Overview

• Preliminaries.
  • Admin.
  • Upcoming Work.
  • Extra Credit.
  • Questions.
• A few Ruby-isms.
• HTML 5 structure.
• Work time.

Preliminaries

Admin

• Food!
• I saw interesting variation in the responses to "best Ruby resource", which I think reinforces my decision to use three different resources.
• How would you like to arrange our classes?
  • More class time for project work
  • More class time for discussion of readings
  • Other? (discussed first)
• Reminder: Alums here on Thursday!

Upcoming Work

• Any necessary prep work from chapter 6.
• Reading Journal for Wednesday (due Tuesday at 8pm)
  • Subject: Reading Journal for Class 8 (Your Name)
  • What do you see as the strengths and challenges of using CSS?
  • What do you see as the strengths and challenges of using Bootstrap?
  • What aspect of the chapter 5 reading confused you the most? Try to explain it in your own words.
• For Friday: SaaSBook 2 and 4.

Good Things to Do

Academic

• Monday, February 8, 4:15 p.m. in Bucksbaum 152, Miriam Langer enjoins you to "Do Your Work in Public" (part of the series "Digital in Public: Intellectual and Technical Skills for Making a Difference")
• Monday, February 8, 7:30-9:00, JRC 101: The Complex Relation Between Alcohol and Sexual Assault
• Noon Tuesday in the White PDR: Bowie, Mickey, and the NFL: Copyright in the 21st century (copies of the reading outside Sam's office)
• 7:30 pm Tuesday in ARH 131 - Funding for unfunded internships
• 4:15 p.m. Thursday in 3821: Life Beyond Grinnell, A Q&A With Awesome Alums
• After the CS Extra: ACM Chapter Meeting.
• Rosenfield Symposium on Campaign Finance.
• Anything in this week's Carnival and Creativity series
• Nora will be in 3819 9-10 p.m. Tuesday night to answer your questions
• Albert will be in 3819 9-10 p.m. Thursday night to answer your questions

Peer

• Home track meet on Saturday
• Vote for RJHB

Questions

A Few Ruby-isms

These are some reflections from your journals.

Ruby != Rails

In answering questions, many of you seemed to conflate Ruby and Rails. Ruby is a general-purpose programming language. Rails is a Web application development infrastructure that happens to use Ruby for its programming aspects.

Duck Typing (1)

"Type-less" Programming (0)

How do you deal with the issue that you haven't clearly specified the type of a variable or parameter?

Mixins (1)

Everything is an object, even Class and Object. (1)

What does that really mean?

Metaprogramming (4)

What is it and why is it useful?

Clearly, you don't need to know this well to survive in the class.
(Although you need to know some particular techniques.)

Generally, the idea that you can write programs that write code. Most frequent use in Ruby is for common object structures.

In Java

public class Course
{
  int number_registered;
  ...

  public int getNumberRegistered()
  {
    return number_registered;
  } // getNumberRegistered

  public static void setNumberRegistered(int nr)
  {
    number_registered = nr;
  } // setNumberRegistered
} // class Course

In Ruby, there are language constructs that let you say "I want a setter/getter for my field." (Reference manuals are your friend.) Metaprogramming lets you build one of these constructs yourself.

yield (3)

Another thing that's not absolutely essential, even though you see it used in the various template files.

Procedures can take blocks as input and then call those blocks at appropriate times. It's one of the ways in which Ruby provides too many mechanisms for the same basic idea.

def foo
  yield some_secret_code
end

foo { |code| screamAndShout unless validate code }

Operationally, we call foo, passing in the block `{ | code | ... }

When we hit the yield in foo, we evaluate the code in the block, using some_secret_code for code.

Symbols

Why do we bother?

Blank Methods (1)

class StaticPagesController < ApplicationController
  def home
  end

  def help
  end

  def about
  end
end

HTML 5 Structure

HTML 5 and the history of HTML.

Before the Web, there was SGML. We want info in digital format. We care about the content, we care about the layout, and we care about the role text plays. SGML provided ways to deal with this.

Then there was the Web. Share documents, marked up with tags that tell you a bit about roles and not so much about appearance. Some very basic tags (such as section headings, paragraphs, and lists).

Then the Web grew. How do I program it? Server side? Client side? Initial model: Shove an application in the middle of the page (Java Applets, Flash).

But how do we manipulate data on the page? A client-side page manipulation language, JavaScript. Over time, increased agreement on what should be in JavaScript, but still not perfect agreement. (Soon to be renamed ECMAScript because of the body that is arranging the agreement.)

The World Wide Web Consortium (aka W3C) designed CSS (Cascading Style Sheets) for describing appearance of Web documents. Allows us to separate role from appearance.

Now four technologies involved: HTML (for describing content and roles), Javascript (describes interactivity; real programming language); CSS (appearance); DOM (document object model; a better way to reprsent HTML for the Javascript). Together, these are HTML 5.

Work Time

Chapter 5!

Why isn't full_title working?

Because you didn't copy the appropriate code from chapter 4.