| Re: object argument passing behaviour changed in v8.2.2? [message #86260 is a reply to message #84593] |
Tue, 22 October 2013 05:16   |
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Paul Van Delst[1]
Messages: 1157
Registered: April 2002
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Senior Member |
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Hi Chris,
Your test code works fine for me. But I changed it to more closely
approximate what I am doing (and added more output of the properties).
The important change is that the procedure in question has been changed
to a method.
-----%<-----
pro IDLitComponent::test_pass_objelement, obj
obj = obj_new('IDLitComponent')
self->GetProperty, name=name
obj->SetProperty, NAME=name ; Set the name...
obj->GetProperty, NAME=name ; ...get it...
print, "In method. Name = ", name ; ...and print
end
pro test_pass
o = objarr(5)
for i=0,4 do begin
scalarobj = obj_new('IDLitComponent',name='scalar work obj')
o[i] = obj_new('IDLitComponent',name='empty rank-1')
scalarobj->test_pass_objelement, o[i]
o[i]->getproperty, name = name ; Get the name...
print, "In caller. Name = ", name ; ...and print
print
endfor
end
-----%<-----
When I run "test_pass" I get the following output:
IDL> test_pass
% Compiled module: TEST_PASS.
In method. Name = scalar work obj
In caller. Name = empty rank-1
In method. Name = scalar work obj
In caller. Name = empty rank-1
In method. Name = scalar work obj
In caller. Name = empty rank-1
In method. Name = scalar work obj
In caller. Name = empty rank-1
In method. Name = scalar work obj
In caller. Name = empty rank-1
So, while the *passed* object is valid upon return, all of the changes
made to it in the method didn't "take".
This is only a problem when the object is an argument to one of its own
methods, but invoked via a different object (in this case "scalarobj").
When the object is passed as an argument to a "regular" procedure (as in
your test case) everything works as expected.
Any ideas? The actual code in question (my operational equivalent of the
main "test_pass") has existed since 2011 - and it's been used to process
data for several satellite sensors.
cheers,
paulv
On 10/21/2013 07:07 PM, Chris Torrence wrote:
> Hi Paul,
>
> Nothing has changed with the way IDL passes objects. However, I'm a
> little confused by your code. When you say that the
> "compute_interpolation_frequency" procedure "allocates the resulting
> object", do you really mean that it just fills in some properties on
> that object? Because it looks like you are doing an obj_new on those
> objects before passing them in.
>
> It looks like something strange is going on with garbage collection,
> where it is somehow freeing up your object inside
> compute_interpolation_frequency. However, I can't imagine why this
> would be happening. I just create a test program which approximates
> what you are doing:
>
> pro test_pass_objelement, obj obj->getproperty, name = name
> obj->SetProperty, NAME='NewName' end o = objarr(5) for i=0,4 do
> begin o[i] = obj_new('IDLitComponent', NAME=STRTRIM(i,2))
> test_pass_objelement, o[i] print, obj_valid(o[i]) endfor end
>
> When I run this code (at least in IDL 8.3), the objects are all valid
> after the procedure call. Can you try running this code to make sure
> it passes for you? If it does, then maybe you can post the details of
> your compute_interpolation_frequency procedure, so we can diagnose
> what is happening inside.
>
> Thanks! -Chris ExelisVIS
>
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