[Python-Dev] New syntax for 'dynamic' attribute access (original) (raw)

Calvin Spealman ironfroggy at gmail.com
Mon Feb 12 20:31:32 CET 2007

I'll take this opportunity to pipe in with a response, since Guido summed up the many issues nicely and its a good bouncing point to mention my own thoughts.

On 2/12/07, Guido van Rossum <guido at python.org> wrote:

My perspective:

- There's a lot of support for the basic idea, and only a few naysayers, so let's keep looking for a syntax that works. - There's near-universal dislike for the two-arg form, so let's drop that part of the proposal. - I can't recall that x.[y] has been proposed yet, but thinking about it, that actually makes more sense than x.(y). (In fact, in JavaScript you can write x[y] to the same effect. I wouldn't discount the JS example; JS is probably closer to Python than almost any other language currently in existence except for Boo, and JS has successfully borrowed from Python.)

I'll second that. The JS case is valuable and a good representation of the mindset behind using foo.[bar]

- I'm not too concerned by the '.' being such a small character with this new proposal. x[y] is a lot less common than x(y), so you'll look twice when you think you see x[y] and it doesn't make sense, and then you'll notice it's really x.[y], which you either know or don't, and in the latter case you'll be looking it up or asking around.

I definitely see the downside of using the nearly invisible . here. Looking like dirt on the screen, being misunderstood, deleted because someone thought it was a typo, etc. could all be problems. I am not convinced they will be problems, only that they could.

Now, do we need a more readable attribute deference or is there some optimizational need to make a syntax specifically for it? Why can't we just wrap the object in question with some attribute lookup type?

attr(o)methodname vs o.methodname

I think if you read those two, at a quick glance the first is a lot more readable than the second. It also has the advantage of not modifying the language syntax, or introducing nearly as much new code.

-- Read my blog! I depend on your acceptance of my opinion! I am interesting! http://ironfroggy-code.blogspot.com/

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