Distributing a buildable executable

[Р.С. Алиев]

08.01.2020 17:31, Dave Cottlehuber пишет:
> On Tue, 7 Jan 2020, at 16:04, Р.С. Алиев wrote:
>> Hello list,
>>
>> What I have is:
>> 1. Pure Erlang part, a simple gen_server;
>> 2. Several C++ source files + cmake file, intended to be build into a
>> standalone executable.
>>
>> I need to distribute both components in a single package, as my
>> gen_server does open_port({spawn, my_executable}). Moreover, it uses an
>> environmental variable to find the executable, so I need a way to set it
>> too (I use the "QT5_EPORT_DIR=~/Path/to/executable rebar3 shell --apps
>> my_app" command now, but it obviously needs to be generalized somehow).
>>
>> What is the standard way to distribute such a two-component Erlang package?
>> Thank you.
>>
>>
>> -- 
>> Regards,
>> R.S. Aliev
> 
> Hey RS,
> 
> Distribute the binary in your application priv directory, & then however you
> deploy your app, you can check for & locate the binary at module load time:
> 
> ```erl
> -module(flux_capacitor).
> -on_load(init/0).
> ...
> init() ->
>      PrivDir = case code:priv_dir(?MODULE) of
>          {error, _} ->
>              %% ENOIDEA so make a wild guess
>              EbinDir = filename:dirname(code:which(?MODULE)),
>              AppPath = filename:dirname(EbinDir),
>              filename:join(AppPath, "priv");
>          Path ->
>              Path
>      end,
>      do_stuff(filename:join(PrivDir, "executable")).
> ```
> 
> Alternatively for a gen_server you might handle this in Module:init/1.
>   
> see jiffy and associated rebar.config for how this all gets assembled.
> 
> https://github.com/davisp/jiffy/blob/master/src/jiffy.erl#L181-L190
> 
> There's a bunch more useful stuff in Paul's nif-examples[1] repo,
> albeit targeted for NIFs obviously. If you need to compile the exe,
> enc[2] is the best rebar-ish extension I've used for this, but I don't
> know off-hand of any cmake-driven builds.
> 
> [1]: https://github.com/davisp/nif-examples/tree/master/apps
> [2]: https://github.com/davisp/erlang-native-compiler
> 
> A+
> Dave
> 

Hey Dave,

Thank you for the hints. I have no problem with NIFs and definitely 
wouldn't want to go that way here. The binary in question is intended to 
act as a server, without any knowledge of the client's particularities 
(thence erlang:port_command/2 etc).

The idea i was toying in my head is to just run cmake && cp in the said 
gen_server's init. But that seems kinda unholy. So, i'll try enc.

Thanks again. The source code is at https://bitbucket.org/r_s_o/epona, 
if you are interested. It is Qt5 GUI builder tool, somewhat similar to 
wxErlang, but simpler and much more declarative (see demo_gs.erl). Any 
suggestions are greatly appreciated.


-- 
Regards,
R.S. Aliev