Frozenrails2011

@josephwilk

Tuesday, 20 September 11

Joseph Wilk

Limited Red
Joseph Wilk

Limited Red
Oh crap

Joseph Wilk

Work In Progress


Context Switching is
Expensive


Small Batch sizes
Large
batches

Small
batches


Red == Work in Progress


1 day

1.5 day

2 day


Why is Red Bad?


Limit Red

Measure Red

Visualise Red

Learn

Are we
Professionals?


Joseph Wilk
PAIRING
RED TIME

TESTING
REFACTORING


Measuring &
Visualising Red


Limited Red
Learn and adapt from test metrics


Industrial Logic

Fighting
Red


Patterns
‣Parallel Change
‣Narrowed Change
‣Sequence Change
‣Graceful Retreat
‣Piecemeal Change
‣Gradual Change
‣Evolved Target
‣Unified Methods Joshua
Kerievsky

Parallel Change
class ImageResizer

def resize(x,y)
...
end

end


Parallel Change
class ImageResizer
include ThumbResizer
end

module ThumbResizer
def resize(x,y)
...
end
end


Ship it

But....


class ImageResizer

Parallel Change
if FeatureFlipper.active?(:fast_resizer)
include FastThumbResizer
else
include ThumbResizer
end
end

module ThumbResizer
def resize(x,y)
...
end
end

module FastThumbResizer
def resize(x,y)
...
end
end


But.. Both
versions!!!


Parallel Change
class ImageResizer
include FastThumbResizer
end

module FastThumbResizer
def resize(x,y)
...
end
end


Narrowed Change
<%- if @game.player?(@active_user) &&
@black_player.present? &&
@white_player.present? %>
<%= render :template => 'messaging' %>
<%- end %>

<%- if @game.player?(@active_user) &&
@white_player.present? %>
<%- end %>


Narrowed Change
<%- game_presenter.show_messaging? do %>
<%- end %>

class GamePresenter
def initialize(game, black_payer, white_player)
@game, @black_player, @white_player = game,
black_player, white_player
end

def show_messaging?(&block)
messaging_should_be_visible = @game.player?(@user) &&
@white_player.present?

yield block if messaging_should_be_visible
end
end

Narrowed Change
<%- game_presenter.show_messaging? do %>
<%- end %>

class GamePresenter
def initialize(game, black_payer, white_player)
@game, @black_player, @white_player = game,
black_player, white_player
end

def show_messaging?(&block)
messaging_should_be_visible= @game.human_player?(@user)
yield block if messaging_should_be_visible
end
end


Sequence Change

Remove Narrowed Extract
control flag change method


Sequence Change

Narrowed Remove Extract
change control flag method


Graceful Retreat
Please step away from the Yak... Slowly

Shave?


http://www.refactoring.com/catalog/index.html

Learning more from Red
‣ Smart Continuous integration
‣ Failure rate
‣ Performance
‣ Flickering


Evil hat


More Books!


“To measure is to know” Lord Kelvin


Kiitos
@josephwilk
joe@josephwilk.net


Kiitos
@josephwilk
joe@josephwilk.net

Green


Kiitos
@josephwilk
joe@josephwilk.net

Ship it
Green

Frozenrails2011

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