review config API about bluge HOT 2 OPEN

So, the design of Bluge's Config was influenced heavily by dgraph's BadgerDB Options structure: https://github.com/dgraph-io/badger/blob/master/options.go#L26

I personally found it awkward when I first used BadgerDB, but over time I came to appreciate some of the way it worked. Here are some of the aspects of the design:

1. Struct members are mostly public
2. User-facing options/config settings named X have a corresponding WithX() function to set them
3. All these methods return a copy of the struct itself (this allows method chaining)
4. A default config is created using a function
5. Constructors taking the config also pass by copy

Things I like about this:

• Constructor taking copy means we generally aren't worried about people changing the config after they passed it in because we own our copy (NOTE: still have to be careful with the contents of the config)
• Also because of the copies, it's possible to reuse config definitions (again, must be careful that contents are not pointers to things with state) This is highly desirable for expressing configuration in one (or few) places and reusing many places safely.
• The method chaining feels very convenient for expressing configuration:

cfg := DefaultConfig(path).
    WithX(x).
    WithY(y)

To me, this is very readable. Subjectively, it is more readable than if the methods were called SetX(x).

Things I don't like about this:

• Config object can be large, and passed by copy means static analysis (and soon possibly go tooling itself) may warn about copying large objects. I've made peace with this as config objects are typically worked with infrequently.

from bluge.

So, with that as the background, @steveyen, I'd like to better understand your criticism. As I understood it you don't like a method named WithX(x) for an option named X. Here are some alternatives:

• Method named SetX(x), option named X
• Method named X(x) option named x

My thinking is that SetX(x) is more standard in Go, but perhaps less readable in this case, because it implies you've mutated the object, when in fact, we're returning a new one.

My thinking is that X(x) is simply confusing because it lacks a verb describing the action.

Your thoughts?

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