Sett Attributes in Expression

[autumn]

Hi!
I'm still somewhat new to expressions and MEL. Please correct me if I'm wrong, but as I understand it, MEL and the expression language are different, so if something will work in one, it won't necissarily work in the other??

What I'm trying to do is make a swich of some sort that will reset my character to it's default neutral pose. To do this I was going to make an boolean attribute and write an expression for it.

What I don't know is what the scripting for changing the value of something in the expression editor, it seems. In the Script Editor:

setAttr "name.channel" #;

works to change attributes, but that very same line won't have any effect in the expression editor. What is the code I need to do this??

I can't just write:
if (my controll == on)
{Object.Attribute=number}

Becuase than the values of my objects that I'm trying to change get frozen and I can't change them anymore at all, which is NOT what I want.

SO!
Can anyone help me with this please??

Am I on the complete wrong path in thinking that an expression is what I need to accomplish this?

[failure]

Expression and mel scripts both use same syntax and same language. Difference is in execution mode. You execute scripts "on demand" while expression execute "automatically" every frame as the animation plays.

Expressions are generally used for procedural animation while scripts are used for various tasks that need to be automated.

What you need is a script, and you need to run it once when you want to reset the character.

There are some minor syntactical differences between expressions and scripts. For convenience you can do this in expression:

object.attribute = value;

while in script you must use setAttr command:

setAttr object.attribute value;

What you normally want to do is define a procedure containing your code and call it as needed. Open a script editor and type:

global proc myTask(){
print( "hello" );
}

Now select it and press ctrl+enter. This will execute the procedure definition. From now on you can call your procedure by typing "myTask" in the command line or script editor.

[autumn]

THANK YOU!!!

That's the exact very thing I was looking for!

I have a few more little questions, if you don't mind.

newbie question, I know Is there a way to save all the procedures I make so that I don't always have to copy them over into the script editor every time?? I though the source script would do, but it doesn't seem to, or else there's something I'm doing incorrectly.

Also, if I define a great number of procedures than forgett the name of one, is there a way I can call them all up to review the coding instead of digging through all the executed commands in the script editor?

Also, when I go 'save selected' from the menubar in the script editor, am I correct in thinking that it is saving only the text that I have selected at the moment and that I would probably use this to import my scripts back into maya?

Thanx again, it's much appreciated.

[failure]

Common approach is following: Every global procedure you define, logicaly represents a new command you upgtrade your system with. You should define a global procedure myTask() and put it in the file with same name: "myTask.mel". This file could contain number of additional non-global "helper" procedures used by myTask but not visible "from the outside".

"myTask.mel" should be placed in one of the maya's script paths. You can get currently defined script paths with:

getenv "MAYA_SCRIPT_PATH"

Now with everything in place, when you try to execute myTask from the script editor maya will first search internal commands database to see if this is "built-in" or "plug-in" command. If not it will search all script path directories to see if there is a mel file named "myTask.mel". If the file is found, maya looks inside if there is a global proc with the same name defined. If yes, it will execute it.

Additionaly you can use whatIs command to check if command is a script and where it's located.

[autumn]

Thanx again! That was an extremely helpfull answer.

[joojaa]

Okay failures eplanation is a bit lacking.

object.attribute = value;

while in script you must use setAttr command:

setAttr object.attribute value;

The object.attribute = value; type is not just syntax sugar it IS linkage, see if you use setAttr object.attribute value; or especialy getAttr object.attribute value; Or any non expression syntx in your script you might be forcing maya to BLINDLY evaluate the expression wich basicaly means it msut be run whenever a change is made. Also because maya does not know what IS linked to what it might not eveluate untill you advance a frame. A linked one will, and it will even optimize dependencies, know if object is renamed etc etc etc.

So only use setattr if you need to set a compoud atribute unsettable in other way or of non linkable type such as string.

ONLY use gatAttr whenever your sure theres absolutely NO other way. Se getattr forces the graph to re evaluate causing maya to solve things unnnecceserily many many many times. Same applys to eval.