank you very much for being willing to teach.
Thanks! Russ
On Wed, Jun 17, 2020 at 9:05 PM Richard O'Keefe <raoknz@gmail.com> wrote:
I have a strong dislike for incompletely initialised objects. So I would do it like this:
myInstVar := TheDependentClass newFor: self.
(together with any other essential information as parameters). In my Smalltalk system it would look like this:
Whatever subclass: #TheDependentClass instanceConstantNames: 'owner' ... class methods for: 'instance creation' newFor: owner ^(self basicNew) pvtOwner: owner; yourself
methods for: 'initialising' pvtOwner: anObject super pvtPostNew. owner := anObject.
Private access to methods with a 'pvt' prefix is enforced. Instance constants can only be set in private methods. There's an additional wrinkle that makes it a run time error to call TheDependentClass new, so that you cannot get an incompletely initialised object.
In any Smalltalk you can follow similar conventions even if they are not enforced.
Of course if you don't mind incompletely initialised objects, nothing stops you writing code that allows them. The question is whether you want to be able to trust the 'owner' field or not.
On Thu, 18 Jun 2020 at 09:46, Esteban Maringolo <emaringolo@gmail.com> wrote:
Objects interact with each other by sending messages, although you can get the sender by using reflection (thisContext sender), it is not a common practice to do so. So if you need another object to know the sender (or any other object) you simply pass it as a parameter.
So modifying your example, and making the syntax actually work it would be:
self property: ObjectClass new. self property caller: self.
and then when you need to deal with that you can simply get a reference to that object and send it a message to do something: self property caller doSomething.
You can also have something like
self property: (ObjectClass for: self)
In that case the #for: message is received by "ObjectClass class", which you can think of as if it were a Factory or a "static" method (it is not! it is much more powerful than that).
ObjectClass class>>#for: callerObject ^self new setCaller: callerObject; yourself
And that's it, you have an instance of ObjectClass that you initialized by sending #for: instead of #new (internally it ended up calling #new, but from the outside it was just a message send).
And for the most part that's Smalltalk: Objects and messages.
Regards!
Esteban A. Maringolo
On Wed, Jun 17, 2020 at 6:19 PM Russ Whaley <whaley.russ@gmail.com> wrote:
I find myself, over and over, creating a & storing q new object in an
instVar, then storing (my)self on that object - so I can have easy access to the 'object that created me.'
<what I do now...>
self instVar := NewClass new.
self instVar callingObject: self.
"where these call the same messages"
self myMessage.
self instVar callingObject myMessage.
<is there a way to...>
self instVar := NewClass new.
self instVar objectWhoCreatedMe myMessage.
"I know there is a 'thisContext sender' - but is there a 'who created
me' concept?"
Ultimately, there is no real overhead to storing (my)self on a new
object, I guess, but as I'm developing and testing, I tend to have a whole lot of 'stranded objects' I have to remove manually.
Thoughts?
Thanks! -- Russ Whaley whaley.russ@gmail.com
-- Russ Whaley whaley.russ@gmail.com
-------------------------------------------- Stéphane Ducasse http://stephane.ducasse.free.fr / http://www.pharo.org 03 59 35 87 52 Assistant: Aurore Dalle FAX 03 59 57 78 50 TEL 03 59 35 86 16 S. Ducasse - Inria 40, avenue Halley <https://www.google.com/maps/search/40,+avenue+Halley?entry=gmail&source=g> , Parc Scientifique de la Haute Borne, Bât.A, Park Plaza Villeneuve d'Ascq 59650 France
-- Russ Whaley whaley.russ@gmail.com
On Sun, Jun 21, 2020, 14:54 Russ Whaley <whaley.russ@gmail.com> wrote:
Why? (question, not a challenge :) )
- I really only use it in a Logger class I developed that letâs me know at the time of logging, what method and class Iâm in - ... write to the log... done.
That's a reasonable use. In general, you don't use it to derive meaning that your program relies on. Stack reporting is a good use. Your logging use is a degenerate case of stack reporting.
On Sat, Jun 20, 2020 at 3:08 AM Stéphane Ducasse < stephane.ducasse@inria.fr> wrote:
as a general principle do not use thisContext.
S.
On 20 Jun 2020, at 01:12, Russ Whaley <whaley.russ@gmail.com> wrote:
Thank you both for your insights. Iâve done the newFor: style many times, but where it falls short is when I read in a STON object. No worries, I was just wondering if there was something cool like âwhat object am I sitting on?â... I looked through Context and the client message will be helpful to me in other areas. Iâm always eager to learn. Thank you very much for being willing to teach.
Thanks! Russ
On Wed, Jun 17, 2020 at 9:05 PM Richard O'Keefe <raoknz@gmail.com> wrote:
I have a strong dislike for incompletely initialised objects. So I would do it like this:
myInstVar := TheDependentClass newFor: self.
(together with any other essential information as parameters). In my Smalltalk system it would look like this:
Whatever subclass: #TheDependentClass instanceConstantNames: 'owner' ... class methods for: 'instance creation' newFor: owner ^(self basicNew) pvtOwner: owner; yourself
methods for: 'initialising' pvtOwner: anObject super pvtPostNew. owner := anObject.
Private access to methods with a 'pvt' prefix is enforced. Instance constants can only be set in private methods. There's an additional wrinkle that makes it a run time error to call TheDependentClass new, so that you cannot get an incompletely initialised object.
In any Smalltalk you can follow similar conventions even if they are not enforced.
Of course if you don't mind incompletely initialised objects, nothing stops you writing code that allows them. The question is whether you want to be able to trust the 'owner' field or not.
On Thu, 18 Jun 2020 at 09:46, Esteban Maringolo <emaringolo@gmail.com> wrote:
Objects interact with each other by sending messages, although you can get the sender by using reflection (thisContext sender), it is not a common practice to do so. So if you need another object to know the sender (or any other object) you simply pass it as a parameter.
So modifying your example, and making the syntax actually work it would be:
self property: ObjectClass new. self property caller: self.
and then when you need to deal with that you can simply get a reference to that object and send it a message to do something: self property caller doSomething.
You can also have something like
self property: (ObjectClass for: self)
In that case the #for: message is received by "ObjectClass class", which you can think of as if it were a Factory or a "static" method (it is not! it is much more powerful than that).
ObjectClass class>>#for: callerObject ^self new setCaller: callerObject; yourself
And that's it, you have an instance of ObjectClass that you initialized by sending #for: instead of #new (internally it ended up calling #new, but from the outside it was just a message send).
And for the most part that's Smalltalk: Objects and messages.
Regards!
Esteban A. Maringolo
On Wed, Jun 17, 2020 at 6:19 PM Russ Whaley <whaley.russ@gmail.com> wrote:
I find myself, over and over, creating a & storing q new object in an
instVar, then storing (my)self on that object - so I can have easy access to the 'object that created me.'
<what I do now...>
self instVar := NewClass new.
self instVar callingObject: self.
"where these call the same messages"
self myMessage.
self instVar callingObject myMessage.
<is there a way to...>
self instVar := NewClass new.
self instVar objectWhoCreatedMe myMessage.
"I know there is a 'thisContext sender' - but is there a 'who created
me' concept?"
Ultimately, there is no real overhead to storing (my)self on a new
object, I guess, but as I'm developing and testing, I tend to have a whole lot of 'stranded objects' I have to remove manually.
Thoughts?
Thanks! -- Russ Whaley whaley.russ@gmail.com
-- Russ Whaley whaley.russ@gmail.com
-------------------------------------------- Stéphane Ducasse http://stephane.ducasse.free.fr / http://www.pharo.org 03 59 35 87 52 Assistant: Aurore Dalle FAX 03 59 57 78 50 TEL 03 59 35 86 16 S. Ducasse - Inria 40, avenue Halley <https://www.google.com/maps/search/40,+avenue+Halley?entry=gmail&source=g> , Parc Scientifique de la Haute Borne, Bât.A, Park Plaza Villeneuve d'Ascq 59650 France
-- Russ Whaley whaley.russ@gmail.com
participants (5)
-
Esteban Maringolo -
Richard O'Keefe -
Richard Sargent -
Russ Whaley -
Stéphane Ducasse