59 lines
2.1 KiB
Ruby
59 lines
2.1 KiB
Ruby
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module EventMachine
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# Utility method for coercing arguments to an object that responds to :call.
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# Accepts an object and a method name to send to, or a block, or an object
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# that responds to :call.
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#
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# @example EventMachine.Callback used with a block. Returns that block.
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#
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# cb = EventMachine.Callback do |msg|
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# puts(msg)
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# end
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# # returned object is a callable
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# cb.call('hello world')
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#
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#
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# @example EventMachine.Callback used with an object (to be more specific, class object) and a method name, returns an object that responds to #call
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#
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# cb = EventMachine.Callback(Object, :puts)
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# # returned object is a callable that delegates to Kernel#puts (in this case Object.puts)
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# cb.call('hello world')
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#
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#
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# @example EventMachine.Callback used with an object that responds to #call. Returns the argument.
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#
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# cb = EventMachine.Callback(proc{ |msg| puts(msg) })
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# # returned object is a callable
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# cb.call('hello world')
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#
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#
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# @overload Callback(object, method)
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# Wraps `method` invocation on `object` into an object that responds to #call that proxies all the arguments to that method
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# @param [Object] Object to invoke method on
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# @param [Symbol] Method name
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# @return [<#call>] An object that responds to #call that takes any number of arguments and invokes method on object with those arguments
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#
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# @overload Callback(object)
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# Returns callable object as is, without any coercion
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# @param [<#call>] An object that responds to #call
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# @return [<#call>] Its argument
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#
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# @overload Callback(&block)
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# Returns block passed to it without any coercion
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# @return [<#call>] Block passed to this method
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#
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# @raise [ArgumentError] When argument doesn't respond to #call, method name is missing or when invoked without arguments and block isn't given
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#
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# @return [<#call>]
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def self.Callback(object = nil, method = nil, &blk)
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if object && method
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lambda { |*args| object.__send__ method, *args }
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else
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if object.respond_to? :call
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object
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else
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blk || raise(ArgumentError)
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end # if
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end # if
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end # self.Callback
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end # EventMachine
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