On Tue, Apr 26, 2011 at 8:26 PM, Hugo Duncan <duncan.h...@gmail.com> wrote:
>
> Inspired by a discussion [1] on supporting shFlags in stevedore, I drafted
> a defnkw [2] that allows for the following syntax:
>
> (defnkw foo
> "My foo"
> [positional1 … positionalN
> & [[kw1 description1 default1]
> [kw2 description2]]]
> …)
>
....
> The formatting of the generated doc string can obviously be improved, and
> it is not obvious to me what syntax to use for naming the keyword option map
> (:as). This approach would allow defaulted values to be merged back into the
> option map. Support for presence flags would require an extra element in
> the specification vector (e.g. [description default flag?])
> An alternative would be to use a more defnk like syntax:
>
> (defnkw foo
> "My foo"
> [positional1 … positionalN
> & :kw1 [description1 default1]
> :kw2 description2]
> …)
>
>
Here's an interesting alternative:
(defnkw foo
"My foo"
[positional1 ... positionalN
& {:kw1 {:doc "The kw1 argument"
:default default1}
:kw2 {:doc "Another"
:default blah
:as wheee}
:kw2 {}} :as options]
We can specify an :as key on the entire option map.
Maps are more flexible than vectors for attributes. :doc, :default, :as are
fairly descriptive
and other attributes can easily be added. There would be defaults for each
key.
I've put a spin on the CL defun shortcut for renaming keyword args (:kw2
will be bound to wheee).
See "Keyword Parameters": http://www.gigamonkeys.com/book/functions.html
This is an alternative which is much closer to CL's method:
& {[:kw2 wheee] {... atrs.. ]}
On the whole it seems pretty readable, but may be misleading with the { }
syntax.
It's also markedly more verbose.
> I would be interested in any comments.
>
>
> [1] https://github.com/pallet/stevedore/pull/1
> [2]
> https://github.com/pallet/common/blob/feature%2Fdefn-for-kw-args/src/pallet/common/core.clj
> --
> Hugo Duncan
>
>
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