context

Allows to manage scoped data.

Usage

const someContext = new Context("some context name")

Read/write values

someContext.set("someKey", "someValue")
someContext.set("other key", new OtherValue())
const someValue = someContext.get("someKey")

Nesting

const subContext = someContext.enter("sub context")
try {
  subContext.set("sub value", new OtherValue())
  const someValue = someContext.get("someKey")  // Still get data from parent context
  subContext.set("someKey", "someSubValue")     // Now overrides parent value
} finally {
  subContext.leave()
}

Nested execution

A convenience method to automatically create a nested context and leaving it once executed.

const wasntDone = someContext.exec(nestedContext => (nestedContext, otherParam) => {
  const wasDone = nestedContext.get("nestedDone")
  nestedContext.set("nestedDone", true)
  return !wasDone
})

same for async functions:

const wasntDone = await someContext.execAsync(nestedContext => async(nestedContext, otherParam) => {
  const wasDone = nestedContext.get("nestedDone")
  await something()
  nestedContext.set("nestedDone", true)
  return !wasDone
})

Logging

A LoggedContext is a Context with a built-in Logger. It overrides the enter(), exec(), execAsync() APIs to set logging prefixes describing the current/nested context. For instance:

const someContext = new LoggedContext("some context")
someContext.logger.log("running")                     // Prints "some context: running"
const subContext = someContext.enter("sub context")
try {
  subContext.logger.log("running")                    // Prints "some context-sub context: running"
} finally {
  someContext.logger.log("stopping")                  // Prints "some context: stopping"
  subContext.leave()
}