Mix deps.add functionality

Never thought I’ll ever compare Node and Elixir, but here I go…
Why don’t we have something similar to npm i(nstall) --save dependency@version with Mix? All the Node-world libraries have step 1 of the installation guide "run npm i --save this_lib@1.2.3" while all the Elixir-world libraries have step 1 "open mix.exs and add a dependency to the list of your dependencies like {this_lib, "~> 1.2.3"}. It can be better in terms of versions micro-management, name-collisions etc., but isn’t it all the same for npm? I think it would be really nice to have something like mix deps.add the_lib and I’m really not getting why don’t we have it so far.


It’s a bit more complicated with mix.exs because unlike node’s package.json it’s not a structured file format (i. e. XML or JSON) which makes parsing and modifying it much harder.
Not only that, but It doesn’t even necessarily follow the same patterns for each project. While it is common to have a private deps/0 function as part of a MyApp.Mixfile module, one could decide to go about things in a completely different way.


Sure truth, but I think if we had a mix deps.add for the very basic Elixir app with a single deps/0 function in mix.exs, that would be great.

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Honestly, I think because really the time it takes to add it to mix.exs and to run mix deps.get is trivial. As developers laziness can be a good thing, but sometimes doing two steps instead of one isn’t that big of a deal. You could implement this on your own via a bash script using sed, but is it worth your time to automate this one step?


Using sed will be more complicated because will depend on a strict format of the function itself and there’s already something like that done here: https://github.com/bryanstearns/mix_deps_add. If the only reason for not having this is “time spent doesn’t seems to be worth it”, then I’m the one who is ready to spend time on this. I think that’s exactly what I want to hear: “we don’t have it because it doesn’t worth time adding” or “we don’t have it because the idea is wrong (because …)”.

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Ok, that appeared to be more tricky than I thought - simple “read, parse/update and write ast” approach appeared to be not enough since all the formatting/comments/etc. is getting lost due to not being part of ast.

Yeah, the Elixir AST is heavily processed, it is not reversible like it is for other languages like C++ or so. However it is significantly more simple and easy to work with, just not reversible. :slight_smile:

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@chvanikoff reading your thread I am/was looking to do the same exact thing you are. We should talk about it some more.

I was talking to @fishcakez about automating https://github.com/ElixirCommons/ElixirProjectChecklist

I am referencing the other thread here: Parse Elixir Module AST to replace functions and replace the original source file?