46 lines
1.3 KiB
Erlang
46 lines
1.3 KiB
Erlang
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-module(error_test).
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-export([generate_exc/1, demo1/0, demo2/0, demo3/0, catcher/1]).
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generate_exc(1) -> a;
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generate_exc(2) -> throw(a);
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generate_exc(3) -> exit(a);
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generate_exc(4) -> {'EXIT', a};
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generate_exc(5) -> error(a).
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demo1() ->
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[catcher(I) || I <- lists:seq(1, 5)].
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demo2() ->
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[{I, (catch generate_exc(I))} || I <- [1,2,3,4,5]].
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catcher(N) ->
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try generate_exc(N) of
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Val -> {N, normal, Val}
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catch
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throw:X -> {N, caught, thrown, X};
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exit:X -> {N, caught, exited, X};
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error:X -> {N, caught, error, X}
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end.
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%% NB: catch _ -> ... assumes default tag throw, need to specify
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%% catch _:_ -> ...
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demo3() ->
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try generate_exc(5)
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catch
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error:X ->
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{X, erlang:get_stacktrace()}
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end.
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%% In Erlang, when an error is detected internally by the system or is
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%% detected by program logic, the correct approach is to crash
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%% immediately and generate a meaningful error message. We crash
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%% immediately so as not to make matters worse. The error message should
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%% be written to a permanent error log and be sufficiently detailed so
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%% that we can figure out what went wrong later.
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%%
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%% Second, fail politely means that only the programmer should see the
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%% detailed error messages produced when a program crashes. A user of the
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%% program should never see these messages.
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