Adding prompts to blueprints

[anithri]

If we use the blueprint subcommand options (#106) and add a prompt: "ask a question" to the options, we can use the generate-from-blueprint to create user prompts to gather the requested data.

The we can refactor the bp init command such that bp init . does the same as bp generate blueprintrc .blueprintrc path=.

The big hurdle to this is making generate-from-blueprint.js task able to collect information from the user as prompts.

[jamesr73]

In terms of blueprint options specified as yargs options this could prove to be a chicken-and-egg problem.

I can envisage extracting info from yargs options to save on the Blueprint object. And caching loaded Blueprints such that generate-from-blueprint.js has access to those when it runs. But if they are defined as required then yargs has already forced the user to specify them. And if they are optional it could frustrate the user to be prompted for information they didn't want to provide.

There may be a middle ground if we give up the full power of yargs and only support the "options object" format of yargs configuration. This would allow us to specify yargs options in a simple object that we could separately interrogate for prompting. In this case we would have most/all options optional for yargs but flagged with a prompt for input from the user.

We could of course support both... if the blueprint options are specified as an object we can have this functionality but if they are specified as a yargs builder function we cannot. Or we can separate the concerns and have a separate definition in the blueprint for prompts vs command line arguments.

[anithri]

required is for yargs. prompt is for generate.

If required and not present, cli quits

If prompt and not present, generate-from-blueprint.js does a prompt

[jamesr73]

Updated #110 so that custom options must be specified as a plain object in order to support this.

[jamesr73]

Might be interesting to resurrect yargs 286