Confident-Ruby by Author, Unknown -- Read -- Imperial Library of Trantor

Index

Introduction

Ruby meets the real world Confident code A good story, poorly told Code as narrative The four parts of a method How this book is structured 3.times { rejoice! }

Performing Work

Sending a strong message Importing purchase records Identifying the messages Identifying the roles Avoiding the MacGyver method Letting language be constrained by the system Talk like a duck Herding ducks

Collecting Input

Introduction to collecting input

Indirect inputs From Roles to Objects Guard the borders, not the hinterlands

Use built-in conversion protocols

Indications Synopsis Rationale Example: Announcing winners Example: ConfigFile A list of standard conversion methods Explicit and implicit conversions If you know what you want, ask for it Conclusion

Conditionally call conversion methods

Indications Synopsis Rationale Example: opening files Violating duck typing, just this once Conclusion

Define your own conversion protocols

Indications Synopsis Rationale Example: Accepting either a Point or a pair Conclusion

Define conversions to user-defined types

Indications Synopsis Rationale Example: Converting feet to meters Conclusion

Use built-in conversion functions

Indications Synopsis Rationale Example: Pretty-printing numbers Hash.[] Conclusion

Use the Array() conversion function to array-ify inputs

Indications Synopsis Rationale Example: Accepting one or many arguments Conclusion

Define conversion functions

Indications Synopsis Rationale Example: A conversion function for 2D points About module_function Combining conversion protocols and conversion functions Lambdas as case conditions Conclusion

Replace "string typing" with classes

Indications Synopsis Rationale Example: Traffic light states Conclusion

Wrap collaborators in Adapters

Indications Synopsis Rationale Example: Logging to IRC Conclusion

Use transparent adapters to gradually introduce abstraction

Indications Synopsis Rationale Example: Logging to IRC, again Conclusion

Reject unworkable values with preconditions

Indications Synopsis Rationale Example: Employee hire dates Executable documentation Conclusion

Use #fetch to assert the presence of Hash keys

Indications Synopsis Rationale Example: A wrapper for useradd(8) Go #fetch Customizing #fetch Conclusion

Use #fetch for defaults

Indications Synopsis Rationale Example: Optionally receiving a logger Reusable #fetch blocks Two-argument #fetch Conclusion

Document assumptions with assertions

Indications Synopsis Rationale Example: Importing bank transactions Conclusion

Handle special cases with a Guard Clause

Indications Synopsis Rationale Example: Adding a "quiet mode" flag Put the return first Conclusion

Represent special cases as objects

Indications Synopsis Rationale Example: A guest user Representing current user as a special case object Making the change incrementally Keeping the special case synchronized Conclusion

Represent do-nothing cases as null objects

Indications Synopsis Rationale Generic Null Object Crossing the event horizon Making Null Objects false-y. Conclusion

Substitute a benign value for nil

Indications Synopsis Rationale Example: Displaying member location data If you're benign, you'll be fine! Conclusion

Use symbols as placeholder objects

Indications Synopsis Rationale Example: Optionally authenticating with a web service The trouble with nil Symbolic placeholders Conclusion

Bundle arguments into parameter objects

Indications Synopsis Rationale Parameter Object review Adding optional parameters Conclusion

Yield a parameter builder object

Indications Synopsis Rationale Example: a convenience API for drawing points Net/HTTP vs. Faraday Yielding a builder Conclusion

Receive policies instead of data

Indications Synopsis Rationale Example: Deleting files Conclusion

Delivering Results

Write total functions

Indications Synopsis Rationale Example: Searching a list of words Conclusion

Call back instead of returning

Indications Synopsis Rationale Example Conclusion

Represent failure with a benign value

Indications Synopsis Rationale Example: Rendering tweets in a sidebar Conclusion

Represent failure with a special case object

Indications Synopsis Rationale Example: A guest user Conclusion

Return a status object

Indications Synopsis Rationale Example: Reporting the outcome of an import Conclusion

Yield a status object

Indications Synopsis Rationale Example: Yielding the outcome of an import Testing a yielded status object Conclusion

Signal early termination with throw

Indications Synopsis Example: Ending HTML parsing part way through a document Conclusion

Handling Failure

Prefer top-level rescue clause

Indications Synopsis Rationale Example Conclusion

Use checked methods for risky operations

Indications Synopsis Rationale Example Onward to Adapters Conclusion

Use bouncer methods

Indications Synopsis Rationale Example: Checking for child process status Conclusion

Refactoring for Confidence

MetricFu

Location HotspotAnalyzedProblems Ranking

Stringer

Parting Words

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