Form Init, Initialized, writing event handlers in D365fo

/// <summary>
/// This class is used to handle the event on SalesTable form
/// </summary>
public static class SM_Sales_SalesTableForm_Extension
{    
    /// <summary>
    ///
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    [FormDataSourceEventHandler(formDataSourceStr(SalesTable, SM_SalesTable), FormDataSourceEventType::Writing)]
    public static void SM_SalesTable_OnWriting(FormDataSource sender, FormDataSourceEventArgs e)
    {   
        FormDataSource      fdsSalesTable = sender.formRun().dataSource("SalesTable");
        SalesTable           salesTable = fdsSalesTable.cursor();

        FormDataSource      fdsSMSalesTable = sender.formRun().dataSource("SM_SalesTable");
        SM_SalesTable           smSalesTable = fdsSMSalesTable.cursor();       

        if(!smSalesTable.SalesTable)
        {
            smSalesTable.SalesTable = salesTable.RecId;
        }
        
    }

    /// <summary>
    ///
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    [FormDataSourceEventHandler(formDataSourceStr(SalesTable, SM_SalesLine), FormDataSourceEventType::Writing)]
    public static void SM_SalesLine_OnWriting(FormDataSource sender, FormDataSourceEventArgs e)
    {
        FormDataSource      fdsSalesLine = sender.formRun().dataSource("SalesLine");
        SalesLine           salesLine = fdsSalesLine.cursor();

        FormDataSource      fdsSMSalesLine = sender.formRun().dataSource("SM_SalesLine");
        SM_SalesLine          smSalesLine = fdsSMSalesLine.cursor();

        if(!smSalesLine.SalesLine)
        {
            smSalesLine.SalesLine = salesLine.RecId;
        }
        
    }

    /// <summary>
    ///
    /// </summary>
    /// <param name="sender"></param>
    /// <param name="e"></param>
    [FormEventHandler(formStr(SalesTable), FormEventType::Initialized)]
    public static void SalesTable_OnInitialized(xFormRun sender, FormEventArgs e)
    {
        CustParameters custParameters   = CustParameters::find();
        FormDataSource SM_SalesTable_ds = sender.dataSource(formDataSourceStr(SalesTable, SM_SalesTable));
        FormDataSource SM_SalesLine_ds  = sender.dataSource(formDataSourceStr(SalesTable, SM_SalesLine));

        SM_SalesTable_ds.object(fieldNum(SM_SalesTable, CumulativeGrossWeight)).visible(custParameters.SM_ActivateSOGrossWeightCalculation);
        SM_SalesLine_ds.object(fieldNum(SM_SalesLine, GrossWeight)).visible(custParameters.SM_ActivateSOGrossWeightCalculation);
        sender.control(sender.controlId(formControlStr(SalesTable, SM_SalesCalculateCumulativeGrossWeight))).visible(custParameters.SM_ActivateSOGrossWeightCalculation);

    }

}

class LogisticsPostalAddressGrid_Eventhandler
{
    /// <summary>
    ///
    /// </summary>
    /// <param name="args"></param>
    [PostHandlerFor(formStr(LogisticsPostalAddressGrid), formMethodStr(LogisticsPostalAddressGrid, init))]
    public static void LogisticsPostalAddressGrid_Post_init(XppPrePostArgs args)
    {
        FormRun             element       = Args.getThis(); //form element
        FormControl         myNewButton   = element.design(0).controlName("MapButton");

        myNewButton.visible(false);
    }

}