Erlang: How to pass a path string to a function? - erlang

Question

I created a new file, based on OTP gen_server behaviour.
This is the begining of it:
-module(appender_server).
-behaviour(gen_server).
-export([start_link/1, stop/0]).
-export([init/1, handle_call/3, handle_cast/2]).
start_link(filePath) ->
gen_server:start_link({local, ?MODULE}, ?MODULE, filePath, []).
init(filePath) ->
{ok, theFile} = file:open(filePath, [append]). % File is created if it does not exist.
...
The file compiled ok using c(appender_server).
When I try to call start_link function from the shell, like this:
appender_server:start_link("c:/temp/file.txt").
I get:
** exception error: no function clause matching appender_server:start_link("c:/temp/file.txt") (appender_server.erl,
line 10)
What do I do wrong?

Answer 1

filePath is an atom--not a variable:
7> is_atom(filePath).
true
In erlang, variables start with a capital letter. The only way erlang could match your function clause would be to call the function like this:
appender_server:start_link(filePath)
Here is an example:
-module(a).
-compile(export_all).
go(x) -> io:format("Got the atom: x~n");
go(y) -> io:format("Got the atom: y~n");
go(X) -> io:format("Got: ~w~n", [X]).
In the shell:
3> c(a).
a.erl:2: Warning: export_all flag enabled - all functions will be exported
{ok,a}
4> a:go(y).
Got the atom: y
ok
5> a:go(x).
Got the atom: x
ok
6> a:go(filePath).
Got: filePath
ok
7> a:go([1, 2, 3]).
Got: [1,2,3]
ok
8>