Works about how to embed the expression into MEL script

[david-shower]

Hello,guys.Happy time!!!A script about rigging the caterpillar treads automactically.by far everything goes fine but the procedure can not describe an expression,which is embeded in the script,in the expression editor.now the partion of the script will show you:

$treadExpr = "\"" + "$cater = " + $newName + ".caterpillar;\n" +
                    "if($cater >= 0)\n{\n" + "int $a = 0;\n" +
                    "   for($a = 0;$a < " + $howManyPieces + ";$a++)\n" +
                    "   {\n" +
                    "    string $sampleLocs = `listConnections (" + $NonTitleNode + ".locators" + "[\"$a\"])`;\n" +
                    "    setAttr " + $newNodeName + ".parameter" + " (" + $howManyPieces + "*linstep(0," + $howManyPieces + ",($cater + $a)%" + $howManyPieces + "));\n" +
                    "    float $posVal[] = `getAttr " + $newNodeName + ".position" + "`;\n" +
                    "    $sampleLocs" + ".translateX" + " = $posVal[0];\n" +
                    "    $sampleLocs" + ".translateY" + " = $posVal[1];\n" +
                    "    $sampleLocs" + ".translateZ" + " = $posVal[2];\n" +
                    "   }\n" +
                    "}\n" + "\"";
expression -s $treadExpr -n "treadsAnimExpr" -ae 1 -uc all;

this is  a part. 

I want to rig the treads automatically with it,and use a node called pointOnCurveInfo to finish it.but it gets here,the wrong runs out.

// Error: Attribute not found or variable missing '$':  unknown1.locators[$a] // // Error: $sampleLocs.translateX = $posVal[0]; // // Error: Line 9.23: Syntax error // // Error: $sampleLocs.translateY = $posVal[1]; // // Error: Line 10.23: Syntax error // // Error: $sampleLocs.translateZ = $posVal[2]; // // Error: Line 11.23: Syntax error //  

now I can't deal with it,so can you tell me ,thank you ,looking forward to your answer,thanks a lot. 

[joojaa]

editted your posr so one can read your code.

The "\"" parts are unneccesery

Anyway any expression that contains listConnecyions and setAttr, should be thrown away without questions asked. Nothing good can come out of this expressions, ever. Just use copy incomming graph without expressions its faster and has no side effects. Your expression has a lot of them.

EXPRESSIONS ARE NOT MEL! And they need to obey the dg evaluation rules your expression is breaking them really badly.