How to compile erlang code loaded into a string?
compilation, erlang
Solution
You need to scan your string into tokens, and then parse the tokens into forms. Unfortunately it is only possible to parse one form at a time, so you will need to either cut your string, or your tokens at form boundaries. Here is a short example:
% create tokens from strings containing forms
> {ok, MTs, _} = erl_scan:string("-module(z).").
> {ok, ETs, _} = erl_scan:string("-export([f/0]).").
> {ok, FTs, _} = erl_scan:string("f() -> hello_world.").
% tokens to erl_parse trees
> {ok,MF} = erl_parse:parse_form(MTs).
> {ok,EF} = erl_parse:parse_form(ETs).
> {ok,FF} = erl_parse:parse_form(FTs).
% compile forms to binary
> {ok, z, Bin} = compile:forms([MF,EF,FF]).
{ok,z,<<70,79,82,49,0,0,1,164,66,69,65,77,65,116,111,109,0,0,0,...>>}
% load module from binary
> code:load_binary(z, "nofile", Bin).
{module,z}
% test
> z:f().
hello_world
Alternatively you can scan your string, and then cut the resulting token list at `{dot, _}` tokens apart.
Problem
I have a generated string that contains the code for an erlang module. Is there a way to compile the generated module straight from the string? Or is there a way to convert the string into the format needed for `compile:forms/1`? Or will I have to save it to a temp file first and then compile it with `compile:file/1`? Alternatively, I can add support to the compile module, but there must be a reason why the good people that write erlang haven't added it.