C3P0 contains protocol definitions.

Centralizing these definitions, it is hoped that libraries and applications will make use of them to make data more portable between components of a system.

This protocol standardizes finding an ID for a peice of data.

There are two functions in this protocol:

1. C3P0.ID.id(data)
2. C3P0.ID.guid(data)

By default the guid will fall back to the id.

This will work on all structs and maps which have fields id (and optionally guid)

To customize for your struct if there are different fields, derive the C3P0.ID protocol.

defmodule MyStruct do
  @derive {C3P0.ID, id_field: :local_id, guid_field: :global_id}
  defstruct [:local_id, :global_id]
end

The C3P0.Humanize protocol displays as a string the data provided.

Falls back to a simple to_string

The C3P0.Blank protocol deals with blankness.

Empty strings, bbinaries, lists, maps and tuples are considered blank? along with nil.

The protocol defines 3 functions:

• blank?(data) - true/false
• present?(data) - true/false
• presence(data) - returns the value if it is not blank. nil if it is blank

We love contributions and they're welcome here!

C3P0 is aiming to be a central collection of useful protocols and we'd love more protocols that folks find useful.

Please raise an issue or submit a PR. Protocols can be really powerful especially if everyone uses the same ones.

If available in Hex, the package can be installed by adding c3p0 to your list of dependencies in mix.exs:

def deps do
  [
    {:c3p0, "~> 0.1.0"}
  ]
end

Documentation can be generated with ExDoc and published on HexDocs. Once published, the docs can be found at https://hexdocs.pm/c3p0.