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| === ChanServ changed the topic of #ubuntu-classroom to: Welcome to the Ubuntu Classroom - http://wiki.ubuntu.com/Classroom || Support in #ubuntu || Upcoming Schedule: http://is.gd/8rtIi || Current Session: Introduction to C#: Session 4 - Instructor: juju2143 || Questions in #ubuntu-classroom-chat | ||
| pleia2 | juju2143: you about? | 21:02 |
|---|---|---|
| pleia2 | hopefully he just got tied up elsewhere and will arrive soon :) | 21:05 |
| juju2143 | ohhhh right | 21:12 |
| juju2143 | the course. | 21:12 |
| juju2143 | everyone's there? | 21:12 |
| sirmacik | yep | 21:13 |
| sirmacik | I'm ready (; | 21:13 |
| sirmacik | hello juju2143 and pleia2 | 21:14 |
| sirmacik | \o | 21:14 |
| juju2143 | hello. | 21:14 |
| juju2143 | so last Friday, we did classes | 21:15 |
| === yofel_ is now known as yofel | ||
| juju2143 | now we'll do inheritance. | 21:16 |
| juju2143 | It's one of the advanced features of OOP | 21:16 |
| juju2143 | So, like our last example, we created a Person class | 21:19 |
| sirmacik | hmm.. I think I've lost it... could You paste it to some nopaste? | 21:20 |
| juju2143 | say you are programming some RPG game, you would like a Warrior or a magician | 21:20 |
| juju2143 | So you could create a warrior class and a Magician class | 21:20 |
| juju2143 | These classes would be exactly the same, with the exceptions of some methods such as doMagic(), or mana level | 21:22 |
| juju2143 | So why not put these methods and attributes in common in the same class? | 21:24 |
| juju2143 | I would compare it to the apt-get system of Ubuntu | 21:24 |
| juju2143 | like, Warrior and Magician both depends on libperson | 21:24 |
| === Pendulum_ is now known as Pendulum | ||
| juju2143 | same thing in C# and in every OOP language that supports inheritance | 21:25 |
| juju2143 | the warrior class would include the Person class and take its attributes, etc. | 21:26 |
| juju2143 | so open your console application. | 21:27 |
| juju2143 | in Main.cs you would have something like this: | 21:28 |
| juju2143 | Class Person | 21:28 |
| juju2143 | { | 21:28 |
| juju2143 | ... | 21:28 |
| juju2143 | } | 21:28 |
| juju2143 | Class Warrior : Person | 21:29 |
| juju2143 | { | 21:29 |
| juju2143 | ... | 21:29 |
| juju2143 | } | 21:29 |
| juju2143 | class Magician : Person | 21:29 |
| juju2143 | { | 21:29 |
| juju2143 | ... | 21:29 |
| juju2143 | } | 21:29 |
| juju2143 | (right, the C in class should be lowercased) | 21:29 |
| juju2143 | So it's really simple. | 21:30 |
| juju2143 | You add this : Person thing | 21:30 |
| juju2143 | and you can add methods in Warrior like if you were in Person | 21:31 |
| juju2143 | same thing in Magician, but without the methods in Warrior. | 21:31 |
| juju2143 | sirmacik, they are not needed, just have a console application handy. And paste the classes in there. | 21:32 |
| juju2143 | so if you have this: | 21:33 |
| juju2143 | class Person | 21:33 |
| juju2143 | { | 21:33 |
| juju2143 | public Person(string Sex) | 21:34 |
| juju2143 | { | 21:34 |
| juju2143 | m_sex = sex; | 21:34 |
| juju2143 | } | 21:34 |
| juju2143 | public string m_sex = "Male"; | 21:34 |
| juju2143 | } | 21:34 |
| juju2143 | so in your Main() you can instanciate Person like this: | 21:35 |
| juju2143 | Person a = new Person("Male"); | 21:35 |
| juju2143 | you should, even there is nothing in Warrior, instanciate it like Person, just replace Person with Warrior | 21:36 |
| juju2143 | So, that's it for inheritance. | 21:38 |
| sirmacik | :o | 21:38 |
| sirmacik | nice (; | 21:38 |
| juju2143 | Now there something else worth mentioning today. | 21:39 |
| juju2143 | (damn I forgot what it's called) | 21:39 |
| juju2143 | So you can have methods of the same name in same class | 21:39 |
| juju2143 | Only difference is the type of return and/or number of arguments. | 21:40 |
| juju2143 | (hm, finally, disregard the type of return, the compiler have no way to know which type to return) | 21:42 |
| juju2143 | So, say you have a method called doSomething. | 21:43 |
| juju2143 | You can have a dosomething that takes no arguments, one that takes a string, one that takes an int, one that takes one string and one int, etc. | 21:44 |
| juju2143 | So you could have endless methods with the same name. | 21:45 |
| juju2143 | Also, something interesting with inheritenceyou can do is polymorphism. | 21:47 |
| juju2143 | Now you are wondering what's this big word. | 21:48 |
| juju2143 | Something you should know is that all classes inherits from System.Object | 21:48 |
| juju2143 | something you can do is simply put your Person class in an object | 21:50 |
| pedro3005 | juju2143, sorry | 21:50 |
| juju2143 | like this: object o = a | 21:51 |
| juju2143 | pedro3005, oh no problem | 21:51 |
| juju2143 | so it's kinda useful if you have a method, say doSomething, who takes an argument you don't know what ii is | 21:52 |
| juju2143 | it* | 21:52 |
| juju2143 | public void doSomething(object o) | 21:53 |
| juju2143 | { | 21:53 |
| juju2143 | // do something with o, who would be anything | 21:54 |
| juju2143 | } | 21:54 |
| pedro3005 | and then could you test upon the type? like if (isint) or something? | 21:54 |
| juju2143 | yeah, something like that | 21:54 |
| juju2143 | then you can give doSomething a Person or a string | 21:55 |
| juju2143 | same thing if you replace object by Person in the above example | 21:56 |
| juju2143 | you could give a Warrior or a Magician to your method | 21:56 |
| juju2143 | So you transformed your Person into an object | 21:58 |
| juju2143 | now to do the inverse you could write this: | 21:58 |
| juju2143 | Person p = (Person)o | 21:58 |
| juju2143 | (you need to cast it) | 21:58 |
| pedro3005 | so you'd be transforming o into a person object? | 21:59 |
| juju2143 | yep | 21:59 |
| pedro3005 | but that's weird | 21:59 |
| juju2143 | this is encapsulation. | 21:59 |
| pedro3005 | what is o? | 21:59 |
| pedro3005 | can you transform anything into a person object? | 22:00 |
| juju2143 | o is an object containing a Person | 22:00 |
| juju2143 | so: | 22:00 |
| juju2143 | Person a = new Person("Male"); | 22:00 |
| juju2143 | object o = a; | 22:00 |
| juju2143 | Person p = (Person)o | 22:01 |
| juju2143 | ; | 22:01 |
| juju2143 | like you could do this: | 22:01 |
| juju2143 | double a_double = (double)an_integer; | 22:02 |
| juju2143 | where an_integer is an int variable | 22:02 |
| juju2143 | this is casting (and not castration) | 22:04 |
| juju2143 | oh yeah, for the thing with methods of the same name | 22:06 |
| juju2143 | it doesn't work well with constructors | 22:06 |
| juju2143 | so you have to do this: | 22:07 |
| juju2143 | public Person(string arg) : this() | 22:07 |
| juju2143 | { | 22:07 |
| juju2143 | } | 22:07 |
| juju2143 | in fact it works without this() (i think) | 22:08 |
| juju2143 | but there you can reuse the constructor without arguments in the constructor with arguments | 22:08 |
| juju2143 | so this won't work: | 22:09 |
| juju2143 | public Person(string args) | 22:09 |
| juju2143 | { | 22:09 |
| juju2143 | Person(); // or this(); | 22:09 |
| juju2143 | } | 22:09 |
| juju2143 | it would give an error. | 22:09 |
| juju2143 | So I think that's it for today for inheritence and that thing I forgot the name | 22:11 |
| juju2143 | for today | 22:11 |
| juju2143 | homework: mess with these things | 22:11 |
| sirmacik | are there going to be next lessons? | 22:11 |
| juju2143 | i don't know, I think so | 22:12 |
| juju2143 | come back tomorrow, we'll see. Maybe we'll do graphics. | 22:12 |
| sirmacik | oh, that'd be great (; | 22:13 |
| juju2143 | yep :P | 22:13 |
| sirmacik | see You then, good night | 22:14 |
| sirmacik | (it's 23:14 here) | 22:14 |
| juju2143 | good night. | 22:16 |
| juju2143 | :P | 22:16 |
| pedro3005 | alright juju2143, thanks for the lesson | 22:18 |
| juju2143 | your welcome. | 22:20 |
| ClassBot | There are are 10 minutes remaining in the current session. | 22:22 |
| pleia2 | adding next one to the calendar | 22:22 |
| ClassBot | There are are 5 minutes remaining in the current session. | 22:25 |
| === ChanServ changed the topic of #ubuntu-classroom to: Welcome to the Ubuntu Classroom - http://wiki.ubuntu.com/Classroom || Support in #ubuntu || Upcoming Schedule: http://is.gd/8rtIi | ||
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