You can change the method name if you don't like it. Generally, you'll never
need to learn about >>asOop unless you work on the VM.

Gulik.

On Wed, Aug 19, 2009 at 4:47 PM, Ronald Spengler <ron.spengler at gmail.com>wrote:

> On second thought, that seems weird. Maybe this is just a C background
> talking, but why call a thing 'pointer' without being able to dereference
> it?
>  - Silly Ron, the Newbie
>
> On Tue, Aug 18, 2009 at 9:41 PM, Ronald Spengler <ron.spengler at gmail.com>wrote:
>
>> Familiar with hashes. Grok it; I can use it to see if two objects are the
>> same object or not, and looking for a particular object by it's hash is
>> probably expensive.
>> Thank you:)
>>
>>
>> On Tue, Aug 18, 2009 at 9:38 PM, Michael van der Gulik <mikevdg at gmail.com
>> > wrote:
>>
>>>
>>>
>>> On Wed, Aug 19, 2009 at 4:19 PM, Ronald Spengler <ron.spengler at gmail.com
>>> > wrote:
>>>
>>>> When I (for example,) in a workspace, Command-P the text 'morph3874
>>>> color: Color red' and see 'aMorph(2413)', what does the number mean? I'm
>>>> guessing it's some kind of object pointer. An OOP perhaps, I've heard people
>>>> speak of those? This has been bugging me for a year, and I can't seem to
>>>> construct a Google string that finds me an answer to the question. Can I use
>>>> that number to find the object in the object memory?
>>>> Why I ask:
>>>>
>>>> I'm presently trying to understand...
>>>>
>>>> http://bugs.squeak.org/bug_view_page.php?bug_id=456
>>>>
>>>>
>>> Look at the code in Morph>>printOn:
>>>
>>> Morph>>printOn: aStream
>>>     | aName |
>>>     super printOn: aStream.
>>>     (aName := self knownName) notNil
>>>         ifTrue: [aStream nextPutAll: '<' , aName , '>'].
>>>     aStream nextPutAll: '('.
>>>     aStream
>>>         print: self identityHash;
>>>         nextPutAll: ')'
>>>
>>> This gets called when you do alt-p on a morph in a workspace. The
>>> second-to-last line is of interest; this is the number that you're seeing.
>>> It's an "identityHash". I'm not going to explain hashing here; Wikipedia can
>>> teach you more if you're curious.
>>>
>>> If you look at the implementation of ProtoObject>>identityHash, it is
>>> primitive 75. If you look at the implementation of Object>>asOop, it is also
>>> primitive 75. So, coincidentally, yes, it is an OOP (object pointer).
>>>
>>> The intention however was just to print out a number that is unique for
>>> each different instance so that you can see whether two variables are
>>> pointing to the same morph. This is useful for debugging. In my own images,
>>> I often modify printOn: methods to print out hashes or oops for the same
>>> reason.
>>>
>>> I'm not sure how you'd convert an oop to an object. I guess you could
>>> search through all objects in the image looking for the right one.
>>>
>>> Gulik.
>>>
>>> --
>>> http://gulik.pbwiki.com/
>>>
>>>
>>>
>>>
>>
>
>
>
>


-- 
http://gulik.pbwiki.com/
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