Yehuda Katz wycats

## errors.md

      
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                wycats
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              October 21, 2018 12:04
            
              
                How I think about error handling in Rust
              
          
Option: "None is a totally valid result, usually found in data structures"

unwrap(): YOLO use in prototyping
expect(...): to  indicate the reason you believe None is impossible (or a contract violation for the method)


Result: 😱 "Errors are unexpected but not bugs; the decision for how to handle them is up to the caller"

unwrap(): YOLO "I'm an app and don't know how to handle this error -- I'm fine if the whole process aborts"
try! / ?: "Leave the decision about how to handle this error to the caller; they have more information"
match / catch: "I'm going to handle the error right here right now"


panic!: ☠ "The error is a bug and can't be recovered from. Game over man. Rust is allowed to abort the process if it wants"


## C82p-0.rb
poem =
"My honeydew has flown from my hand
And my toast has gone to the
        moon.
But when I saw it on television,
Planting our flag on Halley's
        comet,
More still did I want to eat it.
"

## index.js
// require() some stuff from npm (like you were using browserify)
// and then hit Run Code to run it on the right
var fs = require("fs");

## gist:8b4579b9bbd63e145926
bash-4.3# ./dev-environment.sh
tune2fs 1.42.13 (17-May-2015)
Setting maximal mount count to -1
Setting interval between checks to 0 seconds
Creating journal inode: done
which: no distccd in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin)
distccd pid 25684 port 9256
WARNING: Image format was not specified for 'toolchain.sqf' and probing guessed raw.
         Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.
         Specify the 'raw' format explicitly to remove the restrictions.

## application.controller.js
import Ember from 'ember';

export default Ember.Controller.extend({
  appName:'Ember Twiddle'
});

## gist:d16b1c64b9f88169ad1c
module Mst

  def self.included(base)
    base.extend(ClassMethods)
  end

  module ClassMethods
    def before(method_name)
      m = instance_method(method_name)
      define_method method_name do |*args, &block|

## getter.js
class Person {
  @reader _first, _last;

  constructor(first, last) {
    this._first = first;
    this._last = last;
  }
}

class Person {

## controllers.application.js
export default Ember.Controller.extend({
  appName:'Ember Twiddle'
});

## gist:ee71e53b887855d1ae52
export default function ifHelper([value]) {
  if (value) {
    this.yield();
  }
}

## equivalence.js
class Parent extends Person {
  constructor() {
    super(arg1, arg2);

    // desugars to
    // InitializeThis(<activefunction>.__proto__.[[Construct]]([arg1, arg2], NewTarget);
  }

  someMethod() {
    // these are equivalent
	poem =
	"My honeydew has flown from my hand
	And my toast has gone to the
	moon.
	But when I saw it on television,
	Planting our flag on Halley's
	comet,
	More still did I want to eat it.
	"
	// require() some stuff from npm (like you were using browserify)
	// and then hit Run Code to run it on the right
	var fs = require("fs");
	bash-4.3# ./dev-environment.sh
	tune2fs 1.42.13 (17-May-2015)
	Setting maximal mount count to -1
	Setting interval between checks to 0 seconds
	Creating journal inode: done
	which: no distccd in (/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin)
	distccd pid 25684 port 9256
	WARNING: Image format was not specified for 'toolchain.sqf' and probing guessed raw.
	Automatically detecting the format is dangerous for raw images, write operations on block 0 will be restricted.
	Specify the 'raw' format explicitly to remove the restrictions.
	import Ember from 'ember';

	export default Ember.Controller.extend({
	appName:'Ember Twiddle'
	});
	module Mst

	def self.included(base)
	base.extend(ClassMethods)
	end

	module ClassMethods
	def before(method_name)
	m = instance_method(method_name)
	define_method method_name do \|*args, &block\|
	class Person {
	@reader _first, _last;

	constructor(first, last) {
	this._first = first;
	this._last = last;
	}
	}

	class Person {
	export default function ifHelper([value]) {
	if (value) {
	this.yield();
	}
	}
	class Parent extends Person {
	constructor() {
	super(arg1, arg2);

	// desugars to
	// InitializeThis(<activefunction>.__proto__.[[Construct]]([arg1, arg2], NewTarget);
	}

	someMethod() {
	// these are equivalent