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Brandon Keepers
Lone Star Ruby Conference V
August 12, 2011
BAD
the world runs on
software
Ordered List
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@bkeepers
I
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opensoul.org
I
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group therapy
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pride
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craftsman
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art
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I
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get.harmonyapp.com
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get.gaug.es
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speakerdeck.com
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I — GOOD CODE!
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not perfect
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:(
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HAS NOT
IMPLODED
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HAS NOT
IMPLODED yet
^
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RUNS
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in spite of
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because of
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bad software
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pragmatism
perfection
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What is good software?
How does it go bad?
How do we build better software?
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good software
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“
Good software meets the
present objective at an
acceptable cost without
incurring an unacceptable
amount of future risk.
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adequacy
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!mediocrity
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objective
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software
!=
code
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“
Zach Dennis
Mutually Human Software
People fail to realize that
quality is merely a property of
the code that exists, not the
reason for its existence.
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users don’t care
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“
Scott Berkun
We’re frustrated most in
life by things that come
close to our deepest
needs, but don’t deliver.
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cost
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“
Ray Yeargin
Virtually all of the cost of
software development is,
directly and indirectly, the
cost of design.
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Production
almost zero of
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$$$$
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$$$
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$$
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$
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risk
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!science
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‑Risk
‐Cost
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What is good software?
How does it go bad?
How do we build better software?
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entropy
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“
The Pragmatic Programmer
While software development
is immune from almost all
physical laws, entropy hits
us hard.
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why?
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software is
malleable
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software is
complex
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rake stats
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2.5 million parts
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software is
immature
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software is
opaque
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software is
durable
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What is good software?
How does it go bad?
How do we build better software?
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better software?
how do we build
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talk to your users
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automated testing
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insurance policy
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automation
computers are good at
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DRY
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refactoring
small, incremental
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What is good software?
How does it go bad?
How do we build better software?
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Examples
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method_missing
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class NilClass
def method_missing(method, *args)
nil
end
end
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>> nil.foo.bar
=> nil
>> nil + 5
=> nil
>> 5 + nil
TypeError: coerce must return [x, y]
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performance
maintenance
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def to_xml(options={})
root_tag = options.fetch(:root, 'game')
instruct = options[:skip_instruct] ? '' : XML_INSTRUCT
# …
# gather up a bunch of variables
# …
<<-EOF
#{instruct}
<#{root_tag}>
#{id}
#{current_move_user_id}
current-move-user-id>
#{created_by_user_id}
created-by-user-id>
0
#{is_matchmaking}
#{was_matchmaking}
#{moves_count}
#{random_seed}
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#{instruct}
<#{root_tag}>
#{id}
#{current_move_user_id}
current-move-user-id>
#{created_by_user_id}
created-by-user-id>
0
#{is_matchmaking}
#{was_matchmaking}
#{moves_count}
#{random_seed}
#{client_version}
#{created_at.try(:xmlschema)}
created-at>
#{users_xml}
#{current_user_xml}
#{moves_xml}
#{chats_xml}
#{root_tag}>
EOF
end
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commit fa779d9c2d1214e43ff497f386b51ebf3708346e
Author: Brandon Keepers
Date: Wed Sep 22 17:08:38 2010 -0400
First attempt at getting embedded callbacks working
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def create_or_update
run_callbacks(:before_save)
if result = super
run_callbacks(:after_save)
end
result
end
Rails 2
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def create_or_update
run_callbacks(:save) { super }
end
Rails 3
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def run_callbacks(kind, options={}, &block)
self.embedded_associations.each do |association|
self.send(association.name).run_callbacks(
kind, options, &block
)
end
end
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def run_callbacks(callback, &block)
embedded_docs = []
embedded_associations.each do |association|
embedded_docs += association.target
end
block = embedded_docs.inject(block) do |chain, doc|
if doc.class.respond_to?("_#{callback}_callbacks")
lambda { doc.run_callbacks(callback, &chain) }
else
chain
end
end
super callback, &block
end
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SystemStackError: stack level too deep
from mongo_mapper/plugins/embedded_callbacks.rb:23:in `run_callbacks'
from activesupport-3.0.9/lib/active_support/callbacks.rb:414:in
`_run_create_callbacks'
from activesupport-3.0.9/lib/active_support/callbacks.rb:94:in `send'
from activesupport-3.0.9/lib/active_support/callbacks.rb:94:in
`run_callbacks'
from mongo_mapper/plugins/embedded_callbacks.rb:28:in `run_callbacks'
from mongo_mapper/plugins/embedded_callbacks.rb:23:in `run_callbacks'
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now what?
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pragmatic
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software is design
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embrace constraints
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engineering is design
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craftsmanship is design
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“
Glen Vanderburg
Sometimes you have to move
ahead with weak evidence and
weak conclusions because you
don't have time to prove them.
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opportunity costs
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be pragmatic
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No content
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“
Ed Yourdon
You can discipline yourself to write
software that's good enough—good
enough for your users, for future
maintainers, for your own peace of
mind. You'll find that you are more
productive and your users are happier.
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Ordered List
Thank you!
[email protected]
Brandon Keepers
Lone Star Ruby Conference V
August 12, 2011
@bkeepers
http://spkr8.com/t/7829
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Credits
Power lines - http://www.flickr.com/photos/viamoi/3339707547/
House of cards - http://www.flickr.com/photos/gibbons/2294374741/
Dentists office - http://www.flickr.com/photos/cmdrcord/4996672560/
Broken chair - http://www.flickr.com/photos/gorbould/3004789912/
Schematics - http://www.flickr.com/photos/nicklockey/4547935355/
Engineers - http://www.flickr.com/photos/seattlemunicipalarchives/4818952324/
Black box - http://goldberg.berkeley.edu/art/big-images/