How do I do this in Python 3 (string.join())?

[Chris Green]

Cameron Simpson <cs at cskk.id.au> wrote:
> On 26Aug2020 15:09, Chris Green <cl at isbd.net> wrote:
> >2QdxY4RzWzUUiLuE at potatochowder.com wrote:
> >> Join bytes objects with a byte object:
> >>
> >>     b"\n".join(popmsg[1])
> >
> >Aaahhh!  Thank you (and the other reply).
> 
> But note: joining bytes like strings is uncommon, and may indicate that 
> you should be working in strings to start with. Eg you may want to 
> convert popmsg from bytes to str and do a str.join anyway. It depends on 
> exactly what you're dealing with: are you doing text work, or are you 
> doing "binary data" work?
> 
> I know many network protocols are "bytes-as-text, but that is 
> accomplished by implying an encoding of the text, eg as ASCII, where 
> characters all fit in single bytes/octets.
> 
Yes, I realise that making everything a string before I start might be
the 'right' way to do things but one is a bit limited by what the mail
handling modules in Python provide.

E.g. in this case the only (well the only ready made) way to get a
POP3 message is using poplib and this just gives you a list of lines
made up of "bytes as text" :-

    popmsg = pop3.retr(i+1)

I join the lines to feed them into mailbox.mbox() to create a mbox I
can analyse and also a message which can be sent using SMTP.

Should I be converting to string somewhere?  I guess the POP3 and SMTP
libraries will cope with strings as input.  Can I convert to string
after the join for example?  If so, how?  Can I just do:-

    msgbytes = b'\n'.join(popmsg[1])
    msgstr = str(mshbytes)

(Yes, I know it can be one line, I was just being explicit).

... or do I need to stringify the lines returned by popmsg() before
joining them together?


Thank you for all your help and comments!

(I'm a C programmer at heart, preceded by being an assembler
programmer.  I started programming way back in the 1970s, I'm retired
now and Python is for relaxation (?) in my dotage)

-- 
Chris Green
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