WEBVTT 1 00:00:00.120 --> 00:00:05.400 Imagine having like a secret guy to navigate complex technical info, right, 2 00:00:05.719 --> 00:00:08.039 something that just pulls out the coolest facts, the most 3 00:00:08.119 --> 00:00:10.800 useful insights, and keeps you hooked the whole time. 4 00:00:10.919 --> 00:00:13.119 That's pretty much what we're doing today, exactly. 5 00:00:13.640 --> 00:00:14.919 This is the deep dive. 6 00:00:14.800 --> 00:00:18.359 We're embarking on, a well a deep dive into the 7 00:00:18.359 --> 00:00:21.879 world of Ruby programming. And our main source today is 8 00:00:22.199 --> 00:00:26.879 The Ruby Way Solutions and Techniques in Ruby Programming, the 9 00:00:27.000 --> 00:00:31.039 third Edition by Mark Bates. It's a fantastic resource. 10 00:00:30.679 --> 00:00:33.000 Yeah, it really is. And our mission really is to 11 00:00:33.039 --> 00:00:36.600 pull out those vital nuggets, those genuinely surprising facts from 12 00:00:36.679 --> 00:00:38.640 this guide. We want to give you a shortcut, you know, 13 00:00:39.119 --> 00:00:42.320 help you understand what makes Ruby tick, what makes it 14 00:00:42.399 --> 00:00:45.520 so powerful and unique, without getting totally bogged down in 15 00:00:45.560 --> 00:00:46.439 every last detail. 16 00:00:46.679 --> 00:00:48.679 Right. And it's important to say this isn't really a 17 00:00:48.719 --> 00:00:52.600 beginner's tutorial, No, definitely not. It's more of an outstanding reference, 18 00:00:52.759 --> 00:00:55.200 useful whether you're just starting to explore Ruby or you've 19 00:00:55.200 --> 00:00:56.200 been using it for years. 20 00:00:56.320 --> 00:00:58.359 Mark Bits makes this great point in the book. He says, 21 00:00:58.399 --> 00:01:01.359 the Ruby Way isn't just code, it's the whole philosophy 22 00:01:01.679 --> 00:01:06.079 embraced by Ruby's creator, mats and the community exactly. 23 00:01:06.120 --> 00:01:09.680 It's this living, evolving culture that goes way beyond just 24 00:01:09.760 --> 00:01:10.640 syntax rules. 25 00:01:10.760 --> 00:01:14.400 Yeah, that ineffable spirit. He talks about the roller coaster ride. Yeah, 26 00:01:14.439 --> 00:01:17.760 it sounds really compelling. So what's one aspect of Ruby's 27 00:01:17.760 --> 00:01:21.400 philosophy for you that really captures that feeling? Maybe something 28 00:01:21.400 --> 00:01:22.760 that gave you inn aha moment? 29 00:01:22.840 --> 00:01:26.400 Oh uh? For me, it's got to be the principle 30 00:01:26.400 --> 00:01:30.719 of least surprise POLS as people often call it POLS. Okay, 31 00:01:31.159 --> 00:01:36.120 it's this core idea that the language should just work 32 00:01:36.200 --> 00:01:40.200 the way you expect it to. It tries to be intuitive, predictable, 33 00:01:40.319 --> 00:01:42.400 reducing those moments where you're like, wait, why did it 34 00:01:42.480 --> 00:01:45.400 do that? And there's even that playful counter acronym some 35 00:01:45.480 --> 00:01:51.079 Rubists to usela lola least object oriented annoyance. It's kind 36 00:01:51.120 --> 00:01:54.400 of a nod to preferring practical design, you know, over 37 00:01:54.480 --> 00:01:57.599 super rigid op rules sometimes making sure stuff doesn't just 38 00:01:57.680 --> 00:01:58.239 get in your way. 39 00:01:58.439 --> 00:02:01.400 Least object oriented annoyance. Like that that really sets a tone, 40 00:02:01.400 --> 00:02:03.599 doesn't it. So? Okay, when you're talking to developers, maybe 41 00:02:03.599 --> 00:02:06.159 they're building libraries or UIs, how does this principle of 42 00:02:06.200 --> 00:02:08.439 lease surprise actually show up in the code like a 43 00:02:08.439 --> 00:02:09.400 concrete example. 44 00:02:09.560 --> 00:02:13.199 Sure, well, think about method names or how common operations work. 45 00:02:13.599 --> 00:02:17.319 If you expect a method like say chomp to actually 46 00:02:17.439 --> 00:02:18.639 change the string it's. 47 00:02:18.439 --> 00:02:20.599 Called on right, modify it in place. 48 00:02:20.400 --> 00:02:23.680 Exactly it does. If you expect arithmetic operators to behave 49 00:02:23.719 --> 00:02:27.159 normally they do. It just leads to fewer surprises, less 50 00:02:27.159 --> 00:02:30.520 time digging through docs for basic stuff. It really builds 51 00:02:30.560 --> 00:02:33.240 trust in the language. You feel like it's working with you. 52 00:02:33.639 --> 00:02:36.719 That makes a lot of sense. Okay, moving into Ruby 53 00:02:36.800 --> 00:02:40.520 syntax and semantics, it's unique flavor. I've heard the parser 54 00:02:40.639 --> 00:02:45.759 described as complex but also relatively forgiving. What's that mean 55 00:02:45.840 --> 00:02:47.000 for someone writing Ruby? 56 00:02:47.319 --> 00:02:50.960 It means Ruby tries quite hard to understand what you 57 00:02:51.039 --> 00:02:53.560 meant to write, even if it's maybe a bit ambiguous. 58 00:02:53.599 --> 00:02:55.599 It doesn't just throw up its hands at the first 59 00:02:55.639 --> 00:02:58.360 sign of trouble like some stricter parsers might write. 60 00:02:58.400 --> 00:03:00.400 It gives you a bit of leeway exactly. 61 00:03:00.080 --> 00:03:03.400 Which can be really convenient. Let's express things more naturally sometimes. 62 00:03:03.560 --> 00:03:06.639 Okay, now here's a classic Ruby quirk, something that often 63 00:03:06.680 --> 00:03:10.080 trips people up coming from other languages. Truthiness. Can you 64 00:03:10.240 --> 00:03:10.919 walk us through that? 65 00:03:11.240 --> 00:03:13.719 Yeah, This is a big one. In Ruby, only two 66 00:03:13.840 --> 00:03:17.560 things are considered false in a boolean context, the special 67 00:03:17.639 --> 00:03:20.520 value nil and the boolean false itself. 68 00:03:21.080 --> 00:03:22.360 Those two, Just those two. 69 00:03:22.520 --> 00:03:25.719 Everything else, and I mean everything, an empty string, the 70 00:03:25.800 --> 00:03:28.520 numbers are away, an empty array, empty hash. All of 71 00:03:28.560 --> 00:03:30.000 it evaluates to true. 72 00:03:30.080 --> 00:03:34.039 Wow. Okay, so zero isn't false like in C or JavaScript. 73 00:03:34.199 --> 00:03:37.280 Nope. That's a common gotcha definitely, But once you get 74 00:03:37.360 --> 00:03:40.000 used to it, it actually simplifies a lot of conditional logic. 75 00:03:40.120 --> 00:03:43.159 You don't need explicit checks for nil or false all 76 00:03:43.199 --> 00:03:43.520 the time. 77 00:03:43.680 --> 00:03:46.759 Good to know. What about that convention of methods ending 78 00:03:46.759 --> 00:03:49.400 with an exclamation point like chomp? 79 00:03:49.639 --> 00:03:51.759 The book calls them dangerous. 80 00:03:51.240 --> 00:03:54.080 Right, the bang methods The thing is a strong visual cue. 81 00:03:54.199 --> 00:03:56.919 It's a warning sign basically warning Yeah. It signals that 82 00:03:56.960 --> 00:04:00.560 the method modifies the object it's called on directly in place, 83 00:04:00.879 --> 00:04:04.039 instead of returning a new modified version. It has a 84 00:04:04.080 --> 00:04:06.879 side effect, as they say, so, string dot chomp gives 85 00:04:06.879 --> 00:04:09.080 you a new string without the new line. But string 86 00:04:09.120 --> 00:04:11.080 dot chomp changes the original string. 87 00:04:11.240 --> 00:04:14.360 Ah. Okay, so the bang means watch out, this changes 88 00:04:14.400 --> 00:04:20.079 the original precisely. It's all about clarity and avoiding nasty surprises. 89 00:04:20.439 --> 00:04:23.560 And speaking of clarity, even similar looking operators can behave 90 00:04:23.560 --> 00:04:25.519 differently right like versus. 91 00:04:25.279 --> 00:04:27.759 The word or yeah, that's a subtle but important one. 92 00:04:27.800 --> 00:04:31.000 They both do logical oar but has higher precedence. Higher 93 00:04:31.040 --> 00:04:34.560 precedence meaning it binds more tightly in expressions you almost 94 00:04:34.800 --> 00:04:38.199 always want to use because using or can lead to 95 00:04:38.319 --> 00:04:41.079 unexpected results if you're not careful with parentheses. It's just 96 00:04:41.399 --> 00:04:42.720 clearer and safer. 97 00:04:43.120 --> 00:04:46.439 Got it, use the pipes. Now, the case statement in Ruby, 98 00:04:46.800 --> 00:04:48.399 it's more than just a simple switch, isn't it? 99 00:04:48.439 --> 00:04:51.120 Oh? Absolutely, it's way more powerful. It doesn't use simple 100 00:04:51.240 --> 00:04:55.879 quality checking. It uses this special operator three equal signs. 101 00:04:55.759 --> 00:04:57.160 Triple equals. Okay, what does that do? 102 00:04:57.439 --> 00:05:00.160 Think of it? Less as is exactly equal to? And 103 00:05:00.199 --> 00:05:02.560 more like? Is a kind of or does it match 104 00:05:02.600 --> 00:05:06.040 this pattern? It's called case equality or relationship operator? 105 00:05:06.120 --> 00:05:07.240 So what can you match against? 106 00:05:07.480 --> 00:05:10.040 All sorts of things? You can check if an object 107 00:05:10.079 --> 00:05:12.600 is an instance of a certain class, if a number 108 00:05:12.639 --> 00:05:15.720 falls within a range, if a string matches a rejects. 109 00:05:16.160 --> 00:05:19.759 It makes case statements incredibly versatile for handling different types 110 00:05:19.800 --> 00:05:22.040 of input or situations very elegantly. 111 00:05:22.519 --> 00:05:25.920 That sounds really powerful. Now here's something the book highlights 112 00:05:25.959 --> 00:05:30.360 as one of Ruby's superpowers. Definitions in Ruby are executed. 113 00:05:30.720 --> 00:05:32.160 What exactly does that unlock? 114 00:05:32.399 --> 00:05:36.680 This is? This is fundamental to Ruby's dynamism. It means 115 00:05:36.720 --> 00:05:39.240 that defining a method, or a class or even a 116 00:05:39.240 --> 00:05:42.759 block of code isn't just a static declaration the compiler 117 00:05:42.800 --> 00:05:46.519 handles once it's code that runs at runtime. 118 00:05:46.279 --> 00:05:49.600 Code that runs. So you can define things conditionally exactly. 119 00:05:49.680 --> 00:05:51.879 You could have an if statement and based on some 120 00:05:51.920 --> 00:05:54.560 condition at runtime, you could define method a one way 121 00:05:54.879 --> 00:05:57.399 or define it completely differently. You can literally build or 122 00:05:57.439 --> 00:05:59.759 modify parts of your program while it's running. 123 00:06:00.000 --> 00:06:03.279 Oh, so the program can kind of reshape. 124 00:06:02.839 --> 00:06:06.399 Itself in a way. Yes, it allows for incredible flexibility 125 00:06:06.399 --> 00:06:10.439 and metaprogramming, building domain specific languages. It's a deep topic, 126 00:06:10.480 --> 00:06:13.240 but that dynamic execution of definitions is key. 127 00:06:13.360 --> 00:06:15.800 That sounds like a game changer for certain kinds of problems. 128 00:06:16.079 --> 00:06:19.040 It really can be. And beyond that, Ruby is a 129 00:06:19.040 --> 00:06:23.160 few other maybe smaller but still characteristic quirks, like and 130 00:06:23.279 --> 00:06:25.800 if statements you use elsif not else. 131 00:06:25.600 --> 00:06:28.199 If elsif one word, got it. 132 00:06:28.120 --> 00:06:31.199 And some common words you might think are keywords aren't 133 00:06:31.240 --> 00:06:32.360 strictly reserved. 134 00:06:33.000 --> 00:06:35.319 Loop For example, loop isn't a keywords. 135 00:06:35.439 --> 00:06:38.439 Nope, it's actually a method provided by the kernel module, 136 00:06:38.680 --> 00:06:42.399 which gets mixed into objects, so it's available everywhere. It 137 00:06:42.439 --> 00:06:45.639 speaks to Ruby's flexible grammar. But yeah, it's a method call. 138 00:06:45.639 --> 00:06:48.000 Interesting and variable prefixes. 139 00:06:47.560 --> 00:06:50.720 Right at signals a class variable. Yeah, that belongs to 140 00:06:50.759 --> 00:06:53.240 the class itself, shared by all instances. So if you 141 00:06:53.279 --> 00:06:56.480 had a my dog's class at owner name would be 142 00:06:56.480 --> 00:06:59.040 the same for all dog objects created from that class. 143 00:06:59.079 --> 00:07:01.199 Okay, shared across an instances. Yeah. 144 00:07:01.439 --> 00:07:04.839 And another counterintuitive one can be unless sels the aul's 145 00:07:04.879 --> 00:07:07.639 part runs if the unless condition is actually true, it 146 00:07:07.720 --> 00:07:10.040 reads a bit backwards sometimes, Uh. 147 00:07:09.680 --> 00:07:10.879 Okay, gotta watch out for that. 148 00:07:11.199 --> 00:07:15.240 And simple types things like integers, fixing them traditionally now 149 00:07:15.319 --> 00:07:18.600 just integer true, false, nil. They're passed around as immediate values. 150 00:07:18.639 --> 00:07:22.439 You can't, like modify the number five from inside a method. 151 00:07:22.399 --> 00:07:26.519 Makes sense, And methods implicitly return values always. 152 00:07:26.800 --> 00:07:29.360 A method returns the result of the very last expression 153 00:07:29.360 --> 00:07:31.959 evaluated in its body, so you often don't need to 154 00:07:32.040 --> 00:07:34.680 write return explicitly, which can make code cleaner. 155 00:07:35.040 --> 00:07:39.160 And that if zero dollar equalspily thing you see sometimes. 156 00:07:38.759 --> 00:07:42.160 Ah, yeah, that's a common idiom. Zero dollars is the 157 00:07:42.199 --> 00:07:44.120 name of the script being run and file E is 158 00:07:44.160 --> 00:07:46.360 the name of the current file, So that check is 159 00:07:46.399 --> 00:07:49.319 basically asking am I being run directly as a script, 160 00:07:49.480 --> 00:07:51.560 and if it is, then the code inside that if 161 00:07:51.560 --> 00:07:54.279 block runs. It's often used to put example usage code 162 00:07:54.360 --> 00:07:57.480 or simple tests right inside the library file itself, but 163 00:07:57.560 --> 00:08:00.160 have it only run when you execute that file directly, 164 00:08:00.360 --> 00:08:03.199 not when it's required as a library by another program. 165 00:08:03.319 --> 00:08:05.920 Clever. So lots of these little design choices add up 166 00:08:05.959 --> 00:08:08.480 to make Ruby feel well. 167 00:08:08.319 --> 00:08:12.560 Ruby esque, exactly, flexible, often intuitive, but definitely requires you 168 00:08:12.639 --> 00:08:14.720 to embrace the Ruby way to get the most out 169 00:08:14.720 --> 00:08:14.959 of it. 170 00:08:15.079 --> 00:08:18.759 Okay, we've touched on the philosophy syntax quirks, but Ruby's 171 00:08:18.759 --> 00:08:21.240 elegance really comes into focus when we talk about object 172 00:08:21.319 --> 00:08:24.279 oriented programming, doesn't it. It's not just tacked on. It 173 00:08:24.360 --> 00:08:25.480 seems deeply. 174 00:08:25.319 --> 00:08:29.600 Ingrained, absolutely, and you know, historically OOP had so much 175 00:08:29.680 --> 00:08:32.159 hype around it. There's that great quote from Roger King. 176 00:08:32.399 --> 00:08:34.000 Oh yeah, if you want to sell a cat to 177 00:08:34.039 --> 00:08:36.720 a computer scientist, you have to tell him it's object oriented. 178 00:08:36.759 --> 00:08:37.639 It was the buzzword. 179 00:08:38.000 --> 00:08:42.399 Huh, that's brilliant. But in Ruby it feels less like 180 00:08:42.519 --> 00:08:45.879 hype and more like a genuinely useful tool right, a 181 00:08:45.919 --> 00:08:47.720 meaningful way to think about problems. 182 00:08:47.720 --> 00:08:50.360 As the book says exactly, it's not a magic bullet, 183 00:08:50.360 --> 00:08:54.000 but a powerful approach. And Ruby fully embraces the core 184 00:08:54.159 --> 00:08:59.960 op concepts, objects with encapsulation methods showing polymorphism, classes with 185 00:09:00.039 --> 00:09:02.320 than Herodin's hierarchies. It's all there. 186 00:09:02.519 --> 00:09:05.399 So when you create an object and stantiate it. Ruby 187 00:09:05.399 --> 00:09:07.120 has a constructor concept. 188 00:09:06.840 --> 00:09:10.360 Yes, the initialized method. If you define an initialized method 189 00:09:10.399 --> 00:09:13.080 in your class, it gets called automatically whenever a new 190 00:09:13.120 --> 00:09:15.799 object of that class is created using dot new. 191 00:09:15.840 --> 00:09:19.000 Okay standard constructor. What about destructors cleaning things up? 192 00:09:19.200 --> 00:09:23.440 That's interesting because Ruby has a really effective, well behaved 193 00:09:23.480 --> 00:09:27.480 garbage collection mechanism. It generally does not have any concept 194 00:09:27.480 --> 00:09:31.080 of a destructor. You don't typically need to manually manage 195 00:09:31.159 --> 00:09:35.000 memory deallocation like in some other languages. The garbage collector 196 00:09:35.000 --> 00:09:38.399 handles finding and cleaning up objects that are no longer reachable. 197 00:09:38.600 --> 00:09:42.360 Nice okay. Attributes instance versus class attribute right. 198 00:09:42.399 --> 00:09:46.120 Instance attributes usually written with a single at age, belong 199 00:09:46.240 --> 00:09:49.440 to a specific object instance. Each dog object would have 200 00:09:49.480 --> 00:09:50.200 its own at. 201 00:09:50.080 --> 00:09:52.120 Age unique to each object. Yes. 202 00:09:52.399 --> 00:09:56.919 Class attributes written at owner name belong to the class itself. 203 00:09:56.919 --> 00:09:59.759 They're shared across all instances of that class. So all 204 00:09:59.840 --> 00:10:02.000 my dog's objects would share the same at. 205 00:10:01.960 --> 00:10:04.279 Owner name shared value is that common. 206 00:10:04.360 --> 00:10:07.519 It exists, But you have to be careful at variables 207 00:10:07.519 --> 00:10:10.240 because they're also inherited by subclasses in ways that can 208 00:10:10.279 --> 00:10:14.279 sometimes be surprising. Often, a better alternative for storing data 209 00:10:14.320 --> 00:10:16.840 related only to the class itself and not shared with 210 00:10:16.879 --> 00:10:19.720 instances or subclasses in the same way is to use 211 00:10:19.759 --> 00:10:22.240 an instance variable inside a class method. 212 00:10:22.559 --> 00:10:26.279 An instance variable inside a class method yeah, okay, a 213 00:10:26.320 --> 00:10:27.000 bit more nuanced. 214 00:10:27.120 --> 00:10:29.919 Yeah, it's called a class instance variable. It avoids some 215 00:10:29.960 --> 00:10:32.519 of the pitfalls at variable. 216 00:10:32.200 --> 00:10:36.600 Good distinction, and methods instance versus class pretty straightforward. 217 00:10:36.759 --> 00:10:39.960 Instance methods operate on the data of a specific object 218 00:10:40.200 --> 00:10:44.080 at age, et cetera. Class methods often define like def 219 00:10:44.159 --> 00:10:47.639 self dot sum method performed tasks related to the class 220 00:10:47.639 --> 00:10:50.960 as a whole, maybe like creating instances with specific properties 221 00:10:51.039 --> 00:10:54.279 or managing class level state. They achieve class wide effects, 222 00:10:54.399 --> 00:10:55.200 and Ruby. 223 00:10:54.919 --> 00:10:57.480 Has those handy shortcuts for getters and setters. 224 00:10:57.559 --> 00:11:00.120 Oh yeah, at reader at writer and a traccessor there 225 00:11:00.200 --> 00:11:03.840 super common at reader dot name automatically creates a method 226 00:11:03.879 --> 00:11:07.159 name to read the at name instance variable at writer 227 00:11:07.320 --> 00:11:09.559 creates name to write it, and at t accessor does both. 228 00:11:09.639 --> 00:11:11.600 Gives a lot of boilerplate code totally. 229 00:11:11.279 --> 00:11:14.559 And inside an instance method, the keyword self always refers 230 00:11:14.559 --> 00:11:17.120 to the object the method was called on the receiver wellout. 231 00:11:17.120 --> 00:11:19.759 Controlling access public private. 232 00:11:19.480 --> 00:11:23.879 Ruby uses public, private, and protected keywords to control method visibility. 233 00:11:24.519 --> 00:11:28.200 By default, methods are public. Private methods can only be 234 00:11:28.240 --> 00:11:32.840 called implicitly without an explicit receiver like self from within 235 00:11:32.960 --> 00:11:37.080 the defining class. Protected is similar to private, but allows 236 00:11:37.120 --> 00:11:40.879 calls from other instances of the same class or subclasses. 237 00:11:40.360 --> 00:11:42.159 And the instance variables themselves. 238 00:11:42.240 --> 00:11:46.000 The at ones critically instance variables at my var are 239 00:11:46.080 --> 00:11:48.600 always private. You can only access them from outside the 240 00:11:48.639 --> 00:11:52.840 object if the class explicitly provides accessor methods like those 241 00:11:52.879 --> 00:11:53.600 generated by a. 242 00:11:53.519 --> 00:11:55.600 Treater always private and class methods. 243 00:11:55.679 --> 00:11:58.320 You can control their visibility too, using private class method 244 00:11:58.360 --> 00:12:00.399 dot my class method right now. 245 00:12:00.480 --> 00:12:04.519 Inheritance the book calls code reuse the holy grail of 246 00:12:04.519 --> 00:12:08.279 computer science. How does inheritance fit into Ruby's OOP. 247 00:12:08.399 --> 00:12:11.159 It's a core strength. Inheritance lets you create a new 248 00:12:11.200 --> 00:12:14.879 class a subclass that inherits properties and methods from an 249 00:12:14.919 --> 00:12:18.080 existing class. A superclass. You can then add new features 250 00:12:18.159 --> 00:12:21.320 or override existing ones in the subclass. It's a fundamental 251 00:12:21.320 --> 00:12:23.240 way to reuse code and model is. 252 00:12:23.279 --> 00:12:25.480 Relationships build on what's already there. 253 00:12:25.600 --> 00:12:31.600 Exactly, and that leads directly to polymorphism, which means literally 254 00:12:31.720 --> 00:12:35.720 many forms. It's the idea that different objects can respond 255 00:12:35.759 --> 00:12:38.840 to the same message, the same method call in different ways. 256 00:12:39.480 --> 00:12:44.240 Often people mean inheritance polymorphism, where a subclass can redefine 257 00:12:44.240 --> 00:12:47.799 a method inherited from its superclass, providing a specialized version 258 00:12:47.840 --> 00:12:50.360 of that behavior. So you can treat objects of different 259 00:12:50.480 --> 00:12:54.960 subclasses similarly, but they'll act appropriately based on their specific type. 260 00:12:55.159 --> 00:12:57.519 Okay, so you can call dot speak on different animal 261 00:12:57.559 --> 00:13:00.559 objects and they each make their own sound perfect. Example. 262 00:13:00.759 --> 00:13:03.440 Now where Ruby gets really cool for understanding your code 263 00:13:03.519 --> 00:13:04.360 is its reflection. 264 00:13:04.519 --> 00:13:07.279 API reflection like looking in a mirror. 265 00:13:07.039 --> 00:13:09.720 Kind of it lets your program examine itself at runtime. 266 00:13:09.799 --> 00:13:13.360 You can ask objects about their type, their capabilities, their ancestry. 267 00:13:12.960 --> 00:13:13.960 What methods do you use. 268 00:13:14.080 --> 00:13:16.360 You can use dot class to get the exact class 269 00:13:16.360 --> 00:13:19.679 of an object. Then there's ISA or it's alias kind 270 00:13:19.759 --> 00:13:22.440 of these check if an object is an instance of 271 00:13:22.480 --> 00:13:24.919 a specific class or any of its superclasses. 272 00:13:25.000 --> 00:13:26.639 Ah, the dog is a mammal thing. 273 00:13:26.720 --> 00:13:30.440 Exactly mydog dot ISA mammal would be true, but instance 274 00:13:30.480 --> 00:13:34.279 of stricter mydog dot instance mammal would be false because 275 00:13:34.279 --> 00:13:37.519 its direct class is dog dot. ISA also works with 276 00:13:37.600 --> 00:13:39.840 modules that have been mixed in, which is super useful. 277 00:13:40.159 --> 00:13:43.559 An array ISA innumerable for instance. 278 00:13:43.240 --> 00:13:47.200 So ISA checks the whole inheritance chain and mix its right. 279 00:13:47.440 --> 00:13:50.440 And sometimes maybe the most important check is respond to 280 00:13:50.440 --> 00:13:53.399 respond to yeah, it just asks, hey, object, can you 281 00:13:53.440 --> 00:13:55.879 do this thing? It checks if the object has a 282 00:13:55.879 --> 00:13:58.919 method with a given name, regardless of its class or inheritance. 283 00:13:59.360 --> 00:14:02.080 This is key to Ruby's duck typing. If it walks 284 00:14:02.120 --> 00:14:03.879 like a duck and quacks like a duck, just treat 285 00:14:03.879 --> 00:14:06.120 it like a duck. If it responds to it dot quack, 286 00:14:06.200 --> 00:14:07.600 you can call dot quack on it. 287 00:14:07.679 --> 00:14:10.320 Focus on capabilities, not just lineage precisely. 288 00:14:10.519 --> 00:14:13.480 You can also use methods like constants to see defined constants, 289 00:14:13.600 --> 00:14:16.840 nesting to see the current module class nesting, and ancestors 290 00:14:16.879 --> 00:14:20.200 to get the full inheritance chain, including mixin's for a class. 291 00:14:20.559 --> 00:14:25.279 It's incredibly powerful for understanding and even manipulating your program dynamically. 292 00:14:25.519 --> 00:14:29.399 Okay, that dynamic introspection sounds really powerful. Let's shift gears 293 00:14:29.399 --> 00:14:33.159 slightly and dive into practical mastery, starting with strings. The 294 00:14:33.159 --> 00:14:35.799 book poses that question from a computer science professor. 295 00:14:35.919 --> 00:14:38.879 Ah, yes, what is the most important data type? 296 00:14:39.360 --> 00:14:41.960 And the answer was this string. 297 00:14:42.120 --> 00:14:45.399 Which when you think about it, web pages, source code, 298 00:14:45.639 --> 00:14:49.799 user input documents, configuration files, so much of what computers 299 00:14:49.799 --> 00:14:50.799 handle is text. 300 00:14:51.200 --> 00:14:54.000 It makes sense and Ruby's strings are pretty flexible, right. 301 00:14:53.919 --> 00:14:57.759 Very flexible. You have your standard single and double quoted strings. 302 00:14:58.159 --> 00:15:03.440 Double quoted strings allow interpal and escape sequences like n interpolation. Yeah, 303 00:15:03.519 --> 00:15:06.759 Embedding Ruby code inside a string using hashtag pv e 304 00:15:07.039 --> 00:15:10.639 us so hello hashtag your name would put the value 305 00:15:10.639 --> 00:15:13.840 of the name variable right into the string. It implicitly 306 00:15:13.879 --> 00:15:16.120 calls narrows on whatever's inside the braces. 307 00:15:16.200 --> 00:15:18.279 Andy, what about other ways to make strings? 308 00:15:18.399 --> 00:15:21.440 There are alternate quoting mechanisms like per set tea for 309 00:15:21.480 --> 00:15:23.840 single quoted behavior and percent highs two two one r 310 00:15:23.919 --> 00:15:27.039 tq for double quoted behavior. Useful if your string contains 311 00:15:27.080 --> 00:15:30.080 lots of quotes itself. And then there are here documents 312 00:15:30.159 --> 00:15:33.840 using identifier identifier which are great for embedding large multi 313 00:15:33.879 --> 00:15:34.840 line blocks of text. 314 00:15:35.120 --> 00:15:38.039 Okay, lots of ways to represent them YEA, manipulating them. 315 00:15:37.960 --> 00:15:41.240 Tons of power. There you can get the length, process 316 00:15:41.279 --> 00:15:43.639 them line by line using each line, or character by 317 00:15:43.679 --> 00:15:47.320 character with each char. You can extract substrings using ranges 318 00:15:47.360 --> 00:15:50.320 like mystering eight point one three, or even using regular 319 00:15:50.360 --> 00:15:52.279 expressions like mistring pattern. 320 00:15:52.080 --> 00:15:55.120 Using rejects for extraction. Nice white space. 321 00:15:54.879 --> 00:15:57.919 Easy strip removes leading and trailing white space, L strip 322 00:15:58.080 --> 00:16:01.559 just leading, l strip just trailing. Very common operations, and 323 00:16:01.639 --> 00:16:04.879 you can repeat strings with the multiplication operator not ten 324 00:16:04.960 --> 00:16:05.759 plus batman. 325 00:16:06.120 --> 00:16:11.279 Huh. Okay, now that interpolation with hashtagzines common. Are there pitfalls? 326 00:16:11.480 --> 00:16:14.399 The main pitfall mentioned, and it's a big one, is 327 00:16:14.559 --> 00:16:17.919 using Evil for anything involving external input. Evil takes a 328 00:16:17.960 --> 00:16:20.000 string and executes it as ruby code. 329 00:16:20.120 --> 00:16:22.600 Sounds powerful and dangerous. 330 00:16:22.200 --> 00:16:25.320 Extremely dangerous if the string comes from an untrusted source 331 00:16:25.440 --> 00:16:28.159 like user input. The book flat out calls it almost 332 00:16:28.200 --> 00:16:31.039 always the worst option. It's slow and opens up massive 333 00:16:31.080 --> 00:16:34.639 security holes. You should basically never use Evil on external data. 334 00:16:34.720 --> 00:16:37.919 It's really only for very specific metaprogramming task where you 335 00:16:37.960 --> 00:16:40.120 fully control the code being evaluated. 336 00:16:40.360 --> 00:16:43.960 Okay, big red flag on Evil. Good to know any 337 00:16:44.000 --> 00:16:45.480 other cool string utilities. 338 00:16:45.759 --> 00:16:49.320 The book mentions things like calculating Levenstein distance the edit 339 00:16:49.360 --> 00:16:53.480 distance between two strings, useful for spell checkers or finding similarities. 340 00:16:53.840 --> 00:16:57.240 And it points to libraries like active support from rails 341 00:16:57.480 --> 00:16:59.840 which add helpful methods like word wrap. 342 00:17:00.080 --> 00:17:03.399 Right, let's move from text to numbers. The computer's native tongue. 343 00:17:03.399 --> 00:17:06.920 As you said, Ruby handles the basics integers floats. But 344 00:17:07.039 --> 00:17:08.720 what are the pleasant surprises. 345 00:17:09.160 --> 00:17:13.279 Oh, Ruby's numerical tower is quite sophisticated beyond standard integers. 346 00:17:13.319 --> 00:17:16.039 If a number gets too big, it automatically transitions into 347 00:17:16.079 --> 00:17:20.640 a big num, allowing for arbitrarily large integer calculations without overflow. 348 00:17:20.720 --> 00:17:22.759 Automatic handling of huge numbers. Nice. 349 00:17:22.839 --> 00:17:26.279 Then there's Big Decimal standard Floating point numbers float can 350 00:17:26.319 --> 00:17:29.480 have tiny precision errors because of how they're represented in binary. 351 00:17:29.759 --> 00:17:31.680 You know, zero point one plus point two not being 352 00:17:31.720 --> 00:17:35.480 exactly point three. Big decimal solves this by providing precise 353 00:17:35.640 --> 00:17:38.279 decimal arithmetic, crucial for financial. 354 00:17:37.759 --> 00:17:40.839 Calculations, so for money, use Big decimal definitely. 355 00:17:40.960 --> 00:17:44.400 And there's also rational for representing exact fractions like rational 356 00:17:44.440 --> 00:17:49.119 one three. This avoids floating point inaccuracies entirely for division 357 00:17:49.119 --> 00:17:55.720 that results in repeating decimals, for instance, rational one hundred zero, zero, one, one, rational, three, 358 00:17:55.759 --> 00:17:57.559 one thousand keeps perfect precision. 359 00:17:57.759 --> 00:18:02.160 Wow. Okay, so bigm big decimal, rational, pretty comprehensive. What 360 00:18:02.240 --> 00:18:03.359 about complex numbers? 361 00:18:03.640 --> 00:18:06.480 Yep, built right in you can create complex numbers easily. 362 00:18:06.799 --> 00:18:09.519 Three dot im gives you the imaginary number three I, 363 00:18:09.720 --> 00:18:13.720 and you can perform standard complex arithmetic. There's also complex 364 00:18:13.759 --> 00:18:17.200 dot polar for polar coordinates. It shows Ruby's strength beyond 365 00:18:17.319 --> 00:18:19.799 just web deev. It's capable in scientific context too. 366 00:18:19.880 --> 00:18:22.119 Cool. Any advanced math stuff, Yeah. 367 00:18:22.119 --> 00:18:24.920 Ruby has built in support for prime number operations. Through 368 00:18:24.960 --> 00:18:27.960 the prime library. You can test for primality, generate primes, 369 00:18:27.960 --> 00:18:30.920 and even get the prime factorization of a number using prime. 370 00:18:30.759 --> 00:18:33.160 Division prime division. Okay, statistics yep. 371 00:18:33.200 --> 00:18:36.240 There are common statistical functions available, often through gems or 372 00:18:36.279 --> 00:18:39.680 standard library editions, for calculating things like mean, median mode, 373 00:18:39.759 --> 00:18:44.119 standard deviation, variance, correlation coefficients, the usual suspects for basic 374 00:18:44.160 --> 00:18:45.079 data analysis. 375 00:18:45.319 --> 00:18:48.119 One last thing on numbers. That quote about random numbers, ah, 376 00:18:48.240 --> 00:18:49.039 John von Neuman. 377 00:18:49.200 --> 00:18:54.000 Yes, Ruby's rand function, like in most languages, generate pseudorandom numbers. 378 00:18:54.240 --> 00:18:58.039 They look random, but they're produced by a deterministic algorithm. 379 00:18:58.039 --> 00:18:59.519 So not truly random. 380 00:18:59.799 --> 00:19:04.079 Now truly unpredictable in a physical sense. Von Neumann's quote 381 00:19:04.279 --> 00:19:08.440 anyone who attempts to generate random numbers by deterministic means is, 382 00:19:08.799 --> 00:19:11.160 of course living in a state of sin is just 383 00:19:11.200 --> 00:19:15.000 a witty reminder of that limitation. It's important to understand 384 00:19:15.039 --> 00:19:17.519 what computer randomness actually is. 385 00:19:17.759 --> 00:19:20.519 A great point. Okay, let's shift to organizing data and 386 00:19:20.640 --> 00:19:25.079 time collections like arrays and hashes and how Ruby handles time. 387 00:19:25.400 --> 00:19:28.559 These seem like areas where Ruby really offers elegant solutions. 388 00:19:28.640 --> 00:19:31.640 Definitely. Arrays and hashes are workhourses in Ruby, and they're 389 00:19:31.720 --> 00:19:32.960 very flexible. 390 00:19:32.599 --> 00:19:35.480 So a rays more than just lists much more. 391 00:19:35.519 --> 00:19:38.640 You've got basic access with indexes first, last getting the 392 00:19:38.720 --> 00:19:41.599 length or size. But sorting is where things get interesting, 393 00:19:41.839 --> 00:19:43.480 especially sortby Sortpye. 394 00:19:43.680 --> 00:19:45.160 You mentioned the short seat transform. 395 00:19:45.440 --> 00:19:49.440 Yeah, it's a pattern sort be often implements. Imagine sorting 396 00:19:49.440 --> 00:19:52.839 files by size, calling filed out size for every comparison 397 00:19:52.920 --> 00:19:55.839 during the sort can be slow if you have many. 398 00:19:55.640 --> 00:19:57.799 Files right, lots of disc access. 399 00:19:57.480 --> 00:20:01.960 Maybe exactly Sort b file file file calculates the size 400 00:20:02.000 --> 00:20:04.599 once for each file, creating a temporary list of sizes. 401 00:20:05.119 --> 00:20:07.480