ACTION statement

The ACTION statement creates an action.

Syntax

name [caption] [(param1, ..., paramN)] { actionBody } [options]
name [caption] [(param1, ..., paramN)] contextIndependentOperator [options];

Description

The ACTION statement declares a new action and adds it to the current module.

The statement has two forms: the first form creates an action using the {...} operator, a context-dependent action operator that runs a sequence of inner actions, the second form creates a context-independent one. In the first form the closing brace already ends the statement, so the trailing semicolon is not required (an extra one is allowed by the empty statement rule).

Also, when declaring an action, a set of its options can be specified.

Parameters

• name

  Action name. Simple ID.

• caption

  Action caption. String literal. If no caption is defined, the action name will be its caption.

• param1, ..., paramN

  List of parameters. Each of them is defined by a typed parameter. The list may be empty. These parameters can be later used in the action operator describing the action being created (as well as in some options).

  If parameters are not defined explicitly, they will be automatically calculated when the operator is processed. The order of the parameters will match the order of their appearance in the operator. It is recommended to explicitly define action parameters. This will help find typos and other errors in the declaration (for example, a mismatch of the number of defined parameters with the number of parameters of the created action).

• actionBody

  Body of the {...} operator: a sequence of action operators and, where needed, LOCAL declarations. The body may be empty. The parameters defined in this statement (if any) can be used inside actionBody.

• contextIndependentOperator

  A context-independent action operator describing and creating an action.

• options

  Action options.

Examples

// action declared with the {...} operator; the trailing semicolon may be omitted
showMessage  { MESSAGE 'Hello World!'; }

// context-independent ABSTRACT operator
loadImage 'Upload image' ABSTRACT (Item);

// explicit parameter list, body with several action operators and a LOCAL property
copy (Item from, Item to)  {
    LOCAL temp = STRING[100] ();
    temp() <- name(from);
    name(to) <- temp();
}

// abstract action with a return class
getPrice (Item i) ABSTRACT NUMERIC[10,2];

// context-independent INTERNAL operator — inline Java snippet
ping INTERNAL <{ System.out.println("ping"); }>;

// action with options — placed in toolbar, asks for confirmation when run
deleteItem (Item i)  { DELETE i; } TOOLBAR CONFIRM;