44 lines
1.1 KiB
Elixir
44 lines
1.1 KiB
Elixir
defmodule Counter.Worker do
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use GenServer # use builtint Elixir Generic Server
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### Client API ###
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def inc(amt \\ 1) do
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GenServer.cast(__MODULE__, {:inc, amt})
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end
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def dec(amt \\ 1) do
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GenServer.cast(__MODULE__, {:dec, amt})
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end
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def value() do
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GenServer.call(__MODULE__, :value)
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end
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### Server Impl ###
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def start(n \\ 0) do
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# use module name as name for registered server
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# now inc, dec, and value dont need pid, and can use __MODULE__
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GenServer.start(__MODULE__, n, name: __MODULE__)
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end
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@impl true # annotation that signature agrees with callback
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def init(arg) do # arg comes from 2nd arg of GenServer.start
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{:ok, arg}
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end
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@impl true
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def handle_call(:value, _from, state) do
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{:reply, state, state} # {:reply, actual_reply, new_state}
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end
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@impl true
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def handle_cast({:inc, amt}, state) do
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{:noreply, state + amt} # {:noreply, new_state}
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end
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@impl true
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def handle_cast({:dec, amt}, state) do
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{:noreply, state - amt} # {:noreply, new_state}
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end
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end
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