Nathaniel Talbott: Why Camping Matters
“I don’t know about you, but I am totally psyched about this conference!” Nathaniel has spoken at every RubyConf.
Every talk needs a metaphor, and this talk’s will be the bacon, egg, and cheese biscuit.
Bacon
The bacon is the connection to the creator, and to chunky bacon. It’s a 4k micro framework created by _why.
A whole Camping app goes in a single file and is a typical MVC.
Camping.goes :Blog
module Blog::Controllers
class Index < R '/' # route to /
def get
"Hello Rubyconf!"
end
end
end
...
$ camping blog.rb
# blah blah, up on localhost:3301
Hooray, Hello World!. Let’s start doing more MVC:
Camping.goes :Blog
module Blog::Controllers
class Index < R '/' # route to /
def get
render :index
end
end
class Add < R '/add'
render :add
end
end
module Blog::Views
def index
# this is markaby
a "add post", :href => R(Add)
end
def add
form :method => :post do
fieldset do
label "Title: "
input :name => :title; br
label "Body"
textarea :name => :body; br
end
end
end
end
Camping is nice when making a sketch of the app, and eliminates all the unnecessary crap. To that extent, it’s wonderful for rapid prototyping. We’ve already got most of a Blog skeleton. Now, time for M of MVC.
Camping.goes :Blog
module Blog::Controllers
class Index < R '/' # route to /
def get
render :index
end
end
class Add < R '/add'
def get
render :add
end
def post
Post.create!(@input)
redirect Index
end
end
end
module Blog::Views
def index
# this is markaby
a "add post", :href => R(Add)
end
def add
form :method => :post do
fieldset do
label "Title: "
input :name => :title; br
label "Body"
textarea :name => :body; br
end
end
end
end
# This is ActiveRecord under the covers, that's _not_ part of the 4k
module Blog::Models
class Post < Base; end
# Migrations go inline
class CreatePost < V 1
def self.up
create_table :blog_posts do |t|
t.column :title, :string
t.column :body, :text
end
end
end
end
def Blog.create;
Cool, we’ve got something working. It’d be nice if we knew what was there…
module Blog::Views
def index
@posts.each do |e|
h2{e.title}
p e.body
hr
end
# this is markaby
a "add post", :href => R(Add)
end
end
Permalinks:
class View < R '/view/(\d+)'
def get(id)
@post = Post.find(id)
render :view
end
end
[As you can see, this all happened very fast, as we're only 17 minutes in so far.] Nathaniel adds comments in the next 4 minutes.
Egg
So, that’s really most of Camping. To keep the metaphor going, we need to break some eggs (over Rails). Some differences between Rails & Camping:
- Convention over configuration vs. minimalizism (nothing to configure)
- Opinionated vs. wackyness (“Camping isn’t so much opinionated as it is… strange.”)
- Boring vs. different
- Just like always, but better vs. “More flexible than a wet noodle”
- Lots and lots of helpers vs. diy
- Rails vs. Ruby
- Daunting to hack on vs. hackable (if odd)
- Encourages conformance vs. encourages experimentation
Cheese
Actually hacking on stuff is fun. That’s why Camping & any other cool, out-there framework or language is there: “we need to feed our inner hacker!” Keys to feeding your inner hacker:
- Needs to be regular (daily would really be great)
- Eat a variety of foods (different is good: Rails Monday, Camping Tuesday)
- You have to feed on things that you’re passionate about
Biscuit
The biscuit is the Community. Why do people who have been to both RailsConf and RubyConf prefer RubyConf? [A show of hands confirmed this.] RubyConf is still small, and it’s the hobbyist conference. Both of those are not true of RailsConf. We, the Ruby community, need both conferences, with RailsConf bringing the momentum and RubyConf bringing the vitality.
Questions
Testing: There’s a testing framework for Camping called Mosquito.
Production: Nathaniel does use it in production, but not for clients.
Intranet apps would be great.
Nathan Sobo: Treetop: Bringing the Elegance of Ruby to Syntactic
Analysis
Earlier in the day, a significant but small number of folks raised their hands when asked if they had ever written a parser. However, many of us have written ad-hoc parsers on other stuff (in regexes, usually). Why don’t regular programmers use the same tools as language designers for creating parsers? Because the tools for making parsers have a really high barrier to entry, even though regexes and loops make for brittle software. Hopefully, some new tools will lower this barrier to entry. Treetop is an attempt at this.
What is a Context Free (Generative) Grammar? A grammar is a program, a program that generates every possible string in a language. However, there’s a problem with this model of grammars, as sometimes there’s ambiguity (think of if/else with ambigous nesting). Instead, do Parsing Expression Grammars [PEG], which Treetop uses, and work on recognizing language rather than generating it.
PEGs are just a generalization of ur-regexes, but are more powerful because they can do recursion. Here’s something for (((a))):
# Treetop, not Ruby
grammar ParenLanguage
rule nested_parens
'(' nested_parens ')' / [a-z]
end
end
# use in Ruby like so
load_grammar 'paren_language'
parser = ParenLanguageParser.new
tree = parser.parse("(((a)))")
The tree above is an OO view of the parse.
Some livecoding
Let’s parse the language of arithmetic.
(5 + 2) * (10 - 5)
First, draw a tree over the thing you want to parse.
Here’s what I captured from what he livecode:
dir = File.dirname(__FILE__)
require "#{dir}/test_header"
load_grammar "#{dir}/aritmetic"
class ArithmeticGrammarTest < Test::Unit::TestCase
include GrammarTestHelper
def setup
@parser = ArithmeticParser.new
end
def test_numbers_simple
assert @parser.parse('0').success?
assert_equal 0, @parser.parse('0').eval
assert @parser.parse('123').success?
end
def test_numbers_use_helpers
assert 0, parse('0').eval
end
def test_variables
assert_equal 2, ... something ..
end
test_multiplicative
assert_equal 20, parse('x * 10').eval({'x' => 2})
assert_equal 4 * 3 * 2, parse('4 * 3 * 2 * 1').eval...
end
def test_additive
assert_equal 5 + 2 * 10 - 5, parse('5 + x * 10 - y').eval({'x' => 2, 'y' => 5})
end
def test_parentheses
assert_equal (5 + 2) * (10 - 5), parse('(5 + x) * (10 - y)').eval({'x' => 2, 'y' => 5})
end
end
# different file
grammar Arithmetic
rule primary
variable
/
number
/
'(' space additive space ')' {
eval(...)
}
end
rule space
' '*
end
rule additive
operand_1:multiplicative space additive_op space operand_2:additive {
def eval(env)
additive_op.apply(operand_1.eval(env), operand_2.eval(env))
end
}
/
primary
end
rule additive_op
'+'
end
rule multiplicative
operand_1:primary space '*' space operand_2:multiplicative {
def eval(env)
operand_1.eval(env) * operand_2.eval(env)
end
}
/
primary
end
rule variable
[a-z]+ {
def eval(env)
env[name]
end
def name
text_value
end
}
end
rule number
([1-9] [0-9]* / '0') {
def eval(env)
text_value.to_i
end
}
end
end
Note that we didn’t lex anywhere above, and that the stuff above is composable. Grammars can be opened up an have other Grammars included (include Arithmetic, then override some part of it!)).
[Just showed up a Turing-complete Lambda Calculus language parser in 132 lines]
Imagine (using each others PEGs):
grammar RubyWithSQLStrings
include Ruby
include SQL
rule expression
ruby_expression
end
rule ruby_string
quote sql_expression quote / super
end
end
We didn’t cover lookahead, but there’s both negative and positive. Here’s negative (a quote, a bunch of not quotes, followed by quote):
'"' (!'"' .)* '"'
Memoization makes all of this stuff work, although it wasn’t an option in the past.
Ryan Davis: Hurting Code for Fun and Profit
On Ruby Sadism, Asceticism, & Introspection.
Start with a story: Once upon a time, a developer went to a New Place. The New Place had legacy code (any code that you didn’t write yourself). Every piece of legacy code reference 5 other files and everything is a rats nest. The developer is mad. He does what is “right” and kills all of the people responsible.
OR: Developer finds the dependencies, the rats nest, and gets angry. But, this time he pulls out tools and instead of maiming the people, he hurts the code. He shows the code who is boss.
Photo by candescence
People will press charges when you hurt them, code won’t.
Why Hurt Code
Hurting code is fun, and may make your code cleaner, more readable, and easier to test. If you make fixing code fun, you’ll do it much more often. An obvious example of sadism is killing a bug by writing a new test.
For some reason, people love complexity. Asceticism is characterized by strict self-discipline. Test-first is an example of asceticism. YAGNI is an example of abstenstion. Resist indulgence! (needless complexity, overly-clever code, code that you don’t need right now, “technical debt”)
“A developer’s obligation is to make sure that the code as written makes the clearest possible statement as to how the solution was understood at the time of writing.” –Ward Cunningham
Introspection-oriented development
How to do it?
- Ask yourself constantly: How do I do better? How did I overlook that bug? Am I wrong?
- Improve yourself: read 1 nerd book per month (which is 12x industry average)
- c2.com & other wikis with smart people
- Get rid of high-flow mailing lists, meaningless blogs in feedreader, bad sites
- Grow: Learn a language a year, learn your tools much better, examine your habits, study something wierd
- Push yourself: Write lots; throw away; write more (they weren’t kidding when they said “practice makes perfect”)
- Push yourself more: Be competetive, challenge the status quo
- Feel: Have an opinion, have passion (zentest, flog & heckle all came from love) (image_science came from hate)
- Feedback: Figure out how to get better
Tools
Flog can help find code that will be hard to test and understand.
Coverage tools are good at finding gaping holes, but not anything about quality.
Heckle (“the most sadistic tools I’ve written”) mutates your implementation to make sure that your tests are good.