[erlang-questions] Dot before call in EUNIT

Richard Carlsson <>
Fri Nov 23 14:39:57 CET 2012


Hi! This artefact is just so that the eunit header file will work also 
in modules that use "packages" (experimental, now deprecated, so 
eunit.hrl can be updated when packages support is removed from OTP).

     /Richard

On 2012-11-23 13:46, Dmitry Klionsky wrote:
> Hi everybody!
>
> I was looking inside eunit.hrl and found a number of defines like this one:
>
> -define(assertMatch(Guard, Expr),
>      ((fun () ->
>          case (Expr) of
>          Guard -> ok;
>          __V -> .erlang:error({assertMatch_failed,
>                        [{module, ?MODULE},
>                         {line, ?LINE},
>                         {expression, (??Expr)},
>                         {pattern, (??Guard)},
>                         {value, __V}]})
>          end
>        end)())).
> -endif.
>
> What is interesting for me is the DOT before the call. I've never seen
> it before. I've googled, but found nothing.
>
> Then I grepped:
> /opt/otp-r15b01/lib/erlang/lib $ grep -E ' \.[a-z]+:[a-z]+' ./*/*/*.{e,h}rl
>
> ./eunit-2.2.2/include/eunit.hrl:
> .erlang:process_info(.erlang:group_leader(),
> ./eunit-2.2.2/include/eunit.hrl:        __V ->
> .erlang:error({assertion_failed,
> ./eunit-2.2.2/include/eunit.hrl:        __V ->
> .erlang:error({assertMatch_failed,
> ./eunit-2.2.2/include/eunit.hrl:        Guard ->
> .erlang:error({assertNotMatch_failed,
> ./eunit-2.2.2/include/eunit.hrl:        __V ->
> .erlang:error({assertEqual_failed,
> ./eunit-2.2.2/include/eunit.hrl:        __X ->
> .erlang:error({assertNotEqual_failed,
> ./eunit-2.2.2/include/eunit.hrl:            __V ->
> .erlang:error({assertException_failed,
> ./eunit-2.2.2/include/eunit.hrl: .erlang:error({assertException_failed,
> ./eunit-2.2.2/include/eunit.hrl: .erlang:get_stacktrace()}}]})
> ./eunit-2.2.2/include/eunit.hrl: .erlang:error({assertNotException_failed,
> ./eunit-2.2.2/include/eunit.hrl: .erlang:get_stacktrace()
> ./eunit-2.2.2/include/eunit.hrl:        {__N, _} ->
> .erlang:error({command_failed,
> ./eunit-2.2.2/include/eunit.hrl:        {__N, _} ->
> .erlang:error({assertCmd_failed,
> ./eunit-2.2.2/include/eunit.hrl:        {_, __T} ->
> .erlang:error({assertCmdOutput_failed,
> ./eunit-2.2.2/include/eunit.hrl:         .io:fwrite(user, <<"~s:~w:~w:
> ~s\n">>,
>
> So only EUNIT uses this notation. It seems like a historical artifact
> left from ancient times.
> My question is mainly to erlang veterans. What this DOT is/was about?
>
> Best regards,
> Dmitry Klionsky
>
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> 
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