sandbox/pe/afile_server.erl

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2019-04-22 02:25:01 +00:00
-module(afile_server).
-compile([debug_info]).
-export([start/1, loop/1]).
start(Dir) ->
spawn(afile_server, loop, [Dir]).
%% Three significant points to observer about this code:
%%
%% + Who to reply to: all the received messages contain
%% the variable Client - the PID of the sender.
%% + Use of self(): the PID of the server.
%% + Pattern matching to select the message.
loop(Dir) ->
receive
{Client, list_dir} ->
Client ! {self(), file:list_dir(Dir)};
{Client, {get_file, File}} ->
Full = filename:join(Dir, File),
Client ! {self(), file:read_file(Full)};
{Client, {put_file, File, Contents}} ->
Full = filename:join(Dir, File),
Client ! {self(), file:write_file(Full, Contents)},
{Client, ping} ->
Client ! {self(), pong};
{Client, _} ->
Client ! {self(), unrecognised_message};
{_} ->
io:format("unhandled message")
end,
loop(Dir).
%% Notes:
%% + function names are always lowercased
%% + universal receiver: receive X -> X end.
%% + erlang: use processes to structure the solutions to our problems.
%% + *ATOMS*ARE*LOWER*CASED*