## CustomOperator.AlwaysEvaluate

### Introduced

v4.0

### Description

Returns or sets whether the custom operator is always evaluated on each request for data as a Boolean (true to always evaluate). This property is off by default, which means that Softimage will not consider the custom operator as needing a new evaluation unless the operator's input or parameters change. However this optimization is not suitable for some simulation-style operators, in which case this property should be set to true.
Note: Because of the "lazy-evaluation" pull model of Softimage this property does not guarantee that the operator will actual evaluate at each frame - it is still necessary for the UI, a script, rendering or some dependent object to request the operator's output.
The recommended callback for setting this property in a Self-Installed Custom Operator is in the _Define callback.
Note: You can read this property from within the update function of a custom operator but setting this property is blocked.

### C# Syntax

    // get accessor
    Boolean rtn = CustomOperator.AlwaysEvaluate;
    // set accessor
    CustomOperator.AlwaysEvaluate = Boolean;

### Examples

#### JScript Example

    NewScene( null, false );
    var null1 = GetPrim("null");
    SetExpr( null1.posx, "10");
    var sop = null1.posx.AddScriptedOp( MyExpr_Update.toString(), null,"MyExpr", "JScript" );
    SetValue( "PlayControl.Current", 3, null );
    sop.AlwaysEvaluate = true;
    val = GetValue( "null.kine.local.posx" );
    Application.LogMessage( val );
    SetValue( "PlayControl.Current", 4, null );
    val = GetValue( "null.kine.local.posx" );
    Application.LogMessage( val );
    // Force scene to reevaluate
    sop.AlwaysEvaluate = false;
    Refresh();
    SetValue( "PlayControl.Current", 5, null );
    val = GetValue( "null.kine.local.posx" );
    Application.LogMessage( val );
    // Scripted operator's update function
    function MyExpr_Update(ctx,out)
    {
            Application.LogMessage( "MyExpr_Update: " + out.name );
            out.Value = ctx.CurrentFrame;
    }
    // Expected results:
    //INFO : MyExpr_Update: Outposx
    //INFO : 3
    //INFO : MyExpr_Update: Outposx
    //INFO : 4
    //INFO : MyExpr_Update: Outposx
    //INFO : 4