Exceptions: Difference between revisions
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===Defining exceptions=== |
===Defining exceptions=== |
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Exceptions can only be declared at the "top-level" of a module or interface. Arguments are optional. |
Exceptions can only be declared at the "top-level" of a module or interface. Arguments are optional. |
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<lang modula3>EXCEPTION EndOfFile; |
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<pre> |
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EXCEPTION |
EXCEPTION Error(TEXT);</lang> |
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EXCEPTION Error(TEXT); |
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</pre> |
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===Throw exceptions=== |
===Throw exceptions=== |
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Exceptions can be bound to procedures using RAISES: |
Exceptions can be bound to procedures using RAISES: |
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| ⚫ | |||
<pre> |
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| ⚫ | |||
... |
... |
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RAISE EndOfFile; |
RAISE EndOfFile; |
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... |
... |
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</ |
</lang> |
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===Catching exceptions=== |
===Catching exceptions=== |
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<lang modula3>TRY |
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<pre> |
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TRY |
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Foo(); |
Foo(); |
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EXCEPT |
EXCEPT |
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| EndOfFile => HandleFoo(); |
| EndOfFile => HandleFoo(); |
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END; |
END;</lang> |
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</pre> |
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Modula-3 also has a FINALLY keyword: |
Modula-3 also has a FINALLY keyword: |
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<lang modula3>TRY |
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<pre> |
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TRY |
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Foo(); |
Foo(); |
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FINALLY |
FINALLY |
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CleanupFoo(); (* always executed *) |
CleanupFoo(); (* always executed *) |
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END; |
END; |
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</ |
</lang> |
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=={{header|OCaml}}== |
=={{header|OCaml}}== |
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