Forms extension: Register override lookup method on datasource field using Overrides class

on

Coc class of the form 

/// <summary>
///  	Extension of the <c>FormName</c> form
/// </summary>
[ExtensionOf(formStr(FormName))]
final class FormName_Extension
{
    public void init()
    {
        next init();

        FormNameOverrides overrides = FormNameOverrides ::construct();

        DatasourceName_ds.object(fieldNum(TableName, FieldName))     
            .registerOverrideMethod(methodStr(FormDataObject, lookup),  methodStr(FormNameOverrides, lookupItemId), overrides);
    }
}

Overrides class 

/// <summary>
///     Overrides class for <c>FormName</c> form.
/// </summary>
internal final class FormNameOverrides
{
    public void lookupItemId(FormStringControl _formControl)
    {
        // Get record from form
	InventTable inventTable = _formControl.formRun().dataSource(formDataSourceStr(FormName, DSName)).cursor();
		
        InventTable::lookupItem(_formControl, false);
    }

    public static FormNameOverrides construct()
    {
        return new FormNameOverrides();
    }

    /// <summary>
    ///     Use static constructor instead.
    /// </summary>
    protected void new()
    {
    }
}