• *PROPERTY_DIFFERENCE Function
• *summary_groups_enum Function
• *variable_delegate Function
• *variable_name_normalize Function
• *variable_parent_restore Function
• *variable_parent_set Function
• *variable_to_script Function
• a5_cnvrt_dot_vars Function
• a5_copy_ask_vars Function
• a5_defaultvalue_get Function
• a5_defaultvalue_set Function
• A5_DEFINE_GLOBAL_VARS Function
• A5_DELETE_SETTINGS Function
• a5_dim_ask_vars Function
• A5_EXPORT_PROPS_TO_CMDS Function
• a5_extract_ask_vars Function
• a5_get_var_names Function
• a5_is_var_name_valid Function
• a5_javascript_property_to_attribute Function
• a5_list_user_vars Function
• A5_LOAD_SETTINGS Function
• a5_prompt_for_ask_vars Function
• a5_property_to_arguments Function
• a5_property_to_attribute Function
• A5_SAVE_SETTINGS Function
• a5w_resolvevariablesinoverridesettings Function
• all_variables Function
• CANCEL Function
• getenvironmentvariable Function
• GLOBAL_VARIABLES Function
• LOCAL_VARIABLES Function
• Merge_Variable_Frames Function
• PROP_VALID Function
• PROPERTIES_ENUM Function
• PROPERTY_FROM_STRING Function
• PROPERTY_RECURSE_ASSIGN Function
• PROPERTY_TO_STRING Function
• propertyfromquerystring Function
• REPLACE_VARIABLES_IN_STRING Function
• SESSION_VARIABLES Function
• SHOWVAR Function
• submit_let Function
• variable_exists Function
• variable_name_normalize Function

CANCEL Function

Syntax

Arguments

No_Error

Optional. Default = .T. Whether to suppress error messages. .T. = Suppress Alpha Anywhere error messages. .F. = Display error messages.

Description

Cause script to cancel the calling operation (if supported by Trigger).

Discussion

The CANCEL() command sets the Alpha Anywhere system variable A_CAN_DO to "NO". All of the events whose names are prefixed with "Can" can be canceled, thus preventing the event from occurring. The CANCEL() command is used to cancel an event. The CANCEL() command can take an optional flag which can be .T. or .F. If the flag is set to .T. then Alpha Anywhere error messages are suppressed. When you cancel an event, if your Xbasic code provides the appropriate feedback to the end-user as to why the event is being canceled (for example, by including a UI_MSG_BOX()in the code), then you would not want additional error reporting from Alpha Anywhere itself. In this case, you would use CANCEL(.T.) in your code to cancel the event.

Example

For example, assume that you have a control on a form and that you define a script for that control's CanDepart event. Assume that the control has focus and that the user tries to give focus to another control on the form. This will cause the control's CanDepart event to fire. If this script executes the CANCEL() command, the event will be canceled and the user will not be able to move focus away from this control. The following example shows how a script could be attached to a table's CanDeleteRecord event. When the user deletes a record, the script is executed. It displays a dialog box asking the user for the password. If he enters the correct password, the record is deleted. Otherwise, the Delete event is canceled and the record is retained. This script prompts the user for a password before deleting a record.

password = "Alpha5"
user = UI_GET_text("Password", "Enter the password", "******", "&&&&&&")
if (user = "") then
    end
end if
if (.not.(user == password)) then
    cancel()
    ui_msg_box("Password", "Password invalid.")
end if

A Solution for Required Fields

This script is attached to a form's CanSave event and checks the values of three required fields: field1, field2, and field3.

if isNULL(field1) .or isNULL(field2) .or. isNULL(field3) then
    cancel()
end if

Limitations

Desktop applications only.

See Also

• Canceling Events
• UI_MSG_BOX()