On Mon, Feb 2, 2009 at 6:34 AM, wubbie <[email protected]> wrote:
>
> any concrete example?
Here's an example of how -> makes it easy to get data out of nested maps.
(def person {
:name "Mark Volkmann"
:address {
:street "644 Glen Summit"
:city "St. Charles"
:state "Missouri"
:zip 63304}
:employer {
:name "Object Computing, Inc."
:address {
:street "12140 Woodcrest Executive Drive, Suite 250"
:city "Creve Coeur"
:state "Missouri"
:zip 63141}}})
(-> person :employer :address :city) ; returns "Creve Coeur"
Here's an example of how using doto with Swing is handy.
(ns com.ociweb.swing
(:import
(java.awt BorderLayout)
(java.awt.event ActionListener)
(javax.swing JButton JFrame JLabel JOptionPane JPanel JTextField)))
(defn message [text-field]
(str "Hello, " (.getText text-field) "!"))
(let [name-field (JTextField. "World" 10)
panel (JPanel.)
greet-button (JButton. "Greet")
frame (proxy [JFrame ActionListener]
[] ; superclass constructor arguments
(actionPerformed [e]
(JOptionPane/showMessageDialog nil (message name-field))))]
(doto panel
(.add (JLabel. "Name:"))
(.add name-field))
(doto frame
(.add panel BorderLayout/CENTER)
(.add greet-button BorderLayout/SOUTH)
(.pack)
(.setDefaultCloseOperation JFrame/EXIT_ON_CLOSE)
(.setVisible true))
(.addActionListener greet-button frame))
> On Feb 2, 5:13 am, Christian Vest Hansen <[email protected]> wrote:
>> On Sun, Feb 1, 2009 at 9:35 PM, e <[email protected]> wrote:
>> > This may be obvious to others, but what's the motivation behind it? Is it
>> > that we are very concerned about combatting the criticism that lisp has too
>> > many parens?
>>
>> The -> macro is simply an excellent tool for drilling into nested
>> structures and/or piping some value through a list of methods and
>> functions.
>>
>> It works very well indeed when mixed with doto - especially if you
>> have to work with Swing or other component'ish frameworks.
>>
>> > On Sun, Feb 1, 2009 at 3:09 PM, kkw <[email protected]> wrote:
>>
>> >> Hi sun,
>>
>> >> I thought this question looked familiar. I found some answers here
>> >> also:
>>
>> >>http://groups.google.com/group/clojure/browse_thread/thread/1f21663ea...
>>
>> >> Kev
>>
>> >> On Feb 2, 2:29 am, Adrian Cuthbertson <[email protected]>
>> >> wrote:
>> >> > Sorry! That should have read;
>> >> > (-> m :one :b)
>> >> > 2
>>
>> >> > On Sun, Feb 1, 2009 at 5:13 PM, e <[email protected]> wrote:
>> >> > > I was able to work through the first two examples, and thanks for
>> >> > > those. I
>> >> > > will have to study maps more, I guess, to understand the last one. I
>> >> > > don't
>> >> > > know where 'x' came from:
>>
>> >> > >> user=> (-> x :one :b)
>> >> > >> 2- Hide quoted text -
--
R. Mark Volkmann
Object Computing, Inc.
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