allow specifying shell atts via config

[dsturnbull]

Status	Type	Config Change
Ready	Feature	Yes

Problem

Lots of nix shell configs require specifying an attribute.

Solution

Added a new config option where you can set the attr used.

New config parameters:

• nixEnvSelector.nixShellConfigAttr : optional attr

[arrterian]

@dsturnbull It's a really useful feature. Thanks a lot for your contribution. I left a review for your PR. Good job 🙂

[dsturnbull]

Thanks @arrterian. All these changes are fine, and in fact I started off with non-none Option type. The problem I can't figure out is how to use it in selectEnvCommandHander.

Please have a look at https://github.com/dsturnbull/nix-env-selector/pull/1 and see if you can see what the issue is :)

[arrterian]

@dsturnbull ohh miss one thing in the first review.

Action applyEnvByNixConfPath doesn't require any change. Just return original implementation and all should work fine.

Let's see on the current implementation

export const applyEnvByNixConfPath = (
  makeCmd: (path: string) => Option<string>
) => (nixConfigPath: string) =>
    of<Error, Option<string>>(makeCmd(nixConfigPath))
      .map(
        mapNullable(cmd =>
          node<Error, string>(done => exec(cmd, done))
            .map(parseEnv)
            .map(applyEnv)
        )
      )
      .chain(fold(() => of(false), id => id));

We have the only path arg applied to makeCmd and if we want to add the attribute to the CMD we need change only callback for creating the command, but not action executor. You changed both in your PR.

Now, lets see for getShellCmd type:

(internalCommand: "env", attr: Option<string>) => (path: string) => Option<string>

To satisfy our makeCmd type we just should apply this (internalCommand: "env", attr: Option<string>). You already have that in this line. https://github.com/dsturnbull/nix-env-selector/pull/1/commits/aeca6546f1e083a77d7e1b856654177ded3e3f7b#diff-45327f86d4438556066de133327f4ca2R53

So, to get the feature fully working just return current implementation for applyEnvByNixConfPath action.

[dsturnbull]

@arrterian thanks, please have a look now. :)

[arrterian]

@dsturnbull Fine! Just remove unused imports.

And one more thing before merging to the main codebase. Can you do rebase and squash the feature to a single commit? This need to avoid fixes message in history.

https://www.internalpointers.com/post/squash-commits-into-one-git

[arrterian]

@dsturnbull released

[dsturnbull]

Cheers @arrterian!