krpc-rb Events API

krpc_events.rb

##
##  Some non-binding thoughts on krpc-rb Events API.
##    (This API Concept is probably too high-level.)
##

KRPC.connect do |client|
  v = client.space_center.active_vessel

  # Fires once
  v.orbit.once :apoapsis_altitude, :change do |apo|
    puts "new apoapsis: #{apo}"
  end
  
  # Fires multiple times
  v.orbit.when :apoapsis_altitude, :change do |apo|
    puts "new apoapsis: #{apo}"
  end

  # Condition
  v.orbit.when :apoapsis_altitude, below: 20.km do |apo|
    puts "apoapsis below 20, exactly #{apo}"
  end
  
  # Once + Argumet to RPC method + Condition
  v.resources.once :amount, 'SolidFuel', equals: 0 do
    # Separate those SRBs!
  end

  # Condition using proc/lambda
  v.orbit.when :apoapsis_altitude, ->{|apo| apo < 20.km} do |apo|
    puts "apoapsis below 20, exactly #{apo}"
  end

  # Condition using proc/lambda (version 2)
  v.orbit.when ->{|o| o.apoapsis_altitude < 20.km} do |orbit|
    puts "apoapsis below 20, exactly #{orbit.apoapsis_altitude}"
  end
  
  # Complex condition using expressions
  ve = v.to_expr
  v.orbit.once :apoapsis_altitude, above: ve.orbit.body.atmosphere_depth.plus(2.km) do |apo| ## OR
  v.orbit.once :apoapsis_altitude, above: ->(e){ e.body.atmosphere_depth.plus(2.km) } do |apo| ## OR
  v.orbit.once :apoapsis_altitude, above: [:body, :atmosphere_depth] do |apo|
    puts "above atmosphere"
  end

  oe = v.orbit.to_expr # The same as: KRPC::Expression.new(v.orbit)
  KRPC.once oe.apoapsis_altitude.gt(oe.body.atmosphere_depth) do |event|
    puts "above atmosphere"
  end
  
  # Debounce
  v.orbit.while :apoapsis_altitude, below: 80.km, debounce: 50 do |_|
    # nothing
  end

  # Remove event
  event = v.orbit.when :apoapsis_altitude, :change do |apo, event|
    puts "new apoapsis: #{apo}"
    event.cancel if apo > 100.km
  end
  sleep 1
  event.cancel # aliased as 'remove' and 'close' ???
  event.removed?

  # block - waiting for condition
  v.orbit.await :apoapsis_altitude, above: 80.km

  
  # Blocks until client#close is called, or all events are removed
  client.await_events

end


## Some links for fun:
## https://docs.python.org/3/library/concurrent.futures.html#concurrent.futures.Future
## https://docs.python.org/2/library/threading.html#event-objects