all Python 3codecsfunction

codecs.register()

codec registry

Registers a codec search function: given a normalised name it returns a CodecInfo or None. This is how you add your own encoding to Python.

Syntax

codecs.register(search_function)

You register a search function, not a codec, and it must return None for names it does not own, or it hijacks every lookup. The name arrives lower-cased, so compare against 'shout', not 'Shout'. Results are cached: after the first successful lookup, changing your search function no longer affects that name; codecs.unregister (3.10+) removes it. For a coursework task a custom codec is almost never needed: str.translate or a plain function does the job.

Examples

import codecs
def search(name):
    if name == 'shout':
        enc = lambda s, errors='strict': (s.upper().encode(), len(s))
        dec = lambda b, errors='strict': (bytes(b).decode().lower(), len(b))
        return codecs.CodecInfo(enc, dec, name='shout')
    return None
codecs.register(search)
print('hi'.encode('Shout'))  # → b'HI'
print(b'HI'.decode('shout'))  # → hi

See also

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