A response definition consists of two kinds of statements. A response statement specifies the stimulus, or event, that is to invoke a response. Action statements specify the actions that ESL is to perform when a particular stimulus is recognized.
Note: You can specify a response statement with zero action statements. For example, you might want to clear the buffer in response to certain characters that you know will be sent from an application; or, when you create a prototype interface, you might have a response to an object that will eventually send a string to an application.
For example:
response to MakeRed # response statement
make BigBox red # action statement
make BigBox visible # action statement
send "Red \n" to Recorder # action statement
Each response statement specifies a stimulus to which ESL can respond. You specify a response statement as the first statement in a response definition. Following the response statement, you can specify any number of action statements. The complete set of response statements is as follows:
Response Statement |
Invoked |
response to start |
When the ESL program is initiated, or when a block is first entered. |
[interrupt] response to OBJECT |
When the user selects an object. |
[interrupt] response to item |
When the user selects an action bar item. |
[interrupt] response to line or [interrupt] response to char |
When the program receives data from the keyboard or from an application program. |
response to low memory |
When ESL reaches a specified threshold of available memory during runtime. |
[interrupt] response to interval |
At specified intervals (in seconds) during runtime. |
response to stimulus |
When a stimulus library generates an event. |
[interrupt] response to timeout |
When ESL does not receive any stimulus for a specified number of seconds. |
response to termination |
When a block is left implicitly. |
In summary, ESL responds to the following stimuli:
•Initiation of the ESL program, or of a defined block of responses.
•Selecting an object on the screen (with any pointing device).
•Selecting an item from an action bar on the screen (with any pointing device).
•Entering data from the keyboard.
•Receiving data from an application program.
•Elapsed time.
•When a stimulus library generates an event.
•Lack of any stimuli during elapsed time.
•When a block is left implicitly.
