learning to walk in shoesblog.napcs.com/wp-content/uploads/2009/05/tccc_vi_shoes.pdf · you often...
TRANSCRIPT
brian who?
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So, who is this guy?Visit http://www.napcs.com/http://www.snippetstash.com/http://www.feelmyskills.com/http://www.webdesignfordevelopers.com
Shoes?
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A talk about shoes would be completely inappropriate at a code camp. So we’re not talking about these kinds of shoes. Although, a search for shoes on Google will turn up lots of stuff like this.
OMG! SHOES!
x-platform GUI in Ruby!4
We’re talking about Shoes, a cross-platform framework for making GUI apps, using the Ruby language.
_why_ ruby?
• Highly dynamic
• Very high level
• 100% object oriented
• 100% open-source
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It’s also incredibly easy to learn.
data types in ruby
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One of the nice things about Ruby is that it strives to be easy to read. Here, we’re declaring some variables and setting values.
variablesConstants
Local variable
Instance variable
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Like most languages, you’ve got constants, local variables, and instance variables. The convention in Ruby is to use all capital letters for constants, but anything that starts with a capital letter is considered constant.
You can actually change values of constants at runtime, but you will get a warning about that.
Instance variables get the @ sign.
Ruby is dynamically typed
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Anyone know what dynamically typed is?
What’s the opposite of dynamically typed?
don’t confuse that with weak typed!
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a type can be defined explicitly
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or implicitly
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...but a string and a number can’t just be
mashed together without help.
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bad
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You’ll get a runtime error because you can’t add a string to a number
better
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The to_s method converts many types of objects to strings.
awesome.
#{} embeds an expression in a string,
converting the result to a string!
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You can embed any expression this way and it will automatically cast the value to a string, even if it’s a null value.
you’re going to see#{}
a lot.
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ruby has simple logic
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defining methods
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def is so much nicer than function.
ruby has some simple rules
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everything isan object
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There’s no such thing as a primitive in Ruby. Even a string or an integer is an object.
every statement returns a value.
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With methods, if it’s not explicit with a return, then the return value is the value of the last statement.
everything evaluatesto TRUE exceptnil and FALSE.
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1 is true. 0 is not false.
everything is an object.everything is a class.
classes can be boring or awesome.
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booooooring
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The “java” way. This is on the way out because it’s stupid. Here we’re declaring instance variables, getters, and setters. Essentially creating properties.
awesome.
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attr_accessor creates variables, getters, and setters.
as you write rubyyou often see codethat writes code.
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Metaprogramming!
arrays and hashes are important. Pay attention.
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They’re everywhere.
arrays
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Square brackets denote hashes.
hash
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Curly braces and => are for hashes.
whenever you see
=>
you’re dealing with a hash.
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Hashrocket.
methods that take hashes as parameters
are very, very common.
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this method takes one parameter.
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Only one parameter which is a hash. Hashes are amazing because you can actually send the parameters into a method in any order, and it’s nicely self-documenting. No referencing the api to figure out which parameter is the width.
now let’stake a walk
around the Block
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Blocks are like closures or anonymous fuctions
blocks let us loop
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We can use them for looping instead of having to track an array or hash position.
so, a regular class...
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...can be improved with blocks
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This is a standard pattern in Ruby classes.
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Obligatory LOLCAT is obligatory!
make constructors accept hashes...
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...and use a block toiterate over keys and
values to assign instance variables.
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this technique makes writing DSLs
easy.
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no. wrong.
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DomainSpecific
Language
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ruby has “sugar” tomake it easy to read.
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Parenthesis are optional in many cases, especially when it’s obvious.
oh yeah...
= is assignment.
== is equality.
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ok now you’re warmed up.
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but you have to Tie your Shoes
before you can run!
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you’re supposed to BOO!
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and no, this doesn’t excuse the bad joke.
Shoes is a DSL.
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a Shoes app is a ruby object.
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your code lives inside of this object using blocks.
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it’s super easy.
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REALLY super easy.
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so, basic stuff.
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Shoes.app
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background
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background
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backgrounds can usehex codes too.
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layout works likeyou wish HTML and CSS works
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stacks
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all sub elements stack.
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flows
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all sub elements flow
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combine stacksand flows
to make complexlayouts
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two column with header
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the Shoes window is also
a flow.
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simple text
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edit_line
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edit_line
great for passwordz
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edit_box
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list_box
arrays and hashes are everywhere.
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radio
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check
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use instance variablesto reference controls.
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grabbing and showing input
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Use the .text method to grab the text from the textbox.
any object is fair game.even stacks and floats
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append to a stack
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The @names section contains the names we add, and names get added when we click the button.
Clearing a stack
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Stacks and flows can be cleared as well. Clear can take a block which you can use to place new content in the stack or flow.
Windows
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windows arelike new apps.
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So instance variables are isolated.
each screenis a url.
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urls and methods
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We can use a nice MVC-style structure here. Notice that we can wrap blocks in methods so we can easily call them.
shoes canplay music
and movies...
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The video player plays mp3s, oggs, avis, movs, flvs and more.
load images...
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...and open URLs in browsers.
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you can use any gemwith Shoes.
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There are hundreds of libraries out there for doing pretty much anything. Twitter, Youtube, Flickr, Last.fm, and anything in between.
shoes can installlibraries for you.
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When the app starts, these libraries get installed to the user’s home directory.
you can alsoaccess OS stuff.
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Accessing standard dialogs and the clipboard is pretty simple.
demos
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http://github.com/napcs/shoes_demo_apps/
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Either check it out with git or click the download link and unzip the package.
twitter: bphogan
http://www.napcs.com/
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