CODEWITHSUNDEEP
elixir
iconoclast
iconoclast

Reputation: 22610

In Elixir, is there any way to get a module to list its functions?

In the same way that we can get any object (or class) in Ruby to list its methods, is there any function in Elixir to list all functions belonging to a module? Something (at least remotely) like String.functions (where String could be replaced by any other module name)?

Upvotes: 76

Views: 25624

Answers (4)

softcode
softcode

Reputation: 4638

Not a function but a way to get module to list its functions in iex is to write the name of the module followed by . then hiting tab:

iex(1)> IO.     ## Hit tab
ANSI                    Stream                  StreamError
binread/1               binread/2               binstream/2
binwrite/1              binwrite/2              chardata_to_string/1
getn/1                  getn/2                  getn/3
gets/1                  gets/2                  inspect/1
inspect/2               inspect/3               iodata_length/1
iodata_to_binary/1      puts/1                  puts/2
read/1                  read/2                  stream/2
warn/1                  warn/2                  write/1
write/2

Upvotes: 4

Steven Schobert
Steven Schobert

Reputation: 4269

Each module in Elixir defines an __info__ function you can call to get information about that module.

According the Elixir Docs, 1.6.6 e.g., you can pass it :functions to get a list of functions that module contains.

Map.__info__(:functions)

[delete: 2, drop: 2, equal?: 2, fetch: 2, fetch!: 2, from_struct: 1, get: 2,
 get: 3, has_key?: 2, keys: 1, merge: 2, merge: 3, new: 0, pop: 2, pop: 3,
 put: 3, put_new: 3, size: 1, split: 2, take: 2, to_list: 1, update: 4,
 update!: 3, values: 1]

Upvotes: 108

sheepgobeep
sheepgobeep

Reputation: 783

I've been using iex(1)> exports TargetModuleName. It lists all functions and macros belonging to a module. I stumbled onto it trying to figure out how to stop Map.__info__(:functions) from truncating a long function list.

Upvotes: 19

Fred the Magic Wonder Dog
Fred the Magic Wonder Dog

Reputation: 9099

Since Elixir is also Erlang, there is an Erlang way to do this as well.

Every Elixir and Erlang module has the function module_info defined at compile time. There are two arities of this function. For example: 

iex(1)> Atom.module_info
 [module: Atom,
 exports: [__info__: 1, to_string: 1, to_char_list: 1, module_info: 0,
 module_info: 1], attributes: [vsn:       [66271031909514292894123295368320335064]],
 compile: [options: [:debug_info], version: '6.0.1',
 time: {2015, 9, 29, 2, 34, 37},
 source: '/private/tmp/elixir20150928-10892-fvin6a/elixir-1.1.1/lib/elixir/lib/atom.ex'],
 native: false,
 md5: <<49, 219, 86, 35, 141, 153, 70, 174, 245, 100, 68, 5, 62, 231, 60, 216>>]

You can specify a specific attribute to return. 

 iex(2)> Atom.module_info(:exports)
  [__info__: 1, to_string: 1, to_char_list: 1, module_info: 0, module_info: 1]

Erlang function verison: 

iex(3)> :crypto.module_info(:exports)
 [version: 0, stop: 0, supports: 0, info_lib: 0, hash: 2, hash_init: 1,
 hash_update: 2, hash_final: 1, hmac: 3, hmac: 4, hmac_init: 2, hmac_update: 2,
 hmac_final: 1, hmac_final_n: 2, block_encrypt: 4, block_encrypt: 3,
 block_decrypt: 3, next_iv: 2, next_iv: 3, stream_init: 3, stream_init: 2,
 stream_encrypt: 2, stream_decrypt: 2, rand_bytes: 1, strong_rand_bytes: 1,
 rand_bytes: 3, rand_uniform: 2, rand_seed: 1, mod_pow: 3, verify: 5, sign: 4,
 public_encrypt: 4, private_decrypt: 4, private_encrypt: 4, public_decrypt: 4,
 exor: 2, generate_key: 2, generate_key: 3, compute_key: 4, md5: 1, md5_init: 0,
 md5_update: 2, md5_final: 1, md4: 1, md4_init: 0, md4_update: 2, md4_final: 1,
 sha: 1, sha_init: 0, sha_update: 2, ...]

This is what the IEx autocomplete function uses that allows you to expand both Elixir and Erlang functions.

Upvotes: 45

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