[Email-SIG] [Python-Dev] Dropping bytes "support" in json

[Barry Warsaw]

On Apr 10, 2009, at 1:19 AM, glyph at divmod.com wrote:

> On 02:38 am, barry at python.org wrote:
>> So, what I'm really asking is this.  Let's say you agree that there  
>> are use cases for accessing a header value as either the raw  
>> encoded bytes or the decoded unicode.  What should this return:
>>
>> >>> message['Subject']
>>
>> The raw bytes or the decoded unicode?
>
> My personal preference would be to just get deprecate this API, and  
> get rid of it, replacing it with a slightly more explicit one.
>
>   message.headers['Subject']
>   message.bytes_headers['Subject']

This is pretty darn clever Glyph.  Stop that! :)

I'm not 100% sure I like the name .bytes_headers or that .headers  
should be the decoded header (rather than have .headers return the  
bytes thingie and say .decoded_headers return the decoded thingies),  
but I do like the general approach.

>> Now, setting headers.  Sometimes you have some unicode thing and  
>> sometimes you have some bytes.  You need to end up with bytes in  
>> the ASCII range and you'd like to leave the header value unencoded  
>> if so. But in both cases, you might have bytes or characters  
>> outside that range, so you need an explicit encoding, defaulting to  
>> utf-8 probably.
>
>   message.headers['Subject'] = 'Some text'
>
> should be equivalent to
>
>   message.headers['Subject'] = Header('Some text')

Yes, absolutely.  I think we're all in general agreement that header  
values should be instances of Header, or subclasses thereof.

> My preference would be that
>
>   message.headers['Subject'] = b'Some Bytes'
>
> would simply raise an exception.  If you've got some bytes, you  
> should instead do
>
>   message.bytes_headers['Subject'] = b'Some Bytes'
>
> or
>
>   message.headers['Subject'] = Header(bytes=b'Some Bytes',  
> encoding='utf-8')
>
> Explicit is better than implicit, right?

Yes.

Again, I really like the general idea, if I might quibble about some  
of the details.  Thanks for a great suggestion.

-Barry

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