Active SupportCore Extensions (3)

ROR lab. DD-1- The 3rd round -

April 13, 2013

Hyoseong Choi

Ext. to Class• class_attribute

active_support/core_ext/class/attribute.rb

class A  class_attribute :xend class B < A; end class C < B; end A.x = :aB.x # => :aC.x # => :a

B.x = :bA.x # => :aC.x # => :b C.x = :cA.x # => :aB.x # => :b

one or more inheritable class attributes that can be overridden at any level down the hierarchy

Ext. to Class• class_inheritable_accessor, _reader, _writer

active_support/core_ext/class/inheritable_attributes.rb

module ActionController  class Base    # FIXME: REVISE/SIMPLIFY THIS COMMENT.    # The value of allow_forgery_protection is inherited,    # but its value in a particular class does not affect    # the value in the rest of the controllers hierarchy.    class_inheritable_accessor :allow_forgery_protection  endend

: deprecated ➜ class_attribute instead

accessors for class-level data which is inherited but not shared with children

class C; endC.subclasses # => [] class B < C; endC.subclasses # => [B] class A < B; endC.subclasses # => [B] class D < C; endC.subclasses # => [B, D]

Ext. to Class• subclasses

active_support/core_ext/class/subclasses.rb

C

B

A

D

Ext. to Class• descendants

active_support/core_ext/class/subclasses.rb

class C; endC.descendants # => [] class B < C; endC.descendants # => [B] class A < B; endC.descendants # => [B, A] class D < C; endC.descendants # => [B, A, D]

C

B

A

D

Ext. to String• Strings “(html) unsafe” by default since Rails3

"".html_safe? # => false

s = "".html_safes.html_safe? # => true

• html_safe no escaping

s = "<script>...</script>".html_safes.html_safe? # => trues            # => "<script>...</script>"

active_support/core_ext/string/output_safety.rb

Ext. to String• html_safe

active_support/core_ext/string/output_safety.rb

<%= raw @cms.current_template %>

<%== @cms.current_template %>

def raw(stringish)  stringish.to_s.html_safeend

Ext. to String• squish, squish!

active_support/core_ext/string/filters.rb

" \n  foo\n\r \t bar \n".squish # => "foo bar"

Ext. to String• truncate

active_support/core_ext/string/filters.rb

"Oh dear! Oh dear! I shall be late!".truncate(20)# => "Oh dear! Oh dear!..."

"Oh dear! Oh dear! I shall be late!".truncate(20, :omission => '&hellip;')# => "Oh dear! Oh &hellip;" …

"Oh dear! Oh dear! I shall be late!".truncate(18)# => "Oh dear! Oh dea...""Oh dear! Oh dear! I shall be late!".truncate(18, :separator => ' ')# => "Oh dear! Oh..."

Ext. to String• Output safety - inquiry

active_support/core_ext/string/inquiry.rb

"production".inquiry.production? # => true"active".inquiry.inactive?       # => false

a StringInquirer object

Ext. to String• Output safety - Key-based interpolation

active_support/core_ext/string/interpolation.rb

"Total is %<total>.02f" % {:total => 43.1}  # => Total is 43.10

"I say %{foo}" % {:foo => "wadus"}          # => "I say wadus"

"I say %{woo}" % {:foo => "wadus"}          # => KeyError

Ext. to String• Output safety - start_with? / ends_with?

active_support/core_ext/string/starts_ends_with.rb

"foo".starts_with?("f") # => true"foo".ends_with?("o")   # => true

Ext. to String• Output safety - strip_heredoc

active_support/core_ext/string/strip.rb

if options[:usage]  puts <<-USAGE.strip_heredoc    This command does such and such.     Supported options are:      -h         This message      ...  USAGEend

Ext. to String• Access - at(position)

active_support/core_ext/string/access.rb

"hello".at(0)  # => "h""hello".at(4)  # => "o""hello".at(-1) # => "o""hello".at(10) # => ERROR if < 1.9, nil in 1.9

Ext. to String• Access - from(position)

active_support/core_ext/string/access.rb

"hello".from(0)  # => "hello""hello".from(2)  # => "llo""hello".from(-2) # => "lo""hello".from(10) # => "" if < 1.9, nil in 1.9

Ext. to String• Access - to(position)

active_support/core_ext/string/access.rb

"hello".to(0)  # => "h""hello".to(2)  # => "hel""hello".to(-2) # => "hell""hello".to(10) # => "hello"

Ext. to String• Access - first/last

active_support/core_ext/string/access.rb

str.first(n) or str.to(n-1)

str.last(n) or str.from(-n)

Ext. to String• Inflections

active_support/core_ext/string/inflections.rb

• pluralize

• singularize

• camerlize

• underscore

• titleize

• dasherize

• demodulize

• deconstantize

• parameterize

• tableize

• classify

• constantize

• humanize

• foreign_key

ROR Lab.

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