How to decorate all similar methods in Ruby?

Here is my class:

class Book

  def read

     # something

  end

end

And another one:

class Magazine

  def read

     # something

  end

end

Now, I want to decorate both read methods in these two classes. I want them both to print "hello" right before they start working. How do I do that? I suspect, I need to use mixins, but can't figure out exactly how.

asked Nov 21 '18 at 13:07

yegor256

56k87365508

2

Ah, it's a pity that your bot is not giving out rewards here :)

– Sergio Tulentsev
Nov 21 '18 at 13:51

add a comment |

Here is my class:

class Book

  def read

     # something

  end

end

And another one:

class Magazine

  def read

     # something

  end

end

asked Nov 21 '18 at 13:07

yegor256

56k87365508

2

Ah, it's a pity that your bot is not giving out rewards here :)

– Sergio Tulentsev
Nov 21 '18 at 13:51

add a comment |

Here is my class:

class Book

  def read

     # something

  end

end

And another one:

class Magazine

  def read

     # something

  end

end

asked Nov 21 '18 at 13:07

yegor256

56k87365508

Here is my class:

class Book

  def read

     # something

  end

end

And another one:

class Magazine

  def read

     # something

  end

end

ruby

asked Nov 21 '18 at 13:07

yegor256

56k87365508

asked Nov 21 '18 at 13:07

yegor256

56k87365508

asked Nov 21 '18 at 13:07

yegor256

56k87365508

asked Nov 21 '18 at 13:07

yegor256

56k87365508

asked Nov 21 '18 at 13:07

yegor256

56k87365508

2

Ah, it's a pity that your bot is not giving out rewards here :)

– Sergio Tulentsev
Nov 21 '18 at 13:51

add a comment |

2

Ah, it's a pity that your bot is not giving out rewards here :)

– Sergio Tulentsev
Nov 21 '18 at 13:51

Ah, it's a pity that your bot is not giving out rewards here :)

– Sergio Tulentsev
Nov 21 '18 at 13:51

add a comment |

2 Answers
2

active

oldest

votes

You can prepend module:

module Decorator

  def read

    puts "hello"

    super

  end

end



class Book

  prepend Decorator



  def read

    puts "bye"

  end

end



class Magazine

  prepend Decorator



  def read

    puts "cya"

  end

end



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

As well there is more clean way to do this kind of modifications with refinements:

class Book

  def read

    puts "bye"

  end

end



class Magazine

  def read

    puts "cya"

  end

end



module Decorator

  def read

    puts "hello"

    super

  end

end



module DecoratedBook

  refine Book do

    prepend Decorator

  end

end



module DecoratedMagazine

  refine Magazine do

    prepend Decorator

  end

end



using DecoratedBook

using DecoratedMagazine



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

Notice: this code may not run in irb.

Also you can do it right in the runtime:

module Decorator

  def read

    puts "hello"

    super

  end

end



[Book, Magazine].each do |klass|

  klass.prepend Decorator

end



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

edited Nov 21 '18 at 14:17

answered Nov 21 '18 at 13:37

jarosluv

885

You probably want to call super in that decorator

– Sergio Tulentsev
Nov 21 '18 at 13:39

You're right. I've got the original question wrong before. Thank you.

– jarosluv
Nov 21 '18 at 13:45

1

Also why class_eval? Can simply do klass.prepend Decorator

– Sergio Tulentsev
Nov 21 '18 at 13:50

1

This is stale part of code from my previous version of answer, that I've just fixed. Generally you're totally right again. Thank you :)

– jarosluv
Nov 21 '18 at 14:22

add a comment |

May be you want something as:

class ReaderDecorator

  def initialize(obj)

    @obj = obj

  end



  def read

    puts 'Hello'

    @obj.read

  end

end



ReaderDecorator.new(Book.new).read

ReaderDecorator.new(Magazine.new).read

answered Nov 21 '18 at 13:39

vk26

585

I think this is the correct example of "decorator pattern".

– Kimmo Lehto
Nov 21 '18 at 13:49

1

@KimmoLehto: depends. For one thing, other methods are not proxied here (original object's API, if it were specified, is not reflected fully). And some clients may do type checks, so you might want your decorated object still be_a? the same type.

– Sergio Tulentsev
Nov 21 '18 at 13:55

@SergioTulentsev yes, with class ReaderDecorator < SimpleDelegator it would be better. The question does have the keyword "decorate", so an answer with an actual "decorator" is fitting.

– Kimmo Lehto
Nov 22 '18 at 7:12

@KimmoLehto "actual" as in "as described by gang of four"? Their decorator implements the interface (maintains both api surface and type checks). Anyway, what I was trying to say is there are flavors of decorators. Who's to say which one of them is the "real" one? :)

– Sergio Tulentsev
Nov 22 '18 at 17:03

add a comment |

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2 Answers
2

active

oldest

votes

2 Answers
2

active

oldest

votes

You can prepend module:

module Decorator

  def read

    puts "hello"

    super

  end

end



class Book

  prepend Decorator



  def read

    puts "bye"

  end

end



class Magazine

  prepend Decorator



  def read

    puts "cya"

  end

end



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

As well there is more clean way to do this kind of modifications with refinements:

class Book

  def read

    puts "bye"

  end

end



class Magazine

  def read

    puts "cya"

  end

end



module Decorator

  def read

    puts "hello"

    super

  end

end



module DecoratedBook

  refine Book do

    prepend Decorator

  end

end



module DecoratedMagazine

  refine Magazine do

    prepend Decorator

  end

end



using DecoratedBook

using DecoratedMagazine



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

Notice: this code may not run in irb.

Also you can do it right in the runtime:

module Decorator

  def read

    puts "hello"

    super

  end

end



[Book, Magazine].each do |klass|

  klass.prepend Decorator

end



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

edited Nov 21 '18 at 14:17

answered Nov 21 '18 at 13:37

jarosluv

885

You probably want to call super in that decorator

– Sergio Tulentsev
Nov 21 '18 at 13:39

You're right. I've got the original question wrong before. Thank you.

– jarosluv
Nov 21 '18 at 13:45

1

Also why class_eval? Can simply do klass.prepend Decorator

– Sergio Tulentsev
Nov 21 '18 at 13:50

1

This is stale part of code from my previous version of answer, that I've just fixed. Generally you're totally right again. Thank you :)

– jarosluv
Nov 21 '18 at 14:22

add a comment |

You can prepend module:

module Decorator

  def read

    puts "hello"

    super

  end

end



class Book

  prepend Decorator



  def read

    puts "bye"

  end

end



class Magazine

  prepend Decorator



  def read

    puts "cya"

  end

end



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

As well there is more clean way to do this kind of modifications with refinements:

class Book

  def read

    puts "bye"

  end

end



class Magazine

  def read

    puts "cya"

  end

end



module Decorator

  def read

    puts "hello"

    super

  end

end



module DecoratedBook

  refine Book do

    prepend Decorator

  end

end



module DecoratedMagazine

  refine Magazine do

    prepend Decorator

  end

end



using DecoratedBook

using DecoratedMagazine



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

Notice: this code may not run in irb.

Also you can do it right in the runtime:

module Decorator

  def read

    puts "hello"

    super

  end

end



[Book, Magazine].each do |klass|

  klass.prepend Decorator

end



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

edited Nov 21 '18 at 14:17

answered Nov 21 '18 at 13:37

jarosluv

885

You probably want to call super in that decorator

– Sergio Tulentsev
Nov 21 '18 at 13:39

You're right. I've got the original question wrong before. Thank you.

– jarosluv
Nov 21 '18 at 13:45

1

Also why class_eval? Can simply do klass.prepend Decorator

– Sergio Tulentsev
Nov 21 '18 at 13:50

1

This is stale part of code from my previous version of answer, that I've just fixed. Generally you're totally right again. Thank you :)

– jarosluv
Nov 21 '18 at 14:22

add a comment |

You can prepend module:

module Decorator

  def read

    puts "hello"

    super

  end

end



class Book

  prepend Decorator



  def read

    puts "bye"

  end

end



class Magazine

  prepend Decorator



  def read

    puts "cya"

  end

end



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

As well there is more clean way to do this kind of modifications with refinements:

class Book

  def read

    puts "bye"

  end

end



class Magazine

  def read

    puts "cya"

  end

end



module Decorator

  def read

    puts "hello"

    super

  end

end



module DecoratedBook

  refine Book do

    prepend Decorator

  end

end



module DecoratedMagazine

  refine Magazine do

    prepend Decorator

  end

end



using DecoratedBook

using DecoratedMagazine



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

Notice: this code may not run in irb.

Also you can do it right in the runtime:

module Decorator

  def read

    puts "hello"

    super

  end

end



[Book, Magazine].each do |klass|

  klass.prepend Decorator

end



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

edited Nov 21 '18 at 14:17

answered Nov 21 '18 at 13:37

jarosluv

885

You can prepend module:

module Decorator

  def read

    puts "hello"

    super

  end

end



class Book

  prepend Decorator



  def read

    puts "bye"

  end

end



class Magazine

  prepend Decorator



  def read

    puts "cya"

  end

end



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

As well there is more clean way to do this kind of modifications with refinements:

class Book

  def read

    puts "bye"

  end

end



class Magazine

  def read

    puts "cya"

  end

end



module Decorator

  def read

    puts "hello"

    super

  end

end



module DecoratedBook

  refine Book do

    prepend Decorator

  end

end



module DecoratedMagazine

  refine Magazine do

    prepend Decorator

  end

end



using DecoratedBook

using DecoratedMagazine



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

Notice: this code may not run in irb.

Also you can do it right in the runtime:

module Decorator

  def read

    puts "hello"

    super

  end

end



[Book, Magazine].each do |klass|

  klass.prepend Decorator

end



Book.new.read 

# "hello"

# "bye"



Magazine.new.read

# "hello"

# "cya"

edited Nov 21 '18 at 14:17

answered Nov 21 '18 at 13:37

jarosluv

885

edited Nov 21 '18 at 14:17

answered Nov 21 '18 at 13:37

jarosluv

885

answered Nov 21 '18 at 13:37

jarosluv

885

answered Nov 21 '18 at 13:37

jarosluv

885

You probably want to call super in that decorator

– Sergio Tulentsev
Nov 21 '18 at 13:39

You're right. I've got the original question wrong before. Thank you.

– jarosluv
Nov 21 '18 at 13:45

1

Also why class_eval? Can simply do klass.prepend Decorator

– Sergio Tulentsev
Nov 21 '18 at 13:50

1

This is stale part of code from my previous version of answer, that I've just fixed. Generally you're totally right again. Thank you :)

– jarosluv
Nov 21 '18 at 14:22

add a comment |

You probably want to call super in that decorator

– Sergio Tulentsev
Nov 21 '18 at 13:39

You're right. I've got the original question wrong before. Thank you.

– jarosluv
Nov 21 '18 at 13:45

1

Also why class_eval? Can simply do klass.prepend Decorator

– Sergio Tulentsev
Nov 21 '18 at 13:50

1

This is stale part of code from my previous version of answer, that I've just fixed. Generally you're totally right again. Thank you :)

– jarosluv
Nov 21 '18 at 14:22

You probably want to call super in that decorator

– Sergio Tulentsev
Nov 21 '18 at 13:39

You're right. I've got the original question wrong before. Thank you.

– jarosluv
Nov 21 '18 at 13:45

Also why class_eval? Can simply do klass.prepend Decorator

– Sergio Tulentsev
Nov 21 '18 at 13:50

This is stale part of code from my previous version of answer, that I've just fixed. Generally you're totally right again. Thank you :)

– jarosluv
Nov 21 '18 at 14:22

add a comment |

May be you want something as:

class ReaderDecorator

  def initialize(obj)

    @obj = obj

  end



  def read

    puts 'Hello'

    @obj.read

  end

end



ReaderDecorator.new(Book.new).read

ReaderDecorator.new(Magazine.new).read

answered Nov 21 '18 at 13:39

vk26

585

I think this is the correct example of "decorator pattern".

– Kimmo Lehto
Nov 21 '18 at 13:49

1

@KimmoLehto: depends. For one thing, other methods are not proxied here (original object's API, if it were specified, is not reflected fully). And some clients may do type checks, so you might want your decorated object still be_a? the same type.

– Sergio Tulentsev
Nov 21 '18 at 13:55

@SergioTulentsev yes, with class ReaderDecorator < SimpleDelegator it would be better. The question does have the keyword "decorate", so an answer with an actual "decorator" is fitting.

– Kimmo Lehto
Nov 22 '18 at 7:12

@KimmoLehto "actual" as in "as described by gang of four"? Their decorator implements the interface (maintains both api surface and type checks). Anyway, what I was trying to say is there are flavors of decorators. Who's to say which one of them is the "real" one? :)

– Sergio Tulentsev
Nov 22 '18 at 17:03

add a comment |

May be you want something as:

class ReaderDecorator

  def initialize(obj)

    @obj = obj

  end



  def read

    puts 'Hello'

    @obj.read

  end

end



ReaderDecorator.new(Book.new).read

ReaderDecorator.new(Magazine.new).read

answered Nov 21 '18 at 13:39

vk26

585

I think this is the correct example of "decorator pattern".

– Kimmo Lehto
Nov 21 '18 at 13:49

1

@KimmoLehto: depends. For one thing, other methods are not proxied here (original object's API, if it were specified, is not reflected fully). And some clients may do type checks, so you might want your decorated object still be_a? the same type.

– Sergio Tulentsev
Nov 21 '18 at 13:55

@SergioTulentsev yes, with class ReaderDecorator < SimpleDelegator it would be better. The question does have the keyword "decorate", so an answer with an actual "decorator" is fitting.

– Kimmo Lehto
Nov 22 '18 at 7:12

@KimmoLehto "actual" as in "as described by gang of four"? Their decorator implements the interface (maintains both api surface and type checks). Anyway, what I was trying to say is there are flavors of decorators. Who's to say which one of them is the "real" one? :)

– Sergio Tulentsev
Nov 22 '18 at 17:03

add a comment |

May be you want something as:

class ReaderDecorator

  def initialize(obj)

    @obj = obj

  end



  def read

    puts 'Hello'

    @obj.read

  end

end



ReaderDecorator.new(Book.new).read

ReaderDecorator.new(Magazine.new).read

answered Nov 21 '18 at 13:39

vk26

585

May be you want something as:

class ReaderDecorator

  def initialize(obj)

    @obj = obj

  end



  def read

    puts 'Hello'

    @obj.read

  end

end



ReaderDecorator.new(Book.new).read

ReaderDecorator.new(Magazine.new).read

answered Nov 21 '18 at 13:39

vk26

585

answered Nov 21 '18 at 13:39

vk26

585

answered Nov 21 '18 at 13:39

vk26

585

answered Nov 21 '18 at 13:39

vk26

585

I think this is the correct example of "decorator pattern".

– Kimmo Lehto
Nov 21 '18 at 13:49

1

@KimmoLehto: depends. For one thing, other methods are not proxied here (original object's API, if it were specified, is not reflected fully). And some clients may do type checks, so you might want your decorated object still be_a? the same type.

– Sergio Tulentsev
Nov 21 '18 at 13:55

@SergioTulentsev yes, with class ReaderDecorator < SimpleDelegator it would be better. The question does have the keyword "decorate", so an answer with an actual "decorator" is fitting.

– Kimmo Lehto
Nov 22 '18 at 7:12

@KimmoLehto "actual" as in "as described by gang of four"? Their decorator implements the interface (maintains both api surface and type checks). Anyway, what I was trying to say is there are flavors of decorators. Who's to say which one of them is the "real" one? :)

– Sergio Tulentsev
Nov 22 '18 at 17:03

add a comment |

I think this is the correct example of "decorator pattern".

– Kimmo Lehto
Nov 21 '18 at 13:49

1

@KimmoLehto: depends. For one thing, other methods are not proxied here (original object's API, if it were specified, is not reflected fully). And some clients may do type checks, so you might want your decorated object still be_a? the same type.

– Sergio Tulentsev
Nov 21 '18 at 13:55

@SergioTulentsev yes, with class ReaderDecorator < SimpleDelegator it would be better. The question does have the keyword "decorate", so an answer with an actual "decorator" is fitting.

– Kimmo Lehto
Nov 22 '18 at 7:12

@KimmoLehto "actual" as in "as described by gang of four"? Their decorator implements the interface (maintains both api surface and type checks). Anyway, what I was trying to say is there are flavors of decorators. Who's to say which one of them is the "real" one? :)

– Sergio Tulentsev
Nov 22 '18 at 17:03

I think this is the correct example of "decorator pattern".

– Kimmo Lehto
Nov 21 '18 at 13:49

@KimmoLehto: depends. For one thing, other methods are not proxied here (original object's API, if it were specified, is not reflected fully). And some clients may do type checks, so you might want your decorated object still be_a? the same type.

– Sergio Tulentsev
Nov 21 '18 at 13:55

@SergioTulentsev yes, with class ReaderDecorator < SimpleDelegator it would be better. The question does have the keyword "decorate", so an answer with an actual "decorator" is fitting.

– Kimmo Lehto
Nov 22 '18 at 7:12

@KimmoLehto "actual" as in "as described by gang of four"? Their decorator implements the interface (maintains both api surface and type checks). Anyway, what I was trying to say is there are flavors of decorators. Who's to say which one of them is the "real" one? :)

– Sergio Tulentsev
Nov 22 '18 at 17:03

add a comment |

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