_ [ruby] Symbol#to_proc 入門

うれしい場面を探ってみる。

>> class Symbol
>>   def to_proc
>>     Proc.new{|obj, *args| obj.__send__(self, *args)}
>>   end
>> end
>> a = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
>> sum = a.inject(0, &:+)
#=> 55
>> a.map!(&:to_s)
#=> ["1", "2", "3", "4", "5", "6", "7", "8", "9", "10"]
>> a.object_id
#=> -606102960
>> a.map(&:object_id)
#=> [-606126370, -606126410, -606126450, ...]
>> b = a.map(&:dup)
>> b.object_id
#=> -606133810
>> b.map(&:object_id)
#=> [-606133880, -606133920, -606133990, ...]

一次元だけ？

>> h = {"a" => "a", "b" => "b", "c" => "c"}
>> h.delete_if(&:==)
#=> {}

これぐらいかな。

>> h = {"controller" => "blog", "action" => "edit", "id" => 1234}
>> h.map(&:to_sym).inject({}, &:store)
#=> {:controller => "blog", :action => "edit", :id => 1234}

これはうそ。

Proc.new{|*args| args.shift.__send__(self, *args)}

だと、意図しない挙動をする方が多いかなぁ。

_ [ruby] Symbol#to_proc 入門 (2)

class Hash
  def symbolize_keys
    inject({}, &:_symbolize_keys)
  end

  def symbolize_keys!
    replace(symbolize_keys)
  end

  def stringify_keys
    inject({}, &:_stringify_keys)
  end

  def stringify_keys!
    replace(stringify_keys)
  end

  private

  def _symbolize_keys(pair)
    _convert_keys(pair, :to_sym)
  end

  def _stringify_keys(pair)
    _convert_keys(pair, :to_s)
  end

  def _convert_keys(pair, method)
    k, v = pair
    store(k.__send__(method), v)
    self
  end
end

ちょっとはすっきりしましたか？[N/n]

_ [javascript] cooool だけど、DRY じゃない

のは、自分なわけですが。 Log200603#2006-03-15 から。

<script type="text/javascript">
<!--
  var h2s = document.getElementsByTagName("h2");
  for(var i = 0, j = h2s.length; i < j; i++){
    var h2 = h2s[i];
    var textnode = h2.childNodes[0];
    var text = textnode.nodeValue;
    var date = text.split(" ")[0];
    h2.id = date;
    var anchor = document.createElement("a");
    anchor.name = date;
    anchor.appendChild(document.createTextNode(text));
    h2.replaceChild(anchor, textnode);
  }
//-->
</script>

<h2>2006-03-14 (Tue.)</h2>
#=> <h2 id="2006-03-14"><a name="2006-03-14">2006-03-14 (Tue.)</a></h2>

今はこんな感じのを忍ばせてもらってます。Opera とかで動くのかなぁ。