Add addfields basic transformation

[mjumbewu]

I've found it handy a few times to be able to add a bunch of fields in one go. Adding multiple fields at once saves the transformations from having to copy each row to a new view more times than it needs to.

This patch uses an implementation that I put together, closely mirroring addfield. Thoughts?

[alimanfoo]

Hi @mjumbewu, this is really nice. I'd be happy to add this new function.

My only thought is that it would be more straightforward to just use tuples, rather than have the field function and the FieldDefinition class. Each of the tuples could be of length 2 (field name, value) or length 3 (field name, value, index). So the logic is then just to check the length of the tuple.

[mjumbewu]

@alimanfoo No problem. Also noting that the syntax def addfields(table, *fields, missing=None) breaks python2. I'm thinking of just changing it to def addfields(table, fields, missing=None), where fields is a collection of tuples, rather than moving the expansion to the end or just using *args, **kwargs.

[alimanfoo]

Sounds good to me.

…

On Sun, Mar 19, 2017 at 10:54 PM, Mjumbe Poe ***@***.***> wrote: @alimanfoo <https://github.com/alimanfoo> No problem. Also noting that the syntax def addfields(table, *fields, missing=None) breaks python2. I'm thinking of just changing it to def addfields(table, fields, missing=None), where fields is a collection of tuples, rather than moving the expansion to the end or just using *args, **kwargs. — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub <#417 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AAq8QospRZLuBAMHW4csB6PE76qFivd3ks5rnbIXgaJpZM4Mh3Tl> .

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[coveralls]

Coverage decreased (-1.2%) to 89.921% when pulling d62bf6c on mjumbewu:addfields into 4195e3f on petl-developers:master.

[alimanfoo]

Going ahead with merge, happy to revisit if any comments.