Add AV1002: Only pass things to a constructor that most or all members need

[dennisdoomen]

This PR adds guideline AV1002.

It was split out of #298 so the change can be reviewed independently.

Files:

• _rules/1002.md

Part of the replacement for #298.

[bkoelman]

This is a bit vague regarding injected dependencies.

• "If a dependency is only used by one or two members out of many..." -> don't
• "Cross-cutting concerns may reasonably be injected even if not every member uses them directly." -> do

So, suppose we define a class with 5 members, and only one needs the IClock abstraction. What should I do? If it's a method, I can take a parameter (placing the burden on the caller to explicitly pull it from the service container). But if the member concerns a property (for example: CacheEntry.IsStale), I need to change it into a method first.

I think it would help to distinguish between the kinds of parameters: values and dependencies. Then the rule definition can be about values, while the exception is about dependencies.

[dennisdoomen]

Yes, you're right, and I don't think we can define this rule in such a way it is comprehensive enough to provide clear guidance. Unless you know a better way.

[bkoelman]

Another issue with this rule is that API breaking changes are required if the implementation changes. For example, in the current version, the parameter X is omitted from the constructor because it's used by only two members. In the next version, a new member that also depends on X is added, so X must now be added as a constructor parameter and removed from the existing members.

I think we should drop this rule.