| Re: use of 'obj_new' within another object definition [message #32958 is a reply to message #32946] |
Mon, 18 November 2002 15:03   |
Randall Skelton
Messages: 169
Registered: October 2000
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Senior Member |
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Hi Paul,
I think you might have cut a little too much 'object definition stuff'
from your example... in any case, if I understand what you are trying to
do, then try the code examples below.
IDL> a = obj_new('other_object')
% Compiled module: OTHER_OBJECT__DEFINE.
i am here!
IDL> b = obj_new('my_object')
% Compiled module: MY_OBJECT__DEFINE.
i am here!
IDL> help, /heap
Heap Variables:
# Pointer: 0
# Object : 3
<ObjHeapVar1> STRUCT = -> OTHER_OBJECT Array[1]
<ObjHeapVar2> STRUCT = -> MY_OBJECT Array[1]
<ObjHeapVar3> STRUCT = -> OTHER_OBJECT Array[1]
IDL> obj_destroy, a
IDL> obj_destroy, b
IDL> help, /heap
Heap Variables:
# Pointer: 0
# Object : 0
;-----------------------------
pro my_object::cleanup
if obj_valid(self.foo) then obj_destroy, self.foo
; NB: don't try and shortcut the life-cycle by calling
; self.foo->cleanup directly...
end
function my_object::init
self.foo = obj_new('other_object')
return, 1
end
pro my_object__define
s = { my_object, foo: obj_new() }
end
;-----------------------------
EXAMPLE ONE: Use obj_new()
^^^^^^^^^^^^
;-----------------------------
pro other_object::cleanup
; nothing to do here yet
end
function other_object::init
print, ' i am here!'
return, 1
end
pro other_object__define
s = { other_object, a: 0 }
end
;-----------------------------
EXAMPLE TWO: Use ptr_new()
^^^^^^^^^^^^
;-----------------------------
;my_object__define.pro
pro my_object::cleanup
if ptr_valid(self.foo) then begin
obj_destroy, *self.foo
ptr_free, self.foo
endif
end
function my_object::init
self.foo =
ptr_new(obj_new('other_object'))
return, 1
end
pro my_object__define
s = { my_object, foo: ptr_new() }
end
;-----------------------------
On 18 Nov 2002, paul wrote:
> Hi,
> I am experiencing a problem in IDL 5.4.
>
> I create an object called 'my_object', and define it in a file called
> 'my_object__define.pro'
>
> I do the same thing with 'other_object' , and
> 'other_object__define.pro'.
>
> Both of these objects compile and i can create variables with them.
> They both have 'init' functions that do basic initilization stuff.
>
> I know that the 'init' functions are getting called because I can
> put...
>
> print,'i am here ...'
>
> ...statements in the init functions, and I will see the output when
> i initialize an object of that type.
>
> ...
>
>
> Now, my problem is that if I want 'my_object' to have an instance of
> 'other_object' as a member object, the init function( of
> 'other_object')
> doesn't get called.
>
> To eleborate...(snipping irrelevant stuff)
>
> ;----------------------------------
> ;my_object__define.pro
>
> pro my_object__define
>
> foo: obj_new('other_object')
>
> end ; my_object
>
>
> ;------------------------------
> ;other_object__define.pro
>
> function other_object::init
> print, ' i am here!'
> return, 1
> end ; init
>
> pro other_object__define
>
> ;object definition stuff here
>
> end ; other_object
> ;----------------------------
>
>
> When type ' x = obj_new('other_object') ' on the
> command line, I see the ' i am here!'.
>
> When type ' y = obj_new('my_object') ' on the
> command line, I DON"T see the ' i am here!'.
>
> Why is this?
>
> I don't get any errors otherwise, and
> according to the documentation on 'obj_new'
> it seems it should call the 'init' function
> in BOTH circumstances.
>
> Any ideas greatly appreciated,
>
> Paul Wisehart
> wisehart@runbox.com
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