Default configuration

[mthmulders]

There are a few things in MCS where the user is likely to (almost) always make the same choice. Which format to output a dependency management snippet in (Maven POM, Gradle, ...). Whether or not to copy a single result to the clipboard immediately (#184).

I think it would be nice if the user could configure some defaults for that, with the option of course to override when they use MCS.

I'll post one idea how to solve this, but I'm curious if there could be other ways in which MCS users see this work.

[mthmulders]

One way to address this could be a configuration file (let's say, ~/.mcs.properties). Upon invocation, MCS would read that file and treat its contents as if the user specified it on the command line. If the user specifies something on the command line that would also be present in the file, the command line should have preference.

[mthmulders]

Today I learned about picocli's support for "argument files" or "@-files". Quoting from their documentation:

Argument files are files that themselves contain arguments to the command. When picocli encounters an argument beginning with the character @, it expands the contents of that file into the argument list.

I feel this could be an easy approach to realise this "default configuration". If a file on the default path (hardcoded, let's say ~/.mcs/arguments) exists, it could be added to the user-supplied arguments.

Handling duplicates can be tricky though. Imagine a user has --format maven in their configuration file, passing --format maven on the CLI would result in

option '--format' (\<type>) should be specified only once

I'm not sure how much I like that last part - it feels a bit clunky. On the other hand, it seems like a relatively easy way to implement a "default configuration" - a lot easier than building it all from scratch.

[mthmulders]

Come to think of it a bit more, I think we should distinguish between two different concepts:

1. MCS options (such as --format) - this usually changes with every invocation
2. MCS configuration (such as a custom trust store or credentials for a remote REST API)

I think 2) is better scoped and much easier to implement than 1). I will try to give that a shot soon!

[mthmulders]

Idea formalised in #254, implementation ongoing in #255.