On Oct 21, 2008, at 8:41 AM, mb wrote:
> I'd like to propose the following chimera of doto and ->.
>
> (defmacro doto->
> [obj & forms]
> (let [objx (gensym "obj__")]
> `(let [~objx ~obj]
> (do
> ~@(map (fn [f]
> (if (seq? f)
> `(~(first f) ~objx ~@(rest f))
> `(~f ~objx)))
> forms))
> ~objx)))
Is the ".." aspect of it the "automatically make a list if it's not
one" part?
Along the lines of your example, one could do:
(doto-> (JFrame. "Hello Frame")
(miglayout (JLabel. "Hello Label"))
.pack
(.setVisible true))
I like it!
It seems a key thing to remember here is that while this does return a
useful value, it's primarily a construct for side effects. We're
calling these Clojure functions because they're compositions of calls
that have side effects either on the state of obj or on the system as
a whole (e.g., showing a window). We're throwing away the values
produced by the individual calls. This is in contrast to "->" where
each call's result is consumed by the next function in the thread.
As for the name, this operation seems a lot more like "doto" than "->"
to me. One option is "doto" in a namespace other than "clojure".
Prefix and suffix "." are both reserved to Clojure, so "doto." is out.
"do-for-side-effects" seems slightly wordy. "goto" is considered
harmful. I think if it can't be "doto", "doto->" is a fine name.
Cheers,
--Steve
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