loop
| Syntax |
loop statements or, loop (statement1; expression; statement2) statements
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| Action |
In its simplest form, where the loop expression is not provided, the loop statement executes its body statements repeatedly, forever. Such a loop can be terminated by a break or return statement, or by the user canceling the script.
In its more complex form, the loop statement is executed as follows: 1. statement1 is executed; 2. expression is evaluated;
As long as expression evaluates to true, 3. the body statements are executed; 4. statement2 is executed; 5. expression is re-evaluated.
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| Examples |
loop (w = window.frontmost (); w != ""; w = window.next (w)) {msg (w)}
This loop iterates through all open windows, posting a message with their titles in the Main Window. break msg ("It's" + clock.now () + "you still haven't clicked the mouse!")
This loops until the user presses the mouse button, while posting a message of impatience. |
| Notes |
The complex loop form is most appropriate when the three expressions work together to control the loop iterations, as in the first example above. statement1 is executed only once; statement2 is executed after each iteration over the loop body. If expression initially evaluates to false, the loop body (and statement2) will not be executed even once. The action of the complex loop statement is almost identical to the following while statement: statement1 while expression statements statement2 However, a continue statement in the while body would not cause statement2 to be executed before the next loop iteration, as it does with the loop statement. For simple counting loops, the for loop construct is simpler and more efficient.
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| See Also |
for
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