Exceptions: Difference between revisions
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FI |
FI |
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</pre> |
</pre> |
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===Standard |
===Standard Prelude "on event" routines=== |
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ALGOL 68 uses event routines extensively in the "standard transput" |
ALGOL 68 uses event routines extensively in the "standard transput" |
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(stdio) to manage the various events that arise when data is read |
(stdio) to manage the various events that arise when data is read |
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All of the above allow the programmer to define a user created event |
All of the above allow the programmer to define a user created event |
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routine when a particular event happens to a particular FILE. When such an |
routine when a particular event happens to a particular FILE. When such an |
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event routine is called, then the routine can use any of the standard |
event routine is called, then the routine can use any of the standard prelude |
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routine to reposition the FILE and rectify the detected event, eg: |
routine to reposition the FILE and rectify the detected event, eg: |
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* space or back space |
* space or back space |
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The handler is permitted to return TRUE depending on whether the event |
The handler is permitted to return TRUE depending on whether the event |
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has been handled and the program can can continue. And FALSE is when event |
has been handled and the program can can continue. And FALSE is when event |
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remains unhandled, and the standard |
remains unhandled, and the standard prelude event routine should be used. The |
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handler is also permitted to exit to a label (without returning anything) if the |
handler is also permitted to exit to a label (without returning anything) if the |
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user defined event routine determines that processing is complete. |
user defined event routine determines that processing is complete. |
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