id_coder

Id-codes are relatively short codes to represent externally id internal numbers.

A bijection between ids and codes is used to assure uniqueness of codes and to avoid storing the codes in the database (codes and ids are computed on-the-fly from each other).

Codes are user-visible; they’re designed to be the user’s identification of some element.

Only digits an capital letters are used for the codes, excluding I,O,1,0 to avoid confusion, and a check digit can be used to detect most common transcription errors. This makes codes viable to be transmitted orally, etc.

The number of digits used is scalable: the minimum number of digits and the increment-size can be parameterized to render good-looking codes.

An IdCoder can be defined passing to it three optional parameters that define the lenght of the codes:

IdCoder[:num_digits=>4, :block_digits=>3, :check_digit=>false]

An additional parameter can be passed to define which characters will be used as digits for the codes and its order; this must be a String of IdCoder::RADIX distinct characters:

IdCoder[:code_digits=>"0123456789ABCDEFGHIJKLMNOPQRSTUV"]

Alternatively, a seed parameter can be passed to generate a randomized string

IdCoder[:seed=>8734112]

Since this might produce different results in different Ruby versions, the code_digits produced can be accessed and kept for portability:

IdCoder[:seed=>8734112].code_digits # -> "9GTFNJSZA6LQWXV3BEKHYMP75U8R24CD"

Ids (integers) can be coded and decoded into alphanumeric strings like this:

id_coder = IdCoder[]
id_coder.id_to_code(7) # => "JEQJTE3"
id_coder.code_to_id("JEQJTE3") # => 7

id_coder

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