The CurrencyRateController has been migrated to the BaseControllerV2
API, which includes various API changes. These changes include:
* The constructor now expects to be passed a
`RestrictedControllerMessenger`.
* State changes are subscribed to via the `ControllerMessenger` now,
rather than via a `subscribe` function.
* The state and configration are passed in as one "options" object,
rather than as two separate parameters
* The polling needs to be started explicitly by calling `start`. It
can be stopped and started on-demand now as well.
* Changing the current currency or native currency will now throw an
error if we fail to update the conversion rate.
The `ComposableObservableStore` has been updated to accomodate these
new types of controllers. The constructor has been updated to use an
options bag pattern as well, to make the addition of the new required
`controllerMessenger` parameter a bit less unweildly.
Three uses of `hasOwnProperty.call` have been replaced with simpler
alternatives. I did this because I found this convention confusing.
The `ComposableObservableStore` changes required adding a check for
whether the `config` is defined, because the old syntax would allow
iterating over `undefined` as if it was an empty object. Functionally
it should be identical. A new test was added to highlight this
functionality.
A few inconsistencies in JSDoc formatting have been fixed throughout
the project. Many issues remain; these were just the few things that
were easy to fix with a regular expression.
The changes include:
* Using lower-case for primitive types, but capitalizing non-primitive
types
* Separating the parameter identifier and the description with a dash
* Omitting a dash between the return type and the return description
* Ensuring the parameter type is first and the identifier is second (in
a few places it was backwards)
* Using square brackets to denote when a parameter is optional, rather
than putting "(optional)" in the parameter description
* Including a type and identifier with every parameter
* Fixing inconsistent spacing, except where it's used for alignment
* Remove incorrectly formatted `@deprecated` tags that reference non-
existent properties
* Remove lone comment block without accompanying function
Additionally, one parameter was renamed for clarity.
