1 Convertible: Data-Conversion Protocol

(require file/convertible)

The file/convertible library provides a protocol to mediate between providers of data in different possible formats and consumers of the formats. For example, a datatype that implements prop:convertible might be able to convert itself to a GIF or PDF stream, in which case it would produce data for 'gif-bytes or 'pdf-bytes requests.

Any symbol can be used for a conversion request, but the following should be considered standard:

• 'text — a string for human-readable text

• 'gif-bytes — a byte string containing a GIF image encoding

• 'png-bytes — a byte string containing a PNG image encoding

• 'ps-bytes — a byte string containing a PostScript document

• 'eps-bytes — a byte string containing an Encapsulated PostScript document

• 'pdf-bytes — a byte string containing a PDF document

(convert v request [default]) → any

v : convertible?

request : symbol?

default : any/c = #f

Requests a data conversion from v, where request indicates the type of requested data and default is the value that the converter should return if it cannot produce data in the format indicated by request.