From: Koji Arai <JCA02266@...>
Date: 2001-03-17T09:01:17+09:00
Subject: [ruby-list:28815] Re: fgets

新井です。

In message "[ruby-list:28814] fgets"
  on 17 Mar 2001 08:20:34 +0900,
  Kazuhiro NISHIYAMA <zn@mbf.nifty.com> wrote:
> C言語のfgetsのようなサイズ制限付きのgetsをしようとすると
> 下のように少しずつ読み込んで自分でチェックするしか無いの
> でしょうか？

こういうのはどうですか？定義した fgets 以外のIO操作を使うとダメですが。

class IO
  def fgets(limit, rs = $/)
    return @save.slice!(0, limit) if @save and @save.size > 0

    s = gets(rs)
    if (s.nil? or s.size < limit)
      @save = nil
      s
    else
      @save = s
      s.slice!(0, limit)
    end
  end
end

open($0) {|f|
  while s = f.fgets(20)
    p s
  end
}

=>
"class IO\n"
"  def fgets(limit, r"
"s = $/)\n"
"    return @save.sli"
"ce!(0, limit) if @sa"
"ve and @save.size > "
"0\n"
"\n"
"    s = gets(rs)\n"
"    if (s.nil? or s."
"size < limit)\n"
"      @save = nil\n"
"      s\n"
"    else\n"
"      @save = s\n"
"      s.slice!(0, li"
"mit)\n"
"    end\n"
"  end\n"
"end\n"
"\n"
"open($0) {|f|\n"
"  while s = f.fgets("
"20)\n"
"    p s\n"
"  end\n"
"}\n"