[gme-users] Creating read-only attributes in a meta-model

[Cinthya Lopez]

Hi Kevin,

For #1, the third parameter that is passed into ObjectEvent is of type object. When I look at it in the debugger its value is null so casting it to object[] shows null as well. Am I missing something? I am working with GME 14.

I think this would be the information I need. If I can get the “attibuteName” to check which attribute is being modified, I can avoid falling into the case where my add-on code executes again when I modify my “read-only” attribute on the same object.

Thanks,
Cinthya

From: gme-users [mailto:gme-users-bounces at list.isis.vanderbilt.edu] On Behalf Of Kevin Smyth
Sent: Thursday, February 1, 2018 8:58 AM
To: A list for GME users to share thoughts and discuss bugs and fixes. <gme-users at list.isis.vanderbilt.edu>
Subject: [External] Re: [gme-users] Creating read-only attributes in a meta-model

Hi Cinthya,

It is not possible to disable editing of an attribute through the GUI. You can only hide attributes from the GUI.


I'd suggest:
1. Your add-on detects when the user modifies the attribute and sets the value back to the original value. When your addon receives OBJEVENT_ATTR in ObjectEvent, the third parameter contains the old value. For C#, cast it to object[], and you'll see {"ATTR:", "attributeName", "oldValue"}. Or
2. Look at OBJEVENT_ATTR and return E_MGA_CONSTRAINT_VIOLATION to signify the GME transaction should be aborted. In C#, you can do this like
int E_MGA_CONSTRAINT_VIOLATION = 0x87657fff;
throw new COMException("Constraint violation", E_MGA_CONSTRAINT_VIOLATION );
3. Create a hidden attribute in your meta-model. Your add-on sets this attribute and your original attribute to the same value. Then write a constraint that the attributes must be equal

Kevin

On Wed, Jan 31, 2018 at 5:22 PM, Cinthya Lopez <Cinthya_K_Lopez at raytheon.com<mailto:Cinthya_K_Lopez at raytheon.com>> wrote:
Hello,

I am looking for a way to create a read-only attribute in my meta-model. Basically I want to be able to populate the value of my attribute through my add-on and it will only be informational to the user when they create their model.

Does anyone know of a way to do this in GME?

Thank you,
Cinthya

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