Self-interest July 2005

self-interest@lists.selflanguage.org

4 participants
5 discussions

Adding method slots dynamically
by oscar_lopez_p 16 Aug '05

16 Aug '05

Hello, How can I add dynamically a method slot to a self object? . I have: the method selector, the argument names and the body (source code) of a method, and I need (at runtime) to create a method from them and add it to an existing object. Thanks for the help, Oscar Lopez

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Re: [self-interest] mirrors (second try)
by Reinout Heeck 12 Jul '05

12 Jul '05

Jecel Assumpcao Jr wrote: > > [...] the idea of using > different viewpoints instead of mirrors as suggested for Us. > This sounds like something I need to know/understand but I completely fail to comprehend what it references. What is meant by 'viewpoints' and 'Us', are we talking about a design pattern here? Reinout -------

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mirrors (second try)
by Jecel Assumpcao Jr 09 Jul '05

09 Jul '05

Sorry - my email program messed up my first attempt to send this. Reinout Heek wrote in the comp.lang.smalltalk newsgroup: > I came across this paper recently that tries to identify and address > some problems with the Smalltalk MOP: > > Gilad Bracha and David Ungar. Mirrors: Design Principles for Meta-level > Facilities of Object-Oriented Programming Languages. In Proc. of the > ACM Conf. on Object-Oriented Programming, Systems, Languages and > Applications, October 2004. > > http://bracha.org/mirrors.pdf (14 pages) > > Enjoy! > > Reinout > ------- Perhaps other people in this list will find this paper interesting. I really liked it though I wished they had mentioned the idea of using different viewpoints instead of mirrors as suggested for Us. -- Jecel

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None
by None 09 Jul '05

09 Jul '05

> gilad bracha and david ungar. mirrors: Design Principles for Meta-level > http: //bracha.org/mirrors.pdf (14 pages) X-Originating-IP: 67.15.94.35 X-eGroups-Msg-Info: 2:12:4 From: Jecel Assumpcao Jr <jecel(a)merlintec.com> Subject: mirrors X-Yahoo-Group-Post: member; u=20733450; y=sFuyzdQgJUaxn6PbDg19Za1rzvEfeVxXRYomVD5PDI949Q X-Yahoo-Profile: jeceljr Perhaps other people in this list will find this paper interesting. I really liked it though I wished they had mentioned the idea of using different viewpoints instead of mirrors as suggested for Us. -- Jecel

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(fwd) Fw: Self question: interception of assignments
by Jecel Assumpcao Jr 09 Jul '05

09 Jul '05

Here is a reply to an email I received that I thought someone in the list might have a better solution to than mine. -- Jecel ----- Original Message ----- From: "Jecel Assumpcao Jr" To: "Ellen Van Paesschen" Sent: Wednesday, July 06, 2005 5:10 PM Subject: Re: Self question: interception of assignments > Ellen, > > I am forwarding this to the self-interest mailing list so that more people > can look at your problem and perhaps come up with a better solution. > >> can you help me out with this: how can I intercept assignments in Self; >> say every time an assignment is performed I want to trigger another >> action. > > The normal way it has been done in Self is to hide the real data and > assignment slots with a name like rawSomething and then use a regular > method to add your action before or after the assignment. You probably > have seen things like > > ( | rawSalary <- 0. > salary = (rawGrade). > salary: v = (rawGrade: v. updateStatistics). > | ) > >> Since these method slots contain the assign primitive I tried wrapping >> assignments dynamically but I am stuck due to the nr of arguments >> problem.. >> >> wrap: sel = ( | m. new. old. sel2 | >> m:(reflect: self). >> >> old: ((m at: sel) correspondingAssignmentSlot). "here is now the <- >> slot" >> sel2: (old storedName). "the original assign selector" > > Please note the word "corresponding". The way Self is implemented the > assignment slot must have the same name as the data slot with ':' added to > it. A lot of things will stop working if you break this assumption. > >> m at: 'tempy:' PutContents: (reflect: old). "error since wrong nr of >> arguments" > > If old is a slot then (reflect: old) is a mirror on the slot and not on > the actual method. Such an object can only be placed on a data slot which > takes zero arguments. This might be the cause of the error you are seeing. > > In theory you could do "old value" instead (if it were a regular method), > but in this case that will just get you a mirror on the string '<-' which > doesn't help at all. > >> new: ('| :arg1 | triggerAction . tempy: arg1') parseObjectBody. >> >> m at: sel2 PutContents: new. >> ) >> Can I avoid this or is there a more simple way to intercept assignments? > > The most recent version of Self (4.2.1) allows you to store method objects > in slots, but that is enabled by default and I don't see a simple way in > which that would help with your problem. I think the only way to do it is > patching the object like you are doing. You might want to check out the > method 'changeSlotInObjectTo:' in "traits slots plain" or something > similar to rename the original slots adding 'raw' to their names and then > creating two additional methods. > > You might find a related discussion from 1994 interesting: > > http://www.merlintec.com/old-self-interest/msg00520.html > > -- Jecel Here was the reply: thanks for the response - I didn't find a straightforward solution and since we were limited by a paper deadline, I implemented some kind of assignment "shadowing". A new child object is created that overrides the assignment with some action to be triggered and then a resend to the original assignment. All references to the object containing the original assignment are then set to the new child object..

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Self-interest July 2005