On 25/09/2025 00:16, Michael Rans wrote:
"I'd like to learn more about these ObjectiveC containers, though. Can
they be nesting? Can I programatically inquire on them like how many
objects, etc...
OK, I used 'container' in an abstract sense ... while every object can
be seen as a container (because it stores state information which the
-description method might provide for print-object to display) I really
meant objects which happen to encapsulate large amounts of data.
That might be objects of class NSString ... containing text. In a book
database application this could, for instance, be just the title of a
book 'War and Peace' or could be the entire text of the book!
Or it could be a collection class such as NSArray ... containing an
ordered collection of objects ... perhaps the 22 chapter titles in a
book, or perhaps the 10,000 l;ines of text.
So while printing the description of an object is often very useful, it
has the potential to produce far too much text for a neatly formatted
debug display. I would therefor suggest that SDeer should output
minimal information by default, with an option to print the full object
description in a popup window (eg if the user clicks on the minimal
description).
While many/most classes implement -description to produce human
readabl;e statre information, the default implementation of -description
returns an NSString containing a minimal description (class name and
address of the object) similar to this C code:
printf("<%s: %p>", class_getName(object), (void*)object);
eg. for an instance of MyClass it might print <MyClass: 0x00001234>
>> Can they be nesting
Collections may be nested, YES.
>>> Can I programatically inquire on them like how many objects, etc...
Yes and no; there are methods to do that. Collections generally provide
a -count method, string and binary data objects provide a -length
method, but different classes have different behaviors and there's no
general way to know in advance how big the -description of a particular
object will be.
Basically, maybe there's a way I can write my own version of
"print-object" that is more flexible..."
Certainly the object introspection features of the objc runtime allow
you to do that, but trying to cope with all possibilities is an endless
task, which is why I suggest starting with just the class and address
along with an easy wayto print-object the description to somewhere that
copes well if the amount of data returned is large.
The above questions are from the author of Seer who is adding
Objective-C support to his Seer gdb debugger frontend. I am also
interested to learn more on this.
Here is a screenshot of Seer debugging Objective-C:
Inline image
The ticket where Objective-C support is discussed is here:
https://github.com/epasveer/seer
Thanks,
Mike
