Calling the contents of an identifier

[compsystems]

In CAS MODE, does not work, evaluates the USER variables, (A, ... Z, L0-L9, M0-M9, etc.) I keep insisting that the quotation marks should be not evaluated the expression.

//CAS MODE with X uppercase
X:=0;
symbExpr:='X+1';
var:="FF1";
CAS( EVAL ( var + "(X):=" + symbExpr ) ); // FF1(X):=1
FF1(2); // RETURNS 1 evaluates X =(

//HOME MODE with X uppercase
X:=0;
symbExpr:='X+1';
var:="FF1";
CAS( EVAL (var + "(X):=" + symbExpr )); // FF1(X):='X+1'
FF1(2); // RETURNS 3 OK

//CAS MODE with x lowercase
purge(x);
symbExpr:='x+1'; // or symbExpr:=x+1;
var:="FF2";
CAS( EVAL ( var + "(x):=" + symbExpr ) ); // FF2(x):='x+1'
FF2(2); // RETURNS 3 OK

At least I was able to execute INPUT CMD from a CAS PRG
run PRGCAS();

PHP Code:

export resetFunctionAppVars( varApp_str )
BEGIN
  expr( "Function." + varApp_str + ":=0"); // "" = "No definition in Symbolic view"
  return "Done";
END;


#cas
  PRGCAS():= 
  BEGIN
    SetFunctionAppVars( "F1" );
    SetFunctionAppVars( "F2" );
    // ....
    return("Done");
  END;
#end

export SetFunctionAppVars( varApp_str )
BEGIN
  local symbExpr, resetVALUE_FX, initVALUE_FX;
  IFERR
    initVALUE_FX := EXPR( varApp_str );
  THEN
    initVALUE_FX := 0; 
  END; 
  resetVALUE_FX := 'X^2/9';
  local ObjectType_SymbolicExpression := 8;
  if 
  (
    input( 
    { { symbExpr, [ ObjectType_SymbolicExpression ] } }, 
    "Set Function App Vars",
    varApp_str+"(X):",
    "Enter Symbolic Expression for "+varApp_str+"(X)",
    resetVALUE_FX, 
    initVALUE_FX
    )
  )
  then
    expr("Function." + varApp_str + ":='" + symbExpr + "'");
    //CAS( EVAL(varApp_str + "(X):=" + symbExpr) );
    //return( { varApp_str, symbExpr, varApp_str + "(X):=" + symbExpr,  varApp_str + ":='" + symbExpr + "'" });
  end;
END;