Wie erstellt Procs mit variablen Argumenten in Crystal?

Question

Ich möchte Argumente in ein Proc wie splat mit zu übergeben, aber es gibt einen Fehler wrong number of block arguments (1 for 0)

$callbacks = {} of String => Array(->) 

def add_callback(event, &block) 
    begin 
    $callbacks[event.to_s] << block 
    rescue 
    $callbacks[event.to_s] = [block] 
    end 
end 

add_callback(:event) do |arg| 
    puts "event!" 
end 

$callbacks["event"].first.call 

Error in line 11: wrong number of block arguments (1 for 0)http://carc.in/#/r/7gw

Answer 1

Sie müssen überall die Argumentliste angeben.

class EventManager 
    def initialize 
    @callbacks = Hash(String, Array(String ->)).new {|h, k| h[k] = [] of String -> } 
    end 

    def add(event, &callback : String ->) 
    @callbacks[event] << callback 
    end 

    def fire(event, argument : String) 
    @callbacks[event].each &.call(argument) 
    end 
end 

callbacks = EventManager.new 
callbacks.add("foo") do |argument| 
    puts "Got #{argument}" 
end 
callbacks.add("bar") do 
    puts "I was called" 
end 
callbacks.fire "foo", "Ping" 
callbacks.fire "bar", "Pong"