jeremy-w

Working Effectively with Legacy Code

Notes by Jeremy W. Sherman, October 2013, based on:

Feathers, Michael. Working Effectively with Legacy Code. Sixth printing, July 2007.

Foreword:

• Software systems degrade into a mess.
• Requirements ALWAYS change.
• Your goal as a software developer: Create designs that tolerate change.

jeremy-w

Modern Legacy Systems

Presented by Robert Annett at QCon London, 14 Sep 2012.

Notes by Jeremy W. Sherman, 2013–10–13.

“Legacy”

What is legacy?

• Often an insult, but how odd, not like that in normal English (cf. inheritance).
• Also perhaps defined as “as opposed to its alternatives, it’s the software that actually works”.

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Working Effectively with Legacy Code

Michael C. Feathers

Notes by Jeremy W. Sherman, 14 Oct 2013.

Chapter 11: I need to make a change. What methods should I test?

Use effect sketches to figure out where to target your characterization tests prior to making changes. Big fan-in means a big bang for your test-writing buck.

• Prior to changing, write characterization tests to pin down existing behavior.
• Characterization test: A test that characterizes the actual behavior of a piece of code (186).

jeremy-w

#!/bin/bash
#
# jira-prepare-commit-msg: Easy commit tagging for Jira
#
# https://gist.github.com/jeremy-w/818b2980f0d9768da83249458aa67678
#
# If you name your branch to include the Jira issue key,
# this hook will automatically add the issue key to your commit messages.
# This makes it easy to trace work back to Jira, and it also means
# your commits show up in the Activity tab for that issue.

jeremy-w

//clang++ -std=c++11 -stdlib=libc++ -framework Foundation nsarray.mm -o nsarray
/* Note:
 * - libstdc++ has been frozen by Apple at a pre-C++11 version, so you must opt
     for the newer, BSD-licensed libc++
 * - Apple clang 4.0 (based on LLVM 3.1svn) does not default to C++11 yet, so
     you must explicitly specify this language standard. */
/* @file nsarray.mm
 * @author Jeremy W. Sherman
 *
 * Demonstrates three different approaches to converting a std::vector

jeremy-w

//cc -Wextra -o build/dump-header-map dump-header-map.c
// see: https://github.com/llvm-mirror/clang/blob/release_40/include/clang/Lex/HeaderMapTypes.h
// https://github.com/llvm-mirror/clang/blob/release_40/include/clang/Lex/HeaderMap.h// https://github.com/llvm-mirror/clang/blob/release_40/lib/Lex/HeaderMap.cpp

// This is basically dump() from there.

#include <stdio.h>
#include <stdlib.h>
#include <sysexits.h>
#include <err.h>

jeremy-w

{
  "swagger": "2.0",
  "info": {
    "title": "Test swagger",
    "version": "0.1.0"
  },
  "definitions": {
    "File": {
      "title": "File",
      "type": "object",

jeremy-w

#!/usr/bin/env kotlinc -script --
/**
 @file named-match-repro.kts
 @author Jeremy W. Sherman (GitHub: @jeremy-w)

 Demo of some perplexing behavior.

 Questions:

 - Main question: How do I access a named capture group in a Kotlin script?

jeremy-w

class Parent: Error {
    var localizedDescription: String { "p" }
}
class Child: Parent {
    override var localizedDescription: String { "c" }
}
print("Given two error classes, Parent, and Child a kind of Parent\n")

let e: Result<Int, Child> = .failure(Child())
let e2: Result<Int, Parent>

jeremy-w

#! /usr/local/bin/tt++

/* Who wants to write out "inventory" in full? */
#alias {i} {inventory}
#alias {inv} {inventory}

/* Simpler AFK handling.
 * ifMUD has a 2-step AFK process.
 * This turns it into a one-step "afk MSG" process. */
#alias {afk} {@away me=%0}