Wow Code, Such Read! (RubyConf Colombia)

@kwugirl Wow Code, Such Read! KWu Ruby Agent Engineer amaze
understand so power

@kwugirl the goal: get better at reading code

be fearless in diving into code you don’t know Edmond
Lau theeffectiveengineer.com

@kwugirl

@kwugirl 10.000 hours

@kwugirl 10.000 hours 250 weeks

@kwugirl 10.000 hours 250 weeks ~5 years!

@kwugirl productive struggling

@kwugirl code archaeology https://www.ﬂickr.com/photos/22134952@N04/2850397739

@kwugirl 2. remember your question 3. enlist help 1. see
the code

@kwugirl the problem

@kwugirl the problem connection.execute("EXPLAIN #{query}")

@kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE
"blogs"."id" = $1 LIMIT 1 with

@kwugirl { :sql=>  "SELECT \"blogs\".* FROM \"blogs\" WHERE \"blogs\".\"id \"
= $1 LIMIT 1", … :binds=> [[#<ActiveRecord::ConnectionAdapters::PostgreSQLColumn: 0x007fd13a879e58 @array=false, @cast_type=#<ActiveRecord::ConnectionAdapters::PostgreS QL::OID::Integer:0x007fd13a87afd8 @limit=nil, @precision=nil, @range=-2147483648...2147483648, @scale=nil>,…,42]] } ActiveSupport::Notifications.subscribe 'sql.active_record'

the code

@kwugirl

@kwugirl $ cd src/

@kwugirl $ cd src/ $ git clone [email protected]:rails/rails.git  $ cd
rails/

@kwugirl $ cd src/ $ git clone [email protected]:rails/rails.git  $ cd
rails/ $ git checkout v4.2.0

@kwugirl # Gemfile gem 'rails', '4.2.0'

@kwugirl # Gemfile # gem 'rails', '4.2.0' gem 'rails', :path
=> '../../src/rails'

@kwugirl @instrumenter.instrument( "sql.active_record", :sql => sql, :name => name, :connection_id
=> object_id, :statement_name => statement_name, :binds => binds) { yield } def log(sql, name = "SQL", binds = [], statement_name = nil) # active_record/connection_adapters/abstract_adapter.rb

@kwugirl def log(sql, name = "SQL", binds = [], statement_name
= nil) @instrumenter.instrument( "sql.active_record", :sql => sql, :name => name, :connection_id => object_id, :statement_name => statement_name, :binds => binds) { yield } puts "====== HELLO IS IT ME YOU'RE LOOKING FOR?!!?? ======" # active_record/connection_adapters/abstract_adapter.rb

@kwugirl git blame (can be) your friend

the code

@kwugirl don’t get lost

@kwugirl don’t get lost learn one thing at a time

@kwugirl don’t get lost learn one thing at a time
what are your unknowns?

@kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE
"blogs"."id" = $1 LIMIT 1 with

the code

@kwugirl pair programming

@kwugirl pair programming ¿?¿?¿?¿?¿? ¿?¿?¿?¿?¿? ¿?¿?¿?¿?¿?

@kwugirl

@kwugirl What are you looking for?

@kwugirl What are you looking for? Why?

@kwugirl What are you looking for? Why? How did you
know to look there?

@kwugirl Kernel#caller

@kwugirl active_record/connection_adapters/postgresql_adapter.rb:601:in èxec_cache' active_record/connection_adapters/postgresql_adapter.rb:585:in èxecute_and_clear' active_record/connection_adapters/postgresql/database_statements.rb:161:in èxec_query' active_record/connection_adapters/abstract/database_statements.rb:341:in `select' active_record/connection_adapters/abstract/database_statements.rb:37:in
`select_all' active_record/connection_adapters/abstract/query_cache.rb:70:in `select_all' active_record/querying.rb:39:in `find_by_sql' active_record/relation.rb:639:in èxec_queries' active_record/relation.rb:514:in `load' active_record/relation.rb:243:in `to_a' active_record/relation.rb:617:in `pretty_print' Kernel#caller

@kwugirl Method#source_location

@kwugirl Method#source_location $ bundle exec rails console

@kwugirl Method#source_location $ bundle exec rails console irb(main):001:0> method(:try).source_location

@kwugirl Method#source_location $ bundle exec rails console irb(main):001:0> method(:try).source_location =>
["/…/active_support/core_ext/object/try.rb", 62]

@kwugirl method_deﬁned? RubyTapas #439 “Method Search”

@kwugirl method_deﬁned? $ ObjectSpace.each_object(Class).select{|c| c.singleton_class.method_defined?(:try_convert) } => [File, IO, Regexp,
Hash, Array, String] RubyTapas #439 “Method Search”

@kwugirl the solution connection.exec_query("EXPLAIN #{statement.sql}", "Explain #{statement.name}", statement.binds) wow beauty
wonder

@kwugirl success!!1!one!!

@kwugirl success!!1!one!! $1

@kwugirl success!!1!one!! $1 }Explain plan

@kwugirl success!!1!one!! released in 3.15.2 $1 }Explain plan

the code

@kwugirl reading ruby source

@kwugirl gentle intro

@kwugirl which ﬁles?

@kwugirl github.com/ruby/ruby

@kwugirl github.com/ruby/ruby “trunk” not “master”

@kwugirl pretty ﬂat directory

@kwugirl std library in lib/

@kwugirl extension.rdoc

@kwugirl parse.y

@kwugirl other helpful points

@kwugirl other helpful points rb_

@kwugirl other helpful points rb_ regex search with ^ to
ﬁnd method deﬁnition

@kwugirl other helpful points rb_ regex search with ^ to
ﬁnd method deﬁnition comments

@kwugirl bugs.ruby-lang.org

@kwugirl resources

@kwugirl resources readingcodegood.com

@kwugirl resources readingcodegood.com schneems' talk “Dissecting Ruby with Ruby”

@kwugirl resources readingcodegood.com schneems' talk “Dissecting Ruby with Ruby” schneems.com/2016/01/25/ruby-debugging-magic-
cheat-sheet.html  tenderlovemaking.com/2016/02/05/i-am-a-puts- debuggerer.html

@kwugirl resources

@kwugirl resources Jason Clark’s talk “GDB: A Gentle Intro”

@kwugirl resources Jason Clark’s talk “GDB: A Gentle Intro” Hsing-Hui
Hsu’s talk “Time ﬂies like an arrow, fruit ﬂies like a banana”

Hsu’s talk “Time ﬂies like an arrow, fruit ﬂies like a banana” Ruby Under A Microscope

Hsu’s talk “Time flies like an arrow, fruit flies like a banana” Ruby Under A Microscope Definitive Guide to Ruby’s C API:   https://silverhammermba.github.io/emberb/c/

@kwugirl Julia Evans jvns.ca

@kwugirl Net::HTTP is maybe 2000 lines of code, not including
comments. Julia Evans jvns.ca

comments. It has ~1000 lines of comments… Julia Evans jvns.ca

comments. It has ~1000 lines of comments… I can read 2000 lines of code, Julia Evans jvns.ca

comments. It has ~1000 lines of comments… I can read 2000 lines of code, mostly! Julia Evans jvns.ca

@kwugirl ¿?s

@kwugirl appendix

@kwugirl doge The White Rabbit, Alice in Wonderland sad Keanu
pear/pair programming Lionel Richie + Where’s Waldo !!1!one!! the “!1” phenomenon breadﬁsh Slurms MacKenzie, Futurama

@kwugirl This document and the information herein (including any information
that may be incorporated by reference) is provided for informational purposes only and should not be construed as an offer, commitment, promise or obligation on behalf of New Relic, Inc. (“New Relic”) to sell securities or deliver any product, material, code, functionality, or other feature. Any information provided hereby is proprietary to New Relic and may not be replicated or disclosed without New Relic’s express written permission. Such information may contain forward-looking statements within the meaning of federal securities laws. Any statement that is not a historical fact or refers to expectations, projections, future plans, objectives, estimates, goals, or other characterizations of future events is a forward-looking statement. These forward-looking statements can often be identified as such because the context of the statement will include words such as “believes,” “anticipates,” “expects” or words of similar import. Actual results may differ materially from those expressed in these forward-looking statements, which speak only as of the date hereof, and are subject to change at any time without notice. Existing and prospective investors, customers and other third parties transacting business with New Relic are cautioned not to place undue reliance on this forward-looking information. The achievement or success of the matters covered by such forward-looking statements are based on New Relic’s current assumptions, expectations, and beliefs and are subject to substantial risks, uncertainties, assumptions, and changes in circumstances that may cause the actual results, performance, or achievements to differ materially from those expressed or implied in any forward-looking statement. Further information on factors that could affect such forward-looking statements is included in the filings we make with the SEC from time to time. Copies of these documents may be obtained by visiting New Relic’s Investor Relations website at ir.newrelic.com or the SEC’s website at www.sec.gov. New Relic assumes no obligation and does not intend to update these forward-looking statements, except as required by law. New Relic makes no warranties, expressed or implied, in this document or otherwise, with respect to the information provided.

Wow Code, Such Read! (RubyConf Colombia)

Wow Code, Such Read! (RubyConf Colombia)

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