How To Clear The Undo/redo History

[yunjun]

Hi, does anybody know how to clear the undo/redo history in the API?

I am writing code to import files which contain maya objects I later create in the Maya scene. Since the import command doesn't need to support undo/redo, I set its isUndoable func to be false. But very soon, I found the problem when I accidentally execute the undo command : Maya skipped my import command (not undoable), and tried to undo the last command executed before I imported my file. It deleted a Maya object in my current scene (the deletion was my last command before importing), which bears the same name as the one in my earlier scene. So I am thinking if I can clear the undo/redo history every time I import a different file. Is this possible?

Thanks!

[yunjun]

just saw a mel command 'flushdUndo' which might help. But is it proper to execute so many mel commands in the api?

[joojaa]

QUOTE(yl2000 @ 08/29/07, 11:00 PM) [snapback]272476[/snapback]
But is it proper to execute so many mel commands in the api?

Api only deals with import export and nodes, not users settings. There shouldnt be any reason as to why youd need to disable undo form the api.

[yunjun]

Thanks for your response. I didn't know that. To me it seems logical to clear the undo list since after importing the scene is totally a different new one. am I missing something?

[daniel-faust]

A file that contains scene data, like the one you want to import, contains nothing but a bunch of mel commands which, while getting executed one after the other, creates the scene.

You could recreate or fake the entire import process by typing one command after another into the script editor.

Since everything you have already done before importing the new file is also nothing but a series of mel commands, the import process is nothing but a continuation of that already executed series of mel commands, and thus there is no reason to flush the history if the user does not want it explicity. You need to be able to undo the import in order to be able to undo what you did before the import process.

Because of this, it does not matter how contextually different the data you're importing is (ie. your scene contains a car and you want to import an apple), the mere action of importing the data defines that they have something in common; in the "worst" case they share only the 3d space. You need to be able to undo all the changes which affect that 3d space in any possible way, and the import process is one them.

[joojaa]

In that case you tie the undo off in the mel command that invokes whatever your api code is doing.