Feature or enhancement

According to RFC 4648, section 3.1:

Implementations MUST NOT add line feeds to base-encoded data unless
the specification referring to this document explicitly directs base
encoders to add line feeds after a specific number of characters.

But many specifications use Base 64 separated on lines of fixed length. The stdlib code contains multiple functions that take the Base 64 data and split it on multiple lines. It is worth to add a special support of this in the base functions that encode to Base 64 -- to improve maintenability (there is a known bug in email.base64mime.body_encode()), convenience and performance.

I choose name wrapcol for the parameter because it is already used in base64.a85encode(). Other (mostly private) functions that implement the Base 64 wrapping use different names: maxlinelen, maxlen, max_line_length. PR #102753 propose name width for binascii.b2a_ascii85() (it is also used in textwrap). So there is no consistency or single dominant option, but I am open for suggestions.

Linked PRs

• gh-143214: Add the wrapcol parameter in binascii.b2a_base64() and base64.b64encode() #143216