以" = "结尾的ruby方法是什么意思?

What does a ruby method ending with an "=" mean?

以"="结尾的ruby方法是什么意思?

See the available methods in this print out:

请参阅本手册中可用的方法:

 2.2.0 :066 > obj.methods(false)
 => [:label=, :label, :description=, :description, :thumbnail=, :thumbnail, :attribution=, :attribution, :license=, :license, :logo=, :logo, :see_also=, :seeAlso=, :see_also, :seeAlso, :related=, :related, :within=, :within, :metadata=, :metadata, :sequences=, :sequences, :structures=, :structures, :viewing_hint=, :viewingHint=, :viewing_hint, :viewingHint, :viewing_direction=, :viewingDirection=, :viewing_direction, :viewingDirection, :service=, :service]

For example whats this difference between label= and label?

例如，label=和label之间有什么区别?

4 个解决方案

#1

the methods ending with "=" are setting the instance variable

以“=”结尾的方法是设置实例变量。

look at the answer here: why-use-rubys-attr-accessor-attr-reader-and-attr-writer

看看这里的答案:why-use-rubys- attro -reader- reader- reader- reader- reader。

#2

foo= is no different than any other method, except:

foo=与其他方法没有区别，除了:

it requires precisely one argument and
它只需要一个论证
Ruby permits you to add spaces before the = character.
Ruby允许您在=字符之前添加空格。

class Foo
  def foo=(other)
    puts 'hi'
  end
end
Foo.new.foo                 = 7
hi

class Goo
  def goo=
    puts 'hi'
  end
end
Goo.new.goo=

Ruby says, "I'm waiting for an argument...". So we provide one:

Ruby说:“我在等一个争论……”所以我们提供:

and then she complains about what she asked you to do:

然后她抱怨她要你做的事:

#=> ArgumentError: wrong number of arguments (1 for 0)

= methods are typically used to create a setter for an instance variable (if attr_acccessor or attr_writer is not used):

=方法通常用于为实例变量创建setter(如果不使用attr_acccessor或attr_writer):

class Foo
  def initialize(foo)
    @foo=foo
  end
  # getter
  def foo
    @foo
  end
  # setter
  def foo=(other)
    @foo = other
  end
end

f = Foo.new('dog')
f.foo
  #=> "dog" 
f.foo = 'cat'
  #=> "cat" 
f.foo
  #=> "cat"

#3

It is equivalent of setter methods in other languages, it is just convention so it looks more natural to say

它相当于其他语言中的setter方法，它只是一种约定，所以它看起来更自然

obj.description="Fun Site"

obj.setDescription("Fun Site")

#4

There is nothing special about methods that end in =

以=结尾的方法没有什么特别之处

You can see this by running the code below:

你可以通过下面的代码看到这一点:

def bob=
   puts "bob="
end

p send('bob='.to_sym)

What is special is the '=' infix operator. When you write self.bob = "bill". It is interpreted as self.send('bob='.to_sym, "bill").

特殊的是'='中缀运算符。当你写自我。鲍勃=“比尔”。它被解释为self.send('bob=')。to_sym,“法案”)。

Putting a ? at the end of a method is a hint that it returns a boolean (true/false). Methods that end in ! hint that the method affects the instance. See String#chomp vs String#chomp.

把一个吗?在方法的末尾有一个提示，提示它返回一个布尔值(true/false)。方法结束!提示该方法影响实例。看到字符串# # chomp chomp vs字符串。

You can find out more about ruby operators at http://www.tutorialspoint.com/ruby/ruby_operators.htm and more about naming conventions at https://github.com/bbatsov/ruby-style-guide#naming

您可以在http://www.tutorialspoint.com/ruby/ruby_operators.htm上了解更多关于ruby操作符的信息，并在https://github.com/bbatsov/ruby-style-guide#命名中了解更多关于命名约定的信息

#1