A Few Fundamental MEL Commands Everyone Should Know

Here are a couple of useful MEL commands/operators that you'll end up using in a lot of the stuff you write.

continue ;
Skips one iteration of a loop.

break ;
Stops the loop and continues script where the loop ends.

Warning("You messed up, but it isn't too bad so I'll keep going.") ;
Warnings alert the user that something is awry, but it's not a deal breaker.

Error("You messed up bad, I need to quit now.") ;
The error command will stop a script in it's tracks, ending everything.

return ;
Ends a procedure/function/method, but not the entire script. Continues on where the procedure ends. Can also be used to return a value (return $myString).

CGSutra has a great article going into more depth on these and a lot more of the fundamental MEL concepts. Check it out here.

MEL: Trick To Pass An Array Into A String Argument

I wrote a quick proc this morning that will let me pass an array (specified index) into a string argument since Maya won't let you do it any way by default in MEL.

Example...

// Looking For This Object's Shape Node
string $object = "myObject" ;
string $shapeArr[] = `listRelatives -shape $object` ;
string $shapeNode = $shapeArr[0] ;

// The above returns an array, which is annoying.  To me at least...

I'm aware you can use $shapeArr[0] as your shape node without redeclaring it into the second variable, but I've always felt it was sloppy to do it that way.

Here's a simple MEL procedure that makes it easier.

// **********************************************************
// Returns An Index From A String Array
global proc string jgArrToStr (string $array[], int $index) {

     // Get Index From Array
     string $obj = $array[$index] ;
 
     // Return
     return $obj ;
 
}

// Now you can do...

string $object = "myObject" ;
string $shape = jgArrToStr(`listRelatives -shape $object`, 0) ;

This will only work if you know the index you're looking for in the array, but a lot of times MEL returns string arrays when it doesn't need to and you know what it will be.