pcantrell

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pcantrell

# How can we harmonize the types of a Square class and a Rectangle class
# so that it's possible to write a rescale function that works on both?
#
# As we saw in class Wed, if we’re doing this in Java, inheritance cannot
# solve this problem in a simple way: both `Square extends Rectangle`
# and `Rectangle extends Square` end up violating the Liskov Substitution
# Principle. While there is a nice “is-a” relationship here — all squares
# are rectangles! — that does not translate nicely into Java’s type system.
#
# In class today, we saw that having one inherit from the other doesn’t

pcantrell

# ------ Base class with metaprogramming ------

# This might make more sense if you skip ahead to the 🦄🦄🦄🌈🌈🌈 first
# and study the desired results, then come back here.

class Animal
  def initialize(name)
    @name = name
  end

pcantrell

Turning programmer errors into type errors

An example problem

In Wordy, suppose that BinaryExpressionNode were designed like this, with the operator modeled as a string:

public class BinaryExpressionNode extends ExpressionNode {
    // Valid operator types include "addition", "subtraction", "multiplication",
 // "division", and "exponentiation". Other strings are not valid operators.

pcantrell

Swift Evolution proposals for the three features I covered:

• Dynamic Member Lookup
• Dynamic Callable
• Key Path Member Lookup

Here's a good (and mildly critical) overview of dynamic member lookup.

Python interop:

• Library to use Python with normal Swift
• Plotting library I used in tonight’s demo

pcantrell

import Foundation

// WHY HAVE A TIMER SYNCED TO DISPLAY REFRESH?
// 
// Sparked by this question from Nick Lockwood:
// https://twitter.com/nicklockwood/status/1131650052701786114

class TimerPhasingSimulation
    {
    // –––––– Heart of the simulation ––––––

pcantrell

Goals

• Create a standard way for devs to document what assumption led them to use an unsafe operation (e.g. force unwrap).
• Cover all trapping operations (!, try!, as!, []) through a single mechanism. (Lack of this seems to have been Lattner’s primary beef with the previous proposal.)
• Make this mechanism work as both:
  • developer documentation — clear, readable, and not excessively noisy in the code itself — and
  • runtime diagnostic, included in console / crash logs to expedite debugging.

Solution

pcantrell

1. Generalized existentials 😄 In progress!

   • Use case: implement Resource<T>, Siesta’s most obvious API design gap
   • Use case: silly dances like this

2. ✅ $0 ≠ all params

3. Fix anonymous closure argument goofiness (bug, older bug)

• Use case: I specifically made the more-frequently used closure arg the second one here so that code referencing only it as $1 would compile (where it would not if it were $0)

pcantrell

// Siesta’s Resource class represents the current “best information available”
// about a RESTful resource. Other parts of the code can observe changes to
// that state (started loading, received new data, received error, etc):

public protocol ResourceObserver
    {
    func resourceChanged(_ resource: Resource, event: ResourceEvent)
    // (plus other stuff I’m ignoring)
    }

pcantrell

What are the Rules for dating in the work place? Flirting?

What are the clear red lines?

Where does the line between work life and social life stop and start?

What mindset causes dating and flirting to be the first thing to come to mind when many men think about women in the workplace?

What can man do to professionalize their perception of women, and keep sexual obsession out of their work relationships?