ISBN with hyphens

[dazza-codes]

For an ISBN [1], can the extractor return a value that retains the hyphens?

Given the variable length of ISBN parts, it's not possible to reconstruct the hyphens or spaces once they are removed. It's desirable to validate and extract an ISBN while retaining the spaces or hyphens in it.

Identifiers::ISBN.extract '978-92-95055-02-5'
=> ["9789295055025"]

• [1] https://www.isbn-international.org/content/what-isbn

[dazza-codes]

It seems the hyphens are extracted by the gsub in

• https://github.com/altmetric/identifiers/blob/master/lib/identifiers/isbn.rb#L49
• https://github.com/altmetric/identifiers/blob/master/lib/identifiers/isbn.rb#L57

It seems impossible to replace them to reconstruct an ISBN with them once they are gone. If the extract method could take an optional argument to retain them, that could be good.