# `Stamp.Config`
[🔗](https://github.com/a3kov/stamp/blob/main/lib/config.ex#L1)

Configuration structure for Stamp. Each stamp is generated and later
processed according to the configuration parameters.

# `t`

```elixir
@type t() :: %Stamp.Config{
  codec: atom() | nil,
  epoch: pos_integer(),
  node_bits: non_neg_integer(),
  node_fun: fun() | nil,
  partition_bits: non_neg_integer(),
  partition_fun: fun() | nil,
  prefix: String.t() | nil,
  sequence_bits: pos_integer(),
  time_bits: pos_integer()
}
```

# `new`

```elixir
@spec new(keyword()) :: t()
```

Create new Stamp config from options.
This function is also used internally to build config at compile time for Ecto IDs.
Using this function should be preferred over constructing `Stamp.Config` structs manually,
as it performs validation of the parameters.

Supported options:
  - `partition_bits` - number of bits reserved for partition number. 0 disables
    partitioning. Default is 0.

  - `time_bits` - positive number of bits reserved for time. Default is
    41.

  - `node_bits` - number of bits reserved for node number. 0 disables per-node-number
    sequences, which can be useful if the generator can't ever require more than 1 node.
    Default is 7.

  - `sequence_bits` - positive number of bits reserved for sequence. Default is
    15.

  - `node_fun` - 0-arity function returning current node number. The number must be unique
    across all BEAM nodes, and 1 number per BEAM node is enough (although it's not enforced).
    All Stamp configurations can share same node number. The number must fit in `node_bits`
    without overflow. Required with `node_bits` > 0. Default is nil (not set).

  - `partition_fun` - 0-arity function returning current partition. This works as a backchannel
    with `autogenerate: true` PK option in Ecto. Current partition for queries can be
    smuggled in via process dictionary or by other means. When generating IDs directly you can
    instead pass `partition` option to `Stamp.next_field_id/3` and `Stamp.next_id/3`. The
    number must fit in `partition_bits` without overflow. Required with `partition_bits` > 0.
    Default is nil (not set).

  - `epoch` - the number subtracted from the current unix time in milliseconds to
    compress it for storage. For permanently stored data the epoch must be chosen once and
    never changed later. Default is 1784842980000

  - `prefix` - a Stripe-style prefix to add to encoded IDs. For example, setting it to `foo_`
    will generate IDs that look like so: `foo_139546474327455` or `foo_ABdsdDggP`. If set,
    the prefix is always added and expected (values without it will trigger an error).
    Default is nil (disabled).

  - `codec` - a module implementing `Stamp.Codec` behaviour. When set, the library will encode
    the ID after generation/loading, so the final ID will be a string. The encoding must
    maintain lexicographic order for the IDs to have same sorting in string form. Required
    when prefix is set. Default is nil (disabled).

---

*Consult [api-reference.md](api-reference.md) for complete listing*