How private are Erlang private functions? (2018)(medium.com)
medium.com
How private are Erlang private functions? (2018)
https://medium.com/about-erlang/how-private-are-erlang-private-functions-36382c6abfa4
8 comments
Cool trick. Best not to have debug enabled. Although by the time someone has an erl prompt in your cluster it's game over anyway.
This isn't super surprising. For all the Erlang I've used, I always had access to the source, so it'd be simple enough to modify the source (either directly, or through a code transformation), to get access to the nice function I want... it's kind of neat that you can decompile the beam files (at least if debug_info is present) and recompile with different options; and of course, being able to hot load (almost) everything is neat too.
I'm not a Erlang guru by any stretch of the imagination. But I would have thought that the privacy that matters the most in Erlang would be the privacy of being able to control what messages you respond to.
That being said, I thought the article was interesting in a pure hacker ethos sense. Like, the article isn't really about function visibility. It's about someone who knows how to do some esoteric things with an esoteric language.
Finally, with respect to Erlang itself. The language feels like it has everything you could possibly want (and this article is an example of that). However, I have always felt that discoverability of these Erlang capabilities has always been not that great. I was trying to do something with Erlang once upon a time (I honestly can't remember what it was) and I was having some trouble. Only to find that, apparently, there was a library that did exactly what I wanted included in the standard libs. With some sort of less than descriptive name. Great times.
That being said, I thought the article was interesting in a pure hacker ethos sense. Like, the article isn't really about function visibility. It's about someone who knows how to do some esoteric things with an esoteric language.
Finally, with respect to Erlang itself. The language feels like it has everything you could possibly want (and this article is an example of that). However, I have always felt that discoverability of these Erlang capabilities has always been not that great. I was trying to do something with Erlang once upon a time (I honestly can't remember what it was) and I was having some trouble. Only to find that, apparently, there was a library that did exactly what I wanted included in the standard libs. With some sort of less than descriptive name. Great times.
> However, I have always felt that discoverability of these Erlang capabilities has always been not that great.
I think the main reason is that the docs of stdlib are split between a number of "applications" (in OTP sense) and that there's no index of all the modules in one place (or I couldn't find one). So, starting here: https://www.erlang.org/docs/24/applications.html you need to open at least erts, kernel, and stdlib in separate tabs, and remember to search in all 3 for even basic things. And that's just library reference - there's also manual for Erlang, OTP, and many of the applications. Fortunately, manual and reference of the same app are often interlinked.
I think the main reason is that the docs of stdlib are split between a number of "applications" (in OTP sense) and that there's no index of all the modules in one place (or I couldn't find one). So, starting here: https://www.erlang.org/docs/24/applications.html you need to open at least erts, kernel, and stdlib in separate tabs, and remember to search in all 3 for even basic things. And that's just library reference - there's also manual for Erlang, OTP, and many of the applications. Fortunately, manual and reference of the same app are often interlinked.
Yea, you definitely need to pick through the standard lib to get an idea of what's there. Learned that lesson the hard way with Elixir when I tried to ignore all the Erlang stuff initially.
Is there a way to do this with Elixir?
Here’s a testing library that exposes private functions for testing. https://github.com/ihumanable/patch
Whether it’s a good idea to test private functions is a whole different issue…
Whether it’s a good idea to test private functions is a whole different issue…
call erlang from elixir.