[Email-SIG] API thoughts

[Barry Warsaw]

On Mar 07, 2011, at 09:06 PM, Steffen Daode Nurpmeso wrote:

>I find the interface a bit inconsistent in respect to 
>replace_header() (replaces the first header found), __delitem__() 
>(drops them all), __setitem__() (appends) in any case. 
>(I personally would through these __accessor__ things away, they 
>taste a bit strange when used to access email payload.)

I personally like this part of the API, and I think it's held up well under
years of use.  In general you don't care about header order, so using various
combinations of del, .get_all(), and __setitem__ work fine.  The semantics of
message-as-dict API, header ordering, the various header methods, etc. was
thought out and discussed, and I don't have a problem with them.

>And i would provide a series of functions which can be used 
>to get/set/modify header fields and bodies: 
>i would check wether the argument is a list and if, it would mean 
>"all bodies of a field".  This is of course very hard to implement 
>if it's done gracefully, i.e. with modification-detection, 
>order-preservation etc.
>
>Another, easier to implement, idea would be (yet) an(other) 
>iterator which supports in-place editing.  Perfect: it could yield 
>a (to be invented) class which offers methods like .field(), 
>.bodies() (all [bodies] - maybe even as sub-iterator), 
>.remove_field() etc...
>Doing it like this would offer the possibility to easily detect 
>in-place editing of header bodies etc...
>
>All of these are just suggestions and my very personal point of 
>view, of course. 
>But one thing is true, and that's that it is currently really hard 
>to remove or replace just one body of a field, especially if there 
>are multiple bodies for a field. 

Well, replace one header retaining original order is a bit difficult, but I've
rarely had to do that.  Still, it would probably make sense to add such
functionality -- *if* it can be done without complicating the API or the
implementation.  I think it could too, by adding an index argument to
.replace_header(), and using .get_all() to get an ordered list of the headers
of interest.

Cheers,
-Barry
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