Exceptions: Difference between revisions
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=={{header|Phix}}== |
=={{header|Phix}}== |
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{{libheader|Phix/basics}} |
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Phix provides try/catch and throw statements. |
Phix provides try/catch and throw statements. |
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'''Throwing exceptions'''<br> |
'''Throwing exceptions'''<br> |
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You can throw any string (on it's own) or any integer, optionally with any (deeply nested) user_data that you like. |
You can throw any string (on it's own) or any integer, optionally with any (deeply nested) user_data that you like. |
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<lang Phix> |
<!--<lang Phix>--> |
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<span style="color: #008080;">throw<span style="color: #0000FF;">(<span style="color: #008000;">"oh no"<span style="color: #0000FF;">)</span> |
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throw(1) |
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<span style="color: #008080;">throw<span style="color: #0000FF;">(<span style="color: #000000;">1<span style="color: #0000FF;">)</span> |
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throw(501,{"she",made[me],Do(it)})</lang> |
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<span style="color: #008080;">throw<span style="color: #0000FF;">(<span style="color: #000000;">501<span style="color: #0000FF;">,<span style="color: #0000FF;">{<span style="color: #008000;">"she"<span style="color: #0000FF;">,<span style="color: #000000;">made<span style="color: #0000FF;">[<span style="color: #000000;">me<span style="color: #0000FF;">]<span style="color: #0000FF;">,<span style="color: #000000;">Do<span style="color: #0000FF;">(<span style="color: #000000;">it<span style="color: #0000FF;">)<span style="color: #0000FF;">}<span style="color: #0000FF;">) |
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'''Catching exceptions'''<br> |
'''Catching exceptions'''<br> |
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There is one and only one non-optional catch clause per try statement. <br> |
There is one and only one non-optional catch clause per try statement. <br> |
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The variable caught is a sequence, augmented with run-time diagnostics, with whatever was thrown in e[E_CODE] and/or e[E_USER]. |
The variable caught is a sequence, augmented with run-time diagnostics, with whatever was thrown in e[E_CODE] and/or e[E_USER]. |
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<lang Phix> |
<!--<lang Phix>--> |
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<span style="color: #008080;">try</span> |
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one_of(these) |
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<span style="color: #000000;">one_of<span style="color: #0000FF;">(<span style="color: #000000;">these<span style="color: #0000FF;">)</span> |
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catch e |
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<span style="color: #008080;">catch</span> <span style="color: #000000;">e</span> |
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if e[E_CODE]=501 then |
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<span style="color: #008080;">if</span> <span style="color: #000000;">e<span style="color: #0000FF;">[<span style="color: #000000;">E_CODE<span style="color: #0000FF;">]<span style="color: #0000FF;">=<span style="color: #000000;">501</span> <span style="color: #008080;">then</span> |
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puts(1,"that's no excuse!\n") |
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<span style="color: #7060A8;">puts<span style="color: #0000FF;">(<span style="color: #000000;">1<span style="color: #0000FF;">,<span style="color: #008000;">"that's no excuse!\n"<span style="color: #0000FF;">)</span> |
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else |
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<span style="color: #008080;">else</span> |
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throw(e) |
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<span style="color: #008080;">throw<span style="color: #0000FF;">(<span style="color: #000000;">e<span style="color: #0000FF;">)</span> |
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end if |
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<span style="color: #008080;">end</span> <span style="color: #008080;">if</span> |
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<span style="color: #008080;">end</span> <span style="color: #008080;">try |
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<!--</lang>--> |
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An uncaught exception terminates the program in error, otherwise control resumes in the catch clause or after the end try, |
An uncaught exception terminates the program in error, otherwise control resumes in the catch clause or after the end try, |
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with no means (apart from some really nasty inline assembly) of resuming any half-finished block of code, and indeed any |
with no means (apart from some really nasty inline assembly) of resuming any half-finished block of code, and indeed any |
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call stack entries between a throw and a catch will already have been torn down and thrown away.<br> |
call stack entries between a throw and a catch will already have been torn down and thrown away.<br> |
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Traditionally fatal errors are re-routed via throw() when the presence of an exception handler is detected.<br> |
Traditionally fatal errors are re-routed via throw() when the presence of an exception handler is detected.<br> |
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There is no finally construct |
There is no absurdly confusing finally construct - trivial to <del>mimic</del> better with the introduction of a single simple boolean flag anyway. |
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=={{header|PHL}}== |
=={{header|PHL}}== |
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