Ruby alias alias_method confusion
I have this piece of code here:
class MyFile
attr_accessor :byte_content
alias_method :read, :byte_content
alias_method :write, :byte_content=
end
On the class MyFile there is an alias_method, but I do not understand how this method is working. Does it change the way the getter and setter for :byte_content are called?
Also, what is the difference between this method and just using alias? When should I one over the other?
Thanks in advance for your time!
ruby
edited Jan 2 at 12:47
Kimmo Lehto
4,20311329
asked Jan 2 at 12:20
Luiz MeloLuiz Melo
2216
add a comment |
I have this piece of code here:
class MyFile
attr_accessor :byte_content
alias_method :read, :byte_content
alias_method :write, :byte_content=
end
On the class MyFile there is an alias_method, but I do not understand how this method is working. Does it change the way the getter and setter for :byte_content are called?
Also, what is the difference between this method and just using alias? When should I one over the other?
Thanks in advance for your time!
ruby
edited Jan 2 at 12:47
Kimmo Lehto
4,20311329
asked Jan 2 at 12:20
Luiz MeloLuiz Melo
2216
2
It would be helpful, if you could explain precisely what is unclear to you about the documentation ofModule#alias_method. That way, the Ruby developers can improve the documentation so that future developers don't have the same problems you have. Also, it saves time and effort for people answering your question, so that they don't repeat things you already know, or repeat explanations that you don't understand. And lastly, it would help if you can check that your Minimal, Complete, and Verifiable example really is minimal. Are you absolutely certain that your problem cannot possibly be replicated in less than 25 lines?
– Jörg W Mittag
Jan 2 at 12:32
Thank you for your input, I will certainly keep this in mind in the future. I got confused about when to use one or the other regarding lexical scope, which I did not see in the documentation (there is only one example and it is not clear at all). I found this blog post about the topic and found it to be really helpful : blog.bigbinary.com/2012/01/08/alias-vs-alias-method.html My intention is to help other beginners (like myself) that face the same doubt in the future.
– Luiz Melo
Jan 2 at 13:17
Google "Ruby alais vs. alais method" and you will get plenty of hits that will tell you all you need to know about that, and much more.
– Cary Swoveland
Jan 2 at 20:52
add a comment |
I have this piece of code here:
class MyFile
attr_accessor :byte_content
alias_method :read, :byte_content
alias_method :write, :byte_content=
end
On the class MyFile there is an alias_method, but I do not understand how this method is working. Does it change the way the getter and setter for :byte_content are called?
Also, what is the difference between this method and just using alias? When should I one over the other?
Thanks in advance for your time!
ruby
edited Jan 2 at 12:47
Kimmo Lehto
4,20311329
asked Jan 2 at 12:20
Luiz MeloLuiz Melo
2216
I have this piece of code here:
class MyFile
attr_accessor :byte_content
alias_method :read, :byte_content
alias_method :write, :byte_content=
end
On the class MyFile there is an alias_method, but I do not understand how this method is working. Does it change the way the getter and setter for :byte_content are called?
Also, what is the difference between this method and just using alias? When should I one over the other?
Thanks in advance for your time!
ruby
ruby
edited Jan 2 at 12:47
Kimmo Lehto
4,20311329
asked Jan 2 at 12:20
Luiz MeloLuiz Melo
2216
edited Jan 2 at 12:47
Kimmo Lehto
4,20311329
asked Jan 2 at 12:20
Luiz MeloLuiz Melo
2216
edited Jan 2 at 12:47
Kimmo Lehto
4,20311329
edited Jan 2 at 12:47
Kimmo Lehto
4,20311329
edited Jan 2 at 12:47
Kimmo Lehto
4,20311329
4,20311329
asked Jan 2 at 12:20
Luiz MeloLuiz Melo
2216
asked Jan 2 at 12:20
Luiz MeloLuiz Melo
2216
asked Jan 2 at 12:20
Luiz MeloLuiz Melo
2216
2216
2
It would be helpful, if you could explain precisely what is unclear to you about the documentation ofModule#alias_method. That way, the Ruby developers can improve the documentation so that future developers don't have the same problems you have. Also, it saves time and effort for people answering your question, so that they don't repeat things you already know, or repeat explanations that you don't understand. And lastly, it would help if you can check that your Minimal, Complete, and Verifiable example really is minimal. Are you absolutely certain that your problem cannot possibly be replicated in less than 25 lines?
– Jörg W Mittag
Jan 2 at 12:32
Thank you for your input, I will certainly keep this in mind in the future. I got confused about when to use one or the other regarding lexical scope, which I did not see in the documentation (there is only one example and it is not clear at all). I found this blog post about the topic and found it to be really helpful : blog.bigbinary.com/2012/01/08/alias-vs-alias-method.html My intention is to help other beginners (like myself) that face the same doubt in the future.
– Luiz Melo
Jan 2 at 13:17
Google "Ruby alais vs. alais method" and you will get plenty of hits that will tell you all you need to know about that, and much more.
– Cary Swoveland
Jan 2 at 20:52
add a comment |
2
It would be helpful, if you could explain precisely what is unclear to you about the documentation ofModule#alias_method. That way, the Ruby developers can improve the documentation so that future developers don't have the same problems you have. Also, it saves time and effort for people answering your question, so that they don't repeat things you already know, or repeat explanations that you don't understand. And lastly, it would help if you can check that your Minimal, Complete, and Verifiable example really is minimal. Are you absolutely certain that your problem cannot possibly be replicated in less than 25 lines?
– Jörg W Mittag
Jan 2 at 12:32
Thank you for your input, I will certainly keep this in mind in the future. I got confused about when to use one or the other regarding lexical scope, which I did not see in the documentation (there is only one example and it is not clear at all). I found this blog post about the topic and found it to be really helpful : blog.bigbinary.com/2012/01/08/alias-vs-alias-method.html My intention is to help other beginners (like myself) that face the same doubt in the future.
– Luiz Melo
Jan 2 at 13:17
Google "Ruby alais vs. alais method" and you will get plenty of hits that will tell you all you need to know about that, and much more.
– Cary Swoveland
Jan 2 at 20:52
2
2
It would be helpful, if you could explain precisely what is unclear to you about the documentation of
Module#alias_method. That way, the Ruby developers can improve the documentation so that future developers don't have the same problems you have. Also, it saves time and effort for people answering your question, so that they don't repeat things you already know, or repeat explanations that you don't understand. And lastly, it would help if you can check that your Minimal, Complete, and Verifiable example really is minimal. Are you absolutely certain that your problem cannot possibly be replicated in less than 25 lines?– Jörg W Mittag
Jan 2 at 12:32
It would be helpful, if you could explain precisely what is unclear to you about the documentation of
Module#alias_method. That way, the Ruby developers can improve the documentation so that future developers don't have the same problems you have. Also, it saves time and effort for people answering your question, so that they don't repeat things you already know, or repeat explanations that you don't understand. And lastly, it would help if you can check that your Minimal, Complete, and Verifiable example really is minimal. Are you absolutely certain that your problem cannot possibly be replicated in less than 25 lines?– Jörg W Mittag
Jan 2 at 12:32
Thank you for your input, I will certainly keep this in mind in the future. I got confused about when to use one or the other regarding lexical scope, which I did not see in the documentation (there is only one example and it is not clear at all). I found this blog post about the topic and found it to be really helpful : blog.bigbinary.com/2012/01/08/alias-vs-alias-method.html My intention is to help other beginners (like myself) that face the same doubt in the future.
– Luiz Melo
Jan 2 at 13:17
Thank you for your input, I will certainly keep this in mind in the future. I got confused about when to use one or the other regarding lexical scope, which I did not see in the documentation (there is only one example and it is not clear at all). I found this blog post about the topic and found it to be really helpful : blog.bigbinary.com/2012/01/08/alias-vs-alias-method.html My intention is to help other beginners (like myself) that face the same doubt in the future.
– Luiz Melo
Jan 2 at 13:17
Google "Ruby alais vs. alais method" and you will get plenty of hits that will tell you all you need to know about that, and much more.
– Cary Swoveland
Jan 2 at 20:52
Google "Ruby alais vs. alais method" and you will get plenty of hits that will tell you all you need to know about that, and much more.
– Cary Swoveland
Jan 2 at 20:52
add a comment |
1 Answer
1
active
oldest
votes
This:
attr_accessor :byte_content
Essentially does:
def byte_content
@byte_content
end
def byte_content=(value)
@byte_content = value
end
Then
alias_method :read, :byte_content
alias_method :write, :byte_content=
will create copies of the byte_content and byte_content= methods with read and write as the new names . If you modify the byte_content or byte_content= methods after the aliasing, the read and write will remain unchanged.
So, the intention of the alias_method in the example appears to be to give the user a more "File-like" interface. Without the method aliases, you would use:
file = MyFile.new
file.byte_content = "abcd"
puts file.byte_content
With the aliases, the user can use:
file = MyFile.new
file.write("abcd")
file.read
Which is quite similar to the methods of the standard library File class,
file = File.open('/tmp/foo.txt', 'w')
file.write('hello')
file.rewind
puts file.read
And this makes it possible to use instances of MyFile in place of real File instances in some very simple use-cases, also known as Duck-typing.
alias vs alias_method
The differences of alias and alias_method are described in the answers to this question, most imporantly:
- you can override
alias_methodbut notalias
alias_methodis used with symbols as the method names, making it useful for dynamically created methods
answered Jan 2 at 12:39
Kimmo LehtoKimmo Lehto
4,20311329
The reason that alias_method can be overwritten is because it creates a copy of the method. In your example ofalias_method :read, :byte_contentthe content of the read method should be@byte_content.
– vise
Jan 2 at 13:03
1
@vise Updated the answer to mention the copying.
– Kimmo Lehto
Jan 2 at 13:10
That was extremely helpful. Thank you!
– Luiz Melo
Jan 2 at 13:20
add a comment |
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1 Answer
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oldest
votes
This:
attr_accessor :byte_content
Essentially does:
def byte_content
@byte_content
end
def byte_content=(value)
@byte_content = value
end
Then
alias_method :read, :byte_content
alias_method :write, :byte_content=
will create copies of the byte_content and byte_content= methods with read and write as the new names . If you modify the byte_content or byte_content= methods after the aliasing, the read and write will remain unchanged.
So, the intention of the alias_method in the example appears to be to give the user a more "File-like" interface. Without the method aliases, you would use:
file = MyFile.new
file.byte_content = "abcd"
puts file.byte_content
With the aliases, the user can use:
file = MyFile.new
file.write("abcd")
file.read
Which is quite similar to the methods of the standard library File class,
file = File.open('/tmp/foo.txt', 'w')
file.write('hello')
file.rewind
puts file.read
And this makes it possible to use instances of MyFile in place of real File instances in some very simple use-cases, also known as Duck-typing.
alias vs alias_method
The differences of alias and alias_method are described in the answers to this question, most imporantly:
- you can override
alias_methodbut notalias
alias_methodis used with symbols as the method names, making it useful for dynamically created methods
answered Jan 2 at 12:39
Kimmo LehtoKimmo Lehto
4,20311329
The reason that alias_method can be overwritten is because it creates a copy of the method. In your example ofalias_method :read, :byte_contentthe content of the read method should be@byte_content.
– vise
Jan 2 at 13:03
1
@vise Updated the answer to mention the copying.
– Kimmo Lehto
Jan 2 at 13:10
That was extremely helpful. Thank you!
– Luiz Melo
Jan 2 at 13:20
add a comment |
This:
attr_accessor :byte_content
Essentially does:
def byte_content
@byte_content
end
def byte_content=(value)
@byte_content = value
end
Then
alias_method :read, :byte_content
alias_method :write, :byte_content=
will create copies of the byte_content and byte_content= methods with read and write as the new names . If you modify the byte_content or byte_content= methods after the aliasing, the read and write will remain unchanged.
So, the intention of the alias_method in the example appears to be to give the user a more "File-like" interface. Without the method aliases, you would use:
file = MyFile.new
file.byte_content = "abcd"
puts file.byte_content
With the aliases, the user can use:
file = MyFile.new
file.write("abcd")
file.read
Which is quite similar to the methods of the standard library File class,
file = File.open('/tmp/foo.txt', 'w')
file.write('hello')
file.rewind
puts file.read
And this makes it possible to use instances of MyFile in place of real File instances in some very simple use-cases, also known as Duck-typing.
alias vs alias_method
The differences of alias and alias_method are described in the answers to this question, most imporantly:
- you can override
alias_methodbut notalias
alias_methodis used with symbols as the method names, making it useful for dynamically created methods
answered Jan 2 at 12:39
Kimmo LehtoKimmo Lehto
4,20311329
The reason that alias_method can be overwritten is because it creates a copy of the method. In your example ofalias_method :read, :byte_contentthe content of the read method should be@byte_content.
– vise
Jan 2 at 13:03
1
@vise Updated the answer to mention the copying.
– Kimmo Lehto
Jan 2 at 13:10
That was extremely helpful. Thank you!
– Luiz Melo
Jan 2 at 13:20
add a comment |
This:
attr_accessor :byte_content
Essentially does:
def byte_content
@byte_content
end
def byte_content=(value)
@byte_content = value
end
Then
alias_method :read, :byte_content
alias_method :write, :byte_content=
will create copies of the byte_content and byte_content= methods with read and write as the new names . If you modify the byte_content or byte_content= methods after the aliasing, the read and write will remain unchanged.
So, the intention of the alias_method in the example appears to be to give the user a more "File-like" interface. Without the method aliases, you would use:
file = MyFile.new
file.byte_content = "abcd"
puts file.byte_content
With the aliases, the user can use:
file = MyFile.new
file.write("abcd")
file.read
Which is quite similar to the methods of the standard library File class,
file = File.open('/tmp/foo.txt', 'w')
file.write('hello')
file.rewind
puts file.read
And this makes it possible to use instances of MyFile in place of real File instances in some very simple use-cases, also known as Duck-typing.
alias vs alias_method
The differences of alias and alias_method are described in the answers to this question, most imporantly:
- you can override
alias_methodbut notalias
alias_methodis used with symbols as the method names, making it useful for dynamically created methods
answered Jan 2 at 12:39
Kimmo LehtoKimmo Lehto
4,20311329
This:
attr_accessor :byte_content
Essentially does:
def byte_content
@byte_content
end
def byte_content=(value)
@byte_content = value
end
Then
alias_method :read, :byte_content
alias_method :write, :byte_content=
will create copies of the byte_content and byte_content= methods with read and write as the new names . If you modify the byte_content or byte_content= methods after the aliasing, the read and write will remain unchanged.
So, the intention of the alias_method in the example appears to be to give the user a more "File-like" interface. Without the method aliases, you would use:
file = MyFile.new
file.byte_content = "abcd"
puts file.byte_content
With the aliases, the user can use:
file = MyFile.new
file.write("abcd")
file.read
Which is quite similar to the methods of the standard library File class,
file = File.open('/tmp/foo.txt', 'w')
file.write('hello')
file.rewind
puts file.read
And this makes it possible to use instances of MyFile in place of real File instances in some very simple use-cases, also known as Duck-typing.
alias vs alias_method
The differences of alias and alias_method are described in the answers to this question, most imporantly:
- you can override
alias_methodbut notalias
alias_methodis used with symbols as the method names, making it useful for dynamically created methods
answered Jan 2 at 12:39
Kimmo LehtoKimmo Lehto
4,20311329
edited Jan 2 at 13:23
answered Jan 2 at 12:39
Kimmo LehtoKimmo Lehto
4,20311329
answered Jan 2 at 12:39
Kimmo LehtoKimmo Lehto
4,20311329
answered Jan 2 at 12:39
Kimmo LehtoKimmo Lehto
4,20311329
4,20311329
The reason that alias_method can be overwritten is because it creates a copy of the method. In your example ofalias_method :read, :byte_contentthe content of the read method should be@byte_content.
– vise
Jan 2 at 13:03
1
@vise Updated the answer to mention the copying.
– Kimmo Lehto
Jan 2 at 13:10
That was extremely helpful. Thank you!
– Luiz Melo
Jan 2 at 13:20
add a comment |
The reason that alias_method can be overwritten is because it creates a copy of the method. In your example ofalias_method :read, :byte_contentthe content of the read method should be@byte_content.
– vise
Jan 2 at 13:03
1
@vise Updated the answer to mention the copying.
– Kimmo Lehto
Jan 2 at 13:10
That was extremely helpful. Thank you!
– Luiz Melo
Jan 2 at 13:20
The reason that alias_method can be overwritten is because it creates a copy of the method. In your example of
alias_method :read, :byte_content the content of the read method should be @byte_content.– vise
Jan 2 at 13:03
The reason that alias_method can be overwritten is because it creates a copy of the method. In your example of
alias_method :read, :byte_content the content of the read method should be @byte_content.– vise
Jan 2 at 13:03
1
1
@vise Updated the answer to mention the copying.
– Kimmo Lehto
Jan 2 at 13:10
@vise Updated the answer to mention the copying.
– Kimmo Lehto
Jan 2 at 13:10
That was extremely helpful. Thank you!
– Luiz Melo
Jan 2 at 13:20
That was extremely helpful. Thank you!
– Luiz Melo
Jan 2 at 13:20
add a comment |
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2
It would be helpful, if you could explain precisely what is unclear to you about the documentation of
Module#alias_method. That way, the Ruby developers can improve the documentation so that future developers don't have the same problems you have. Also, it saves time and effort for people answering your question, so that they don't repeat things you already know, or repeat explanations that you don't understand. And lastly, it would help if you can check that your Minimal, Complete, and Verifiable example really is minimal. Are you absolutely certain that your problem cannot possibly be replicated in less than 25 lines?– Jörg W Mittag
Jan 2 at 12:32
Thank you for your input, I will certainly keep this in mind in the future. I got confused about when to use one or the other regarding lexical scope, which I did not see in the documentation (there is only one example and it is not clear at all). I found this blog post about the topic and found it to be really helpful : blog.bigbinary.com/2012/01/08/alias-vs-alias-method.html My intention is to help other beginners (like myself) that face the same doubt in the future.
– Luiz Melo
Jan 2 at 13:17
Google "Ruby alais vs. alais method" and you will get plenty of hits that will tell you all you need to know about that, and much more.
– Cary Swoveland
Jan 2 at 20:52