Install peerDependencies

[ericclemmons]

When using this webpack plugin in a project using @cycle/core which has rx as peer dependency I met an infinite loop:

node_modules/.bin/webpack
ts-loader: Using typescript@1.8.10 and /Users/chadrien/src/ml/tsconfig.json
Installing `@cycle/core`...
/Users/chadrien/src/ml
├── @cycle/core@6.0.3  extraneous
└── UNMET PEER DEPENDENCY rx@*

npm WARN @cycle/core@6.0.3 requires a peer of rx@* but none was installed.
npm WARN ml No description
npm WARN ml No repository field.
npm WARN ml No license field.
Installing `@cycle/core`...
/Users/chadrien/src/ml
├── @cycle/core@6.0.3  extraneous
└── UNMET PEER DEPENDENCY rx@*

npm WARN @cycle/core@6.0.3 requires a peer of rx@* but none was installed.
npm WARN ml No description
npm WARN ml No repository field.
npm WARN ml No license field.
Installing `@cycle/core`...
/Users/chadrien/src/ml
├── @cycle/core@6.0.3  extraneous
└── UNMET PEER DEPENDENCY rx@*

And going on until a hit ctrl-c

Maybe an approach to this would be to install the peer dependencies of a package if it has any.

[chadrien]

My bad, I was hitting the infinite loop because I had neither a .npmrc nor setting {save: true} in the plugin configuration.

But the fact that peer dependencies could/should be installed as well remain

[ericclemmons]

@chadrien Hey, I'm back from vacation. Funny, I use @cycle/core as my test to ensure namespaced dependencies are installed :)

Anyway, I think this is a great feature. It actually annoyed me how, with v3.1.0 nearing release, I still had to exit to the terminal to install rx.

Luckily it looks like this should be a cinch, as parsing the error from the previous install is possible and npm install accepts ranges:

$ npm install sax@">=0.1.0 <0.2.0"
$ npm install @myorg/privatepackage@">=0.1.0 <0.2.0" 

[ericclemmons]

With #13 I'm going to change the save options to be either --save or --save-dev, which will solve the cyclical problem.

[ericclemmons]

I can foresee this being a problem for any aliased package (e.g. react is aliased as react-lite) that we'd ignore UNMET PEER DEPENDENCY errors for.

However, I'm willing to overlook that, since it just means a duplicate dependency may be installed, but never used.

[ericclemmons]

Ok, I think I got it!