[for consideration] Move the notion of a 'online' block service to 'hasExchange'

[daviddias]

ref:

• Upgrade to new block and datastore interface #58 (comment)
• Upgrade to new block and datastore interface #58 (comment)

Once we start having more exchanges, it will make it more obvious why this is interesting.

[daviddias]

//cc @dignifiedquire

[dignifiedquire]

I forgot to respond in the PR sorry. I generally like the idea, the online and offline names are pretty confusing

[pgte]

Simply renaming .goOnline to .addExchange is not accurate, as it would overwrite the previous bitswap. Should it be setExchange?

[daviddias]

@pgte agreed. What about the 'disable', rmExchange?

[pgte]

That, or unsetExchange. Perhaps consider also acting on setExchange(null).

[dignifiedquire]

If the goal is to support multiple exchanges I wonder if it wouldn't be better to expose an api like this

.exchanges.ls()
// => returns an array of existing exchanges
.exchanges.add(newExchange)
// => adds a new exchange to the list
.exchanges.rm(existingExchange)
// => removes the given exchange (might want to this by name or id or something like that 
.exchanges.clear()
// => removes all exchanges
.exchanges.has()
// => alias for .ls().length > 0

[daviddias]

I'm good either way. I agree that if we get more than one exchange it will be good to have such an API, but at the same time, we don't have any other nor plans for it.

Right now what is important to get fixed is the misleading method name.

[daviddias]

Done with #67