Seven Languages in Seven Weeks: Ruby, Day 2

custom_times.rb

class Integer
  def times
    1.upto(self) { yield }
  end
end

each_16.rb

arr = (1..16).to_a
arr.each { |i| print "#{i}#{i % 4 == 0 ? "\n" : ','}" }

each_slice_16.rb

arr = (1..16).to_a
arr.each_slice(4) { |slice| puts slice.join(", ") }

Grep.java

import java.io.BufferedReader;
import java.io.File;
import java.io.FileReader;
import java.io.IOException;
import java.util.regex.Pattern;
import java.util.regex.Matcher;

/**
 * Usage: java Grep <regular_expression> <file_name>
 */
public class Grep {
  public static void main(String[] args) throws IOException {
    Pattern pattern = Pattern.compile(args[0]);
    BufferedReader br = null;
    String line = null;
    int lineNumber = 1;
    
    try {
      br = new BufferedReader(new FileReader(new File(args[1])));
      while((line = br.readLine()) != null) {
        Matcher matcher = pattern.matcher(line);
        if (matcher.find()) {
          System.out.println(lineNumber + ": " + line);
        }
        lineNumber++;
      }    
    } finally {
      if (br != null) {
        br.close();
      }
    }
  }
}

grep.rb

# Usage: ruby grep.rb <regular_expression> <file_name>

IO.readlines(ARGV[1]).each_with_index{ |line, index| puts "#{index + 1}: #{line}" if line =~ /#{ARGV[0]}/}

SpringTransaction.java

return _transactionManager.execute(new VoidDBExecCallback() {
  public void doExecute(DBExecContext dbExecContext) throws TransactionException {
    dbExecContext.getJdbcTemplate().execute(
      "Select name from tbl_foo where id = ?", 
      new PreparedStatementSetter() {
        public void setValues(PreparedStatement ps) throws SQLException
        {
          ps.setInt(1, 12345);
        }
      }, 
      new RowCallbackHandler() {
        public void processRow(ResultSet rs) throws SQLException
        {
          String name = rs.getString(1);
        }
      }
    );
  }
});

transaction.rb

within_a_transaction { do_something }

within_a_transaction do
  do_something
  do_something_else
  do_a_third_thing
end

transaction_wrapper.rb

def within_a_transaction
  start_transaction
  yield
  end_transaction
end

tree_new.rb

class Tree
  attr_accessor :children, :node_name
  
  def initialize(tree = {})
    @node_name = tree.keys[0]
    @children = tree[@node_name].collect{ |k, v| Tree.new({k => v}) }
  end
  
  def visit_all(&block)
    visit &block
    children.each { |c| c.visit_all &block }
  end
  
  def visit(&block)
    block.call self
  end
end

tree = Tree.new({"grandpa" => {"dad" => {"child1" => {}, "child2" => {}}, "uncle" => {"child3" => {}, "child4" => {}}}})
tree.visit_all { |node| puts node.node_name }

tree_original.rb

class Tree
  attr_accessor :children, :node_name
  
  def initialize(name, children = [])
    @children = children
    @node_name = name
  end
  
  def visit_all(&block)
    visit &block
    children.each { |c| c.visit_all &block }
  end
  
  def visit(&block)
    block.call self
  end
end

tree = Tree.new("Ruby", [Tree.new("Reia"), Tree.new("MacRuby")])
tree.visit_all { |node| puts node.node_name }

See Seven Languages in Seven Weeks: Ruby, Day 2 for more information.