Allow setting context via command line

[RyanZim]

As mentioned in #51.

Currently, we have --env to allow setting process.env.NODE_ENV for postcss.config.js. We also have command-line flags to override the syntax, parser, stringifier, & map options specified in the config.

We should have an additional command-line flag to allow passing other values via ctx to postcss.config.js.

My strawman proposal:

postcss --ctx {doIt: true, someKey: 'somevalue'}

This needs discussion.

[RyanZim]

@michael-ciniawsky ping?

[michael-ciniawsky]

I currently expose the config.options to ctx

postcss src/index.sss -o dest/index.css -p sugarss -m -e 'production' 

module.exports = ({ options, file, env }) => ({
   parser: file.extname === '.sss' ? options.parser : false
   map: options.map || { inline: true }
   plugins: {
     'postcss-import': { root: file.dirname }
     'cssnano': env === 'prodution' ? {} : false
   }
})

The following is not working and is a mess, how did postcss-cli v2 --use work ? Something like options.plugins.key = value would still be valuable though. For --use and postcss.config.js

postcss -u || --ctx  { key: value }

[RyanZim]

@michael-ciniawsky So what are we doing here?

[michael-ciniawsky]

Options can be set via the CLI, only plugin options must be defined in the config itself

postcss -m -p -t -s

postcss.config.js

module.exports = (ctx) => ({
   map: cts.options.map || fallback,
   parser: ctx.options.parser || fallback,
   syntax: ctx.options. syntax,
   stringifier: ctx.options.stringifier
   plugins: {...plugins}
})

[RyanZim]

So we don't need custom context?

[michael-ciniawsky]

Well It would into the direction like -- ctx ctx.key value which is similiar to -u plugin.option value and we decided to not support atm. In the future we can try to add the -u .. to the context e.g ctx.option.plugins

module.exports = (ctx) => ({
   map: cts.options.map || fallback,
   parser: ctx.options.parser || fallback,
   syntax: ctx.options. syntax,
   stringifier: ctx.options.stringifier,
   plugins: { 
     'posthtml-plugin': ctx.options.plugin
   }
})

[RyanZim]

In the future we can try to add the -u .. to the context e.g ctx.option.plugins

👍 Perhaps should be ctx.plugins, but, yeah.

---

Can you document what's currently available via ctx?

[michael-ciniawsky]

Yep ctx.plugins of course 😛 . yep I will make docs about it

[michael-ciniawsky]

Fixed by #86