This repository was archived by the owner on May 23, 2019. It is now read-only.
-
Notifications
You must be signed in to change notification settings - Fork 1
/
Copy pathindex.html
748 lines (743 loc) · 35.3 KB
/
index.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
<!DOCTYPE html>
<html>
<head>
<title>Overcoming Our Obsession With Stringly-Typed Ruby</title>
<meta charset="utf-8">
<meta name="description" content="Overcoming Our Obsession With Stringly-Typed Ruby">
<meta name="viewport" content="width=device-width, initial-scale=1">
<script src="js/lib/jquery-1.8.0.min.js"></script>
<script src="js/lib/highlight-7.1.min.js"></script>
<script src="js/lib/jquerytypewriter.js"></script>
<script src="js/lib/underscore-1.3.3.min.js"></script>
<script src="js/lib/jquery.touchSwipe.min.js"></script>
<script src="js/utils.js"></script>
<script src="js/sizer.js"></script>
<script src="js/bullets.js"></script>
<script src="js/trickster.js"></script>
<script src="js/timer.js"></script>
<script src="js/custom.js"></script>
<link rel="stylesheet" href="css/normalize.css">
<link rel="stylesheet" href="css/theme.css">
<link rel="stylesheet" href="css/styles.css">
<script>
$(window).load(function() {
TricksterTimer = TricksterTimer(TricksterDefaultConfig,{});
TricksterTimer.setup();
Trickster = TricksterLoader(TricksterDefaultConfig,{});
Trickster.load(TricksterTimer);
});
</script>
<script src="//use.typekit.net/ief8bbd.js"></script>
<script>try{Typekit.load();}catch(e){}</script>
</head>
<body><div id="contents">
<section class='TITLE'>
<h1>Overcoming Our Obsession With Stringly-Typed Ruby</h1>
<h2>Dave Copeland · @davetron5000</h2>
<h3>http://www.naildrivin5.com · http://technology.stitchfix.com</h3>
</section>
<section class='IMAGE'>
<img src='images/cover.png'>
</section>
<section class='IMAGE'>
<img src='images/dccar2.jpg'>
</section>
<section class='TITLE'>
<h1>Overcoming Our Obsession With <br><i>Stringly-Typed</i> Ruby</h1>
</section>
<section class='SECTION'>
<h1>Stringly-Typed</h1>
<h2>From @codinghorror's “New Programmer Jargon”</h2>
<h3><a href="http://blog.codinghorror.com/new-programming-jargon/">http://blog.codinghorror.com/new-programming-jargon/</a></h3>
</section>
<section class='QUOTE'>
<h1>A riff on “strongly typed”. </h1>
<h2>Used to describe an implementation that needlessly relies on strings when programmer & refactor-friendly options are available.</h2>
</section>
<section class='SECTION'>
<h1>A tale of two zip codes</h1>
<h2>U.S. postal codes</h2>
<h3>aka "Zip Codes"</h3>
</section>
<section class='BULLETS'>
<h1>Zip Codes</h1>
<ul>
<li>Five Digits, e.g. 90210</li>
<li>Map to an area of the U.S.</li>
</ul>
</section>
<section class='IMAGE'>
<img src='images/zipcode_map.png'>
</section>
<section class='BULLETS'>
<h1>Simple App</h1>
<ul>
<li>Store addresses in a DB</li>
<li>Send letters to an address</li>
</ul>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='2,3,4'><span class='line line-1 ' >module ThirdPartyMailingService</span>
<div class='lines-callout'><span class='line line-2 line-callout' > def self.find_letter(letter_id)</span>
<span class='line line-3 line-callout' > # ...</span>
<span class='line line-4 line-callout' > end</span>
</div><span class='line line-5 ' ></span>
<span class='line line-6 ' > class Letter</span>
<span class='line line-7 ' > def mail!(street,city,state,zip_code)</span>
<span class='line line-8 ' > # ...</span>
<span class='line line-9 ' > end</span>
<span class='line line-10 ' > end</span>
<span class='line line-11 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='6,7,8,9,10'><span class='line line-1 ' >module ThirdPartyMailingService</span>
<span class='line line-2 ' > def self.find_letter(letter_id)</span>
<span class='line line-3 ' > # ...</span>
<span class='line line-4 ' > end</span>
<span class='line line-5 ' ></span>
<div class='lines-callout'><span class='line line-6 line-callout' > class Letter</span>
<span class='line line-7 line-callout' > def mail!(street,city,state,zip_code)</span>
<span class='line line-8 line-callout' > # ...</span>
<span class='line line-9 line-callout' > end</span>
<span class='line line-10 line-callout' > end</span>
</div><span class='line line-11 ' >end</span>
<span class='line line-12 ' ></span></code></pre>
</section>
<section class='CODE'>
<pre><code class='sql' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >create table addresses(</span>
<span class='line line-2 ' > id int not null,</span>
<span class='line line-3 ' > street varchar(256) not null,</span>
<span class='line line-4 ' > city varchar(256) not null,</span>
<span class='line line-5 ' > state char(2) not null,</span>
<span class='line line-6 ' > zip_code char(5) not null</span>
<span class='line line-7 ' >)</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='5,6'><span class='line line-1 ' >class AddressReader</span>
<span class='line line-2 ' > def read_new_address</span>
<span class='line line-3 ' > puts "Enter your address"</span>
<span class='line line-4 ' ></span>
<div class='lines-callout'><span class='line line-5 line-callout' > puts "street?"</span>
<span class='line line-6 line-callout' > street = gets</span>
</div><span class='line line-7 ' ></span>
<span class='line line-8 ' > puts "city?"</span>
<span class='line line-9 ' > city = gets</span>
<span class='line line-10 ' ></span>
<span class='line line-11 ' > puts "state?"</span>
<span class='line line-12 ' > state = gets</span>
<span class='line line-13 ' ></span>
<span class='line line-14 ' > puts "zip code?"</span>
<span class='line line-15 ' > zip_code = gets</span>
<span class='line line-16 ' ></span>
<span class='line line-17 ' > id = $database.insert_into(:addresses,</span>
<span class='line line-18 ' > street: street,</span>
<span class='line line-19 ' > city: city,</span>
<span class='line line-20 ' > state: state,</span>
<span class='line line-21 ' > zip_code: zip_code)</span>
<span class='line line-22 ' > </span>
<span class='line line-23 ' > puts "Created address #{id}"</span>
<span class='line line-24 ' > end</span>
<span class='line line-25 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='17,18,19,20,21'><span class='line line-1 ' >class AddressReader</span>
<span class='line line-2 ' > def read_new_address</span>
<span class='line line-3 ' > puts "Enter your address"</span>
<span class='line line-4 ' ></span>
<span class='line line-5 ' > puts "street?"</span>
<span class='line line-6 ' > street = gets</span>
<span class='line line-7 ' ></span>
<span class='line line-8 ' > puts "city?"</span>
<span class='line line-9 ' > city = gets</span>
<span class='line line-10 ' ></span>
<span class='line line-11 ' > puts "state?"</span>
<span class='line line-12 ' > state = gets</span>
<span class='line line-13 ' ></span>
<span class='line line-14 ' > puts "zip code?"</span>
<span class='line line-15 ' > zip_code = gets</span>
<span class='line line-16 ' ></span>
<div class='lines-callout'><span class='line line-17 line-callout' > id = $database.insert_into(:addresses,</span>
<span class='line line-18 line-callout' > street: street,</span>
<span class='line line-19 line-callout' > city: city,</span>
<span class='line line-20 line-callout' > state: state,</span>
<span class='line line-21 line-callout' > zip_code: zip_code)</span>
</div><span class='line line-22 ' > </span>
<span class='line line-23 ' > puts "Created address #{id}"</span>
<span class='line line-24 ' > end</span>
<span class='line line-25 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='3'><span class='line line-1 ' >class LetterSender</span>
<span class='line line-2 ' > def send_letter(letter_id,address_hash)</span>
<div class='lines-callout'><span class='line line-3 line-callout' > letter = ThirdPartyMailingService.find_letter(letter_id)</span>
</div><span class='line line-4 ' > letter.mail!(address_hash[:street],</span>
<span class='line line-5 ' > address_hash[:city],</span>
<span class='line line-6 ' > address_hash[:state],</span>
<span class='line line-7 ' > address_hash[:zip_code])</span>
<span class='line line-8 ' > end</span>
<span class='line line-9 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='4,5,6,7'><span class='line line-1 ' >class LetterSender</span>
<span class='line line-2 ' > def send_letter(letter_id,address_hash)</span>
<span class='line line-3 ' > letter = ThirdPartyMailingService.find_letter(letter_id)</span>
<div class='lines-callout'><span class='line line-4 line-callout' > letter.mail!(address_hash[:street],</span>
<span class='line line-5 line-callout' > address_hash[:city],</span>
<span class='line line-6 line-callout' > address_hash[:state],</span>
<span class='line line-7 line-callout' > address_hash[:zip_code])</span>
</div><span class='line line-8 ' > end</span>
<span class='line line-9 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='3,4'><span class='line line-1 ' >class Mailer</span>
<span class='line line-2 ' > def send_letter(address_id,letter_id)</span>
<div class='lines-callout'><span class='line line-3 line-callout' > address_hash = $database.select_from(:addresses,</span>
<span class='line line-4 line-callout' > :id => address_id)</span>
</div><span class='line line-5 ' > LetterSender.new.send_letter(letter_id, to: address_hash)</span>
<span class='line line-6 ' > puts "Letter ##{letter_id} sent to"</span>
<span class='line line-7 ' > puts address_hash[:street]</span>
<span class='line line-8 ' > puts "#{address_hash[:city], #{address_hash[:state]}, #{address_hash[:zip_code]}"</span>
<span class='line line-9 ' > end</span>
<span class='line line-10 ' >end</span>
<span class='line line-11 ' ></span>
<span class='line line-12 ' >Mailer.new.send_letter(ARGV[0].to_i, ARGV[1].to_i)</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='5'><span class='line line-1 ' >class Mailer</span>
<span class='line line-2 ' > def send_letter(address_id,letter_id)</span>
<span class='line line-3 ' > address_hash = $database.select_from(:addresses,</span>
<span class='line line-4 ' > :id => address_id)</span>
<div class='lines-callout'><span class='line line-5 line-callout' > LetterSender.new.send_letter(letter_id, to: address_hash)</span>
</div><span class='line line-6 ' > puts "Letter ##{letter_id} sent to"</span>
<span class='line line-7 ' > puts address_hash[:street]</span>
<span class='line line-8 ' > puts "#{address_hash[:city], #{address_hash[:state]}, #{address_hash[:zip_code]}"</span>
<span class='line line-9 ' > end</span>
<span class='line line-10 ' >end</span>
<span class='line line-11 ' ></span>
<span class='line line-12 ' >Mailer.new.send_letter(ARGV[0].to_i, ARGV[1].to_i)</span></code></pre>
</section>
<section class='COMMANDLINE'>
<pre><code class='no-highlight'><span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> ./store_address.rb</span>
<span class='cli-element cli-result'><span class='cli-line'>street?</span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> 45 S. Fair Oaks Ave</span>
<span class='cli-element cli-result'><span class='cli-line'>city?</span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> Beverley Hills</span>
<span class='cli-element cli-result'><span class='cli-line'>state?</span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> CA</span>
<span class='cli-element cli-result'><span class='cli-line'>zip?</span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> 90210</span>
<span class='cli-element cli-result'><span class='cli-line'>You created address 42</span></span>
</code></pre>
</section>
<section class='COMMANDLINE'>
<pre><code class='no-highlight'><span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> ./send_letter.rb 42 12</span>
<span class='cli-element cli-result'><span class='cli-line'>Letter #12 sent to</span>
<span class='cli-line'>45 S. Fair Oaks Ave</span>
<span class='cli-line'>Beverley Hills, CA 90210</span></span>
</code></pre>
</section>
<section class='COMMANDLINE'>
<pre><code class='no-highlight'><span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> ./store_address.rb</span>
<span class='cli-element cli-result'><span class='cli-line'>street?</span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> 1675 E Altadena Dr</span>
<span class='cli-element cli-result'><span class='cli-line'>city?</span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> Altadena</span>
<span class='cli-element cli-result'><span class='cli-line'>state?</span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> CA</span>
<span class='cli-element cli-result'><span class='cli-line'>zip?</span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> WALSH</span>
<span class='cli-element cli-result'><span class='cli-line'>You created address 43</span></span>
</code></pre>
</section>
<section class='COMMANDLINE'>
<pre><code class='no-highlight'><span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> ./send_letter.rb 43 12</span>
<span class='cli-element cli-result'><span class='cli-line'>Letter #12 sent to</span>
<span class='cli-line'>1675 E Altadena Dr</span>
<span class='cli-line'>Altadena, CA WALSH</span></span>
</code></pre>
</section>
<section class='NORMAL'>
<h1>Oops</h1>
</section>
<section class='NORMAL'>
<h1>Must be a problem reading input!</h1>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='3,4,5'><span class='line line-1 ' >zip_code = gets</span>
<span class='line line-2 ' ></span>
<div class='lines-callout'><span class='line line-3 line-callout' >unless zip_code =~ /^[0-9]{5}$/</span>
<span class='line line-4 line-callout' > raise "not a zip code" </span>
<span class='line line-5 line-callout' >end</span></div></code></pre>
</section>
<section class='CODE'>
<pre><code class='sql' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >INSERT INTO</span>
<span class='line line-2 ' > addresses(street,city,state,zip)</span>
<span class='line line-3 ' >VALUES</span>
<span class='line line-4 ' > ('1675 E Altadena Dr'</span>
<span class='line line-5 ' > 'Altadena',</span>
<span class='line line-6 ' > 'CA',</span>
<span class='line line-7 ' > 'WALSH')</span></code></pre>
</section>
<section class='NORMAL'>
<h1>Oh! Oh!</h1>
<h2>A problem in our database design!</h2>
</section>
<section class='CODE'>
<pre><code class='sql,' data-strikeouts='' data-callout-lines='5,6,7'><span class='line line-1 ' >ALTER TABLE</span>
<span class='line line-2 ' > addresses</span>
<span class='line line-3 ' >ADD CONSTRAINT</span>
<span class='line line-4 ' > looks_like_a_zipcode</span>
<div class='lines-callout'><span class='line line-5 line-callout' >CHECK (</span>
<span class='line line-6 line-callout' > (zip ~* '^[0-9]{5}$')</span>
<span class='line line-7 line-callout' >)</span></div></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >LetterSender.new.send_letter(letter_id,</span>
<span class='line line-2 ' > street: '1675 E Altadena Dr'</span>
<span class='line line-3 ' > city: 'Altadena',</span>
<span class='line line-4 ' > state: 'CA',</span>
<span class='line line-5 ' > zip_code: 'WALSH')</span></code></pre>
</section>
<section class='IMAGE'>
<img src='images/buzz.png'>
</section>
<section class='SECTION'>
<h1>This is not how to build a maintainable system</h1>
</section>
<section class='IMAGE'>
<img src='images/loose_boundaries.png'>
</section>
<section class='SECTION'>
<h1>Boundaries</h1>
</section>
<section class='NORMAL'>
<h1>What's coming and what's going</h1>
</section>
<section class='IMAGE'>
<img src='images/method.png'>
</section>
<section class='IMAGE'>
<img src='images/strings_and_hashes.png'>
</section>
<section class='SECTION'>
<h1>Data Types</h1>
</section>
<section class='BULLETS'>
<h1>Data Types</h1>
<ul>
<li>Possible Values</li>
<li>Allowed Operations</li>
<li>What they mean</li>
</ul>
</section>
<section class='FREEFORM'>
<table>
<thead>
<th></th>
<th>String</th>
<th>Zip Code</th>
</thead>
<tbody>
<tr>
<th>Possible values</th>
<td>Anything</td>
<td>Five Digits</td>
</tr>
<tr>
<th>Operations</th>
<td>A ton</td>
<td>Pretty much none</td>
</tr>
<tr>
<th>What They Mean</th>
<td>Anything</td>
<td>Location in the U.S.</td>
</tr>
</tbody>
</table>
</section>
<section class='IMAGE'>
<img src='images/strong_boundaries.png'>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >class ZipCode</span>
<span class='line line-2 ' > def initialize(string)</span>
<span class='line line-3 ' > @raw_zipcode = string</span>
<span class='line line-4 ' > end</span>
<span class='line line-5 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >class ZipCode</span>
<span class='line line-2 ' > def initialize(string)</span>
<span class='line line-3 ' > unless string =~ /^\d\d\d\d\d$/</span>
<span class='line line-4 ' > raise 'invalid zipcode' </span>
<span class='line line-5 ' > end</span>
<span class='line line-6 ' > @raw_zipcode = string</span>
<span class='line line-7 ' > end</span>
<span class='line line-8 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >zip1 = ZipCode.new("90210")</span>
<span class='line line-2 ' ></span>
<span class='line line-3 ' >zip2 = ZipCode.new("WALSH")</span>
<span class='line line-4 ' ># => boom</span>
<span class='line line-5 ' ># zip2 never gets assigned</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >class ZipCode</span>
<span class='line line-2 ' > def raw_zipcode</span>
<span class='line line-3 ' > @raw_zipcode</span>
<span class='line line-4 ' > end</span>
<span class='line line-5 ' >end</span></code></pre>
</section>
<section class='IMAGE'>
<img src='images/strong_boundaries.png'>
</section>
<section class='BULLETS'>
<h1>Design Activity</h1>
<ul>
<li>What problem am I solving?</li>
<li>Push code around to solve it</li>
<li>Define boundaries using data types</li>
</ul>
</section>
<section class='SECTION'>
<h1>How do we publicize these boundaries?</h1>
</section>
<section class='BULLETS'>
<h1>Conventions</h1>
<ul>
<li>Underscorize the classname, e.g. <code>zip_code</code></li>
<li>Suffix with underscorized, e.g. <code>sender_zip_code</code></li>
<li>Document public methods</li>
</ul>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >class FooBar</span>
<span class='line line-2 ' ></span>
<span class='line line-3 ' > # zip_code:: instance of ZipCode to geolocate</span>
<span class='line line-4 ' > def geolocate(zip_code)</span>
<span class='line line-5 ' > end</span>
<span class='line line-6 ' ></span>
<span class='line line-7 ' > # Returns a ZipCode nearest the given lat and long</span>
<span class='line line-8 ' > def nearest_zip_code(lat,long)</span>
<span class='line line-9 ' > end</span>
<span class='line line-10 ' ></span>
<span class='line line-11 ' >private</span>
<span class='line line-12 ' ></span>
<span class='line line-13 ' > def center_point(zip_code)</span>
<span class='line line-14 ' > end</span>
<span class='line line-15 ' >end</span></code></pre>
</section>
<section class='SECTION'>
<h1>Can we enforce this?</h1>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='3'><span class='line line-1 ' >class FooBar</span>
<span class='line line-2 ' > def geolocate(zip_code)</span>
<div class='lines-callout'><span class='line line-3 line-callout' > unless zip_code.is_a?(ZipCode)</span>
</div><span class='line line-4 ' > raise ArgumentError, "must be a ZipCode"</span>
<span class='line line-5 ' > end</span>
<span class='line line-6 ' > # ...</span>
<span class='line line-7 ' > end</span>
<span class='line line-8 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='3'><span class='line line-1 ' >class FooBar</span>
<span class='line line-2 ' > def geolocate(zip_code)</span>
<div class='lines-callout'><span class='line line-3 line-callout' > unless zip_code.instance_of?(ZipCode)</span>
</div><span class='line line-4 ' > raise ArgumentError, "must be a ZipCode"</span>
<span class='line line-5 ' > end</span>
<span class='line line-6 ' > # ...</span>
<span class='line line-7 ' > end</span>
<span class='line line-8 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='3'><span class='line line-1 ' >class FooBar</span>
<span class='line line-2 ' > def geolocate(zip_code)</span>
<div class='lines-callout'><span class='line line-3 line-callout' > unless zip_code.respond_to?(:raw_zipcode)</span>
</div><span class='line line-4 ' > raise ArgumentError, "must implement #raw_zipcode"</span>
<span class='line line-5 ' > end</span>
<span class='line line-6 ' > # ...</span>
<span class='line line-7 ' > end</span>
<span class='line line-8 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='4'><span class='line line-1 ' >class FooBarTest</span>
<span class='line line-2 ' > def test_that_we_get_the_right_data_type</span>
<span class='line line-3 ' > result = foo_bar.nearest_zip_code(lat,long)</span>
<div class='lines-callout'><span class='line line-4 line-callout' > assert result.is_a?(ZipCode), </span>
</div><span class='line line-5 ' > "Got a #{result.class} instead :("</span>
<span class='line line-6 ' > end</span>
<span class='line line-7 ' >end</span></code></pre>
</section>
<section class='SECTION'>
<h1><strong>Should</strong> we?</h1>
</section>
<section class='IMAGE'>
<img src='images/types_everywhere.png'>
</section>
<section class='IMAGE'>
<img src='images/scala-logo.png'>
</section>
<section class='BULLETS'>
<h1>Two Times You Might</h1>
<ul>
<li>Risk</li>
<li>Big Refactor</li>
</ul>
</section>
<section class='BULLETS'>
<h1>Risk</h1>
<ul>
<li>How often do we expect a bad type?</li>
<li>What happens if a one does?</li>
</ul>
</section>
<section class='BULLETS'>
<h1>Big Refactor (w/compiler)</h1>
<ul>
<li>Change core types as needed</li>
<li>Compile</li>
<li>Fix the errors</li>
</ul>
</section>
<section class='BULLETS'>
<h1>Big Refactor (no compiler)</h1>
<ul>
<li>Change core types as needed</li>
<li>Add explicit type checks</li>
<li>Run tests</li>
<li>Fix the errors</li>
<li>Remove explicit type checks</li>
</ul>
</section>
<section class='BULLETS'>
<h1>When The World Wants/Has Strings</h1>
<ul>
<li>Protocols - Data Type → String</li>
<li>Wrappers - String → Data Type</li>
</ul>
</section>
<section class='SECTION'>
<h1>Protocols</h1>
<h2><a href="http://www.confidentruby.com">www.confidentruby.com</a></h2>
<h3>Chapter 4.2</h3>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >class ZipCode</span>
<span class='line line-2 ' > def initialize(string)</span>
<span class='line line-3 ' > unless string =~ /^\d\d\d\d\d$/</span>
<span class='line line-4 ' > raise 'invalid zipcode' </span>
<span class='line line-5 ' > end</span>
<span class='line line-6 ' > @raw_zipcode = string</span>
<span class='line line-7 ' > end</span>
<span class='line line-8 ' ></span>
<span class='line line-9 ' > def raw_zipcode</span>
<span class='line line-10 ' > @raw_zipcode</span>
<span class='line line-11 ' > end</span>
<span class='line line-12 ' >end</span></code></pre>
</section>
<section class='COMMANDLINE'>
<pre><code class='no-highlight'><span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> zip = ZipCode.new("90210")</span>
<span class='cli-element cli-result'><span class='cli-line'><ZipCode:0x007fb02d8b0968 @raw_zipcode="90210"></span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> puts zip</span>
<span class='cli-element cli-result'><span class='cli-line'><ZipCode:0x007fb02d8b0968></span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> puts "The zip is #{zip}"</span>
<span class='cli-element cli-result'><span class='cli-line'>The zip is <ZipCode:0x007fb02d8b0968></span></span>
</code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >class ZipCode</span>
<span class='line line-2 ' > alias to_s raw_zipcode</span>
<span class='line line-3 ' >end</span></code></pre>
</section>
<section class='COMMANDLINE'>
<pre><code class='no-highlight'><span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> puts "The zip is #{zip}"</span>
<span class='cli-element cli-result'><span class='cli-line'>The zip is 90210</span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> puts "The zip is " + zip</span>
<span class='cli-element cli-result'><span class='cli-line'>TypeError: no implicit conversion of ZipCode into String</span>
<span class='cli-line'> from (irb):12:in `+'</span>
<span class='cli-line'> from (irb):12</span>
<span class='cli-line'> from /Users/davec/.rvm/rubies/ruby-2.1.0/bin/irb:11:in `<main>'</span></span>
</code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >class ZipCode</span>
<span class='line line-2 ' > alias to_str raw_zipcode</span>
<span class='line line-3 ' >end</span></code></pre>
</section>
<section class='COMMANDLINE'>
<pre><code class='no-highlight'><span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> puts "The zip is " + zip</span>
<span class='cli-element cli-result'><span class='cli-line'>The zip is 90210</span></span>
</code></pre>
</section>
<section class='CODE'>
<pre><code class='html' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' ><dt>ZipCode</dt></span>
<span class='line line-2 ' ><dd><%= zip_code %></dd></span></code></pre>
</section>
<section class='BULLETS'>
<h1>Non-String Goodies, too</h1>
<ul>
<li><code>to_a</code></li>
<li><code>to_int</code></li>
<li><code>to_h</code></li>
</ul>
</section>
<section class='SECTION'>
<h1>Wrappers</h1>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >class Mailer</span>
<span class='line line-2 ' > def send_letter(address_id,letter_id)</span>
<span class='line line-3 ' > address_hash = $database.select_from(:addresses,</span>
<span class='line line-4 ' > :id => address_id)</span>
<span class='line line-5 ' ></span>
<span class='line line-6 ' > LetterSender.new.send_letter(letter_id, to: address_hash)</span>
<span class='line line-7 ' > end</span>
<span class='line line-8 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby,' data-strikeouts='' data-callout-lines='3'><span class='line line-1 ' >class WrappingDatabase < SimpleDelegator</span>
<span class='line line-2 ' > def convert(table: table, column: column, to: type)</span>
<div class='lines-callout'><span class='line line-3 line-callout' > @conversions[table][column] = type</span>
</div><span class='line line-4 ' > end</span>
<span class='line line-5 ' >end</span>
<span class='line line-6 ' >$database = WrappingDatabase.new($database)</span>
<span class='line line-7 ' ></span>
<span class='line line-8 ' >$database.convert table: :addresses, </span>
<span class='line line-9 ' > column: :zip_code, </span>
<span class='line line-10 ' > to: ZipCode</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >class WrappingDatabase < SimpleDelegator</span>
<span class='line line-2 ' > def select_from(table, where)</span>
<span class='line line-3 ' > raw_results = __getobj__.select_from(table,where)</span>
<span class='line line-4 ' > convert_results(table,raw_results)</span>
<span class='line line-5 ' > end</span>
<span class='line line-6 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >def convert_results(table,raw_results)</span>
<span class='line line-2 ' > raw_results.map { |row_hash|</span>
<span class='line line-3 ' > convert_row(table,row_hash)</span>
<span class='line line-4 ' > }</span>
<span class='line line-5 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >def convert_row(table,row_hash)</span>
<span class='line line-2 ' > row_as_array = row_hash.map { |column,value|</span>
<span class='line line-3 ' > new_value = if @conversions[table][column]</span>
<span class='line line-4 ' > # e.g. ZipCode.new("90210")</span>
<span class='line line-5 ' > @conversions[table][column].new(value)</span>
<span class='line line-6 ' > else</span>
<span class='line line-7 ' > value</span>
<span class='line line-8 ' > end</span>
<span class='line line-9 ' > [column,new_value]</span>
<span class='line line-10 ' > }</span>
<span class='line line-11 ' > row_as_array.to_h</span>
<span class='line line-12 ' >end</span>
<span class='line line-13 ' ></span></code></pre>
</section>
<section class='NORMAL'>
<h1>Active Record</h1>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >class Address < ActiveRecord::Base</span>
<span class='line line-2 ' > serialize :zip_code, ZipCode</span>
<span class='line line-3 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >class ZipCode</span>
<span class='line line-2 ' > def self.load(raw_string)</span>
<span class='line line-3 ' > self.new(raw_string)</span>
<span class='line line-4 ' > end</span>
<span class='line line-5 ' ></span>
<span class='line line-6 ' > def self.dump(zip_code)</span>
<span class='line line-7 ' > zip_code.to_str</span>
<span class='line line-8 ' > end</span>
<span class='line line-9 ' >end</span></code></pre>
</section>
<section class='CODE'>
<pre><code class='none' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >address = Address.find(43) # has the bad zipcode</span>
<span class='line line-2 ' ><ArgumentError "must be a ZipCode"></span></code></pre>
</section>
<section class='NORMAL'>
<h1>Sequel</h1>
</section>
<section class='CODE'>
<pre><code class='ruby' data-strikeouts='' data-callout-lines=''><span class='line line-1 ' >require 'sequel/plugins/serialization'</span>
<span class='line line-2 ' >Sequel::Plugins::Serialization.register_format(:zip_code_serialization,</span>
<span class='line line-3 ' > ->(zip_code) { zip_code.to_str },</span>
<span class='line line-4 ' > ->(raw_string) { ZipCode.new(raw_string) }</span>
<span class='line line-5 ' >)</span>
<span class='line line-6 ' ></span>
<span class='line line-7 ' >class Address < Sequel::Model</span>
<span class='line line-8 ' > plugin :serialization</span>
<span class='line line-9 ' > serialize_attributes :zip_code_serialization, :zip_code</span>
<span class='line line-10 ' >end</span></code></pre>
</section>
<section class='SECTION'>
<h1>Other Opportunites</h1>
</section>
<section class='NORMAL'>
<h1>Email</h1>
<h2><code>EmailAddress</code>, <code>VerifiedEmailAddress</code></h2>
</section>
<section class='COMMANDLINE'>
<pre><code class='no-highlight'><span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> "[email protected]" == "[email protected]"</span>
<span class='cli-element cli-result'><span class='cli-line'> => false </span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> "[email protected]".downcase == "[email protected]".downcase #sigh</span>
<span class='cli-element cli-result'><span class='cli-line'> => true </span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> EmailAddress.new("[email protected]") == EmailAddress.new("[email protected]")</span>
<span class='cli-element cli-result'><span class='cli-line'> => true</span></span>
</code></pre>
</section>
<section class='NORMAL'>
<h1>Prices</h1>
</section>
<section class='COMMANDLINE'>
<pre><code class='no-highlight'><span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> third = Rational(1,3)</span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> (100 * third).to_f</span>
<span class='cli-element cli-result'><span class='cli-line'>33.333333333336</span></span>
<span class='cli-prompt'>></span> <span class='cli-element cli-command cli-line'> Price.new(100).discount(third) </span>
<span class='cli-element cli-result'><span class='cli-line'><Price value=33.33></span>
<span class='cli-line'></span></span>
</code></pre>
</section>
<section class='NORMAL'>
<h1>Enumerated Types</h1>
<h2>State/Province, Status Codes, Error Codes</h2>
</section>
<section class='SECTION'>
<h1>Use Data Types</h1>
<h2>Define Your Boundaries</h2>
<h3>Put Your Knowledge and Intent in Code</h3>
</section>
<section class='FREEFORM'>
<h1>THANKS!</h1>
<h2><a href="#">Slides</a></h2>
<h3><a href="http://www.naildrivin5.com/blog">My Blog - http://www.naildrivin5.com/blog</a></h3>
<h4><a href="http://technology.stitchfix.com/jobs">Get A New Job at http://technology.stitchfix.com/jobs</a></h4>
</section>
</div>
<aside id="timer">
<div id="clock">
<span class="hours">
<span id="hour">0</span> :
</span>
<span class="minutes">
<span id="minute">00</span>
</span>
<span class="seconds"> :
<span id="second">00</span>
</span>
</div>
<div id="controls">
<a id="stop" href="#" onclick="return TricksterTimer.stop();">◼</a>
<a id="play" href="#" onclick="return TricksterTimer.play();">▶</a>
<a id="pause" href="#" onclick="return TricksterTimer.pause();">▮▮</a>
</div>
</aside>
</body>
</html>