Delegates: Difference between revisions

=={{header|Julia}}==

'''Module''':

<lang julia>module Delegates

export Delegator, Delegate

struct Delegator{T}

delegate::T

end

struct Delegate end

operation(x::Delegator) = thing(x.delegate)

thing(::Any) = "default implementation"

thing(::Delegate) = "delegate implementation"

end # module Delegates</lang>

'''Main''':

<lang julia>using .Delegates

a = Delegator(nothing)

b = Delegator("string")

d = Delegate()

c = Delegator(d)

@show Delegates.operation(a)

@show Delegates.operation(b)

@show Delegates.operation(c)</lang>

{{out}}

<pre>Delegates.operation(a) = "default implementation"

Delegates.operation(b) = "default implementation"

Delegates.operation(c) = "delegate implementation"</pre>