Question

我正在尝试使用以下代码将条目（已从键盘读取）添加到Ruby哈希：

if schemes.has_key?(schemeName)
   puts "This scheme has already been added "
 else
   schemes.add(schemeName)
 end

'schemes'是我的哈希的名称，'schemeName'是我存储用户输入的数据的变量。但是，出于某种原因，我收到一条错误，说'add'是一个未定义的方法......我认为那是哈希数据类型的内置方法？

我班的完整代码是：

class CourseModules
# To change this template use File | Settings | File Templates.
@@moduleScheme = nil
@@moduleYear = nil
#@moduleTitle = ""
@noOfModulesInScheme = 0

def self.moduleYear
 @@moduleYear
end

def initialize(v)
 @val = v
end
# Set and get the @val object value
def set (v)
 @val = v
end
def get
 return @val
end

def addModule
 moduleName = Module.new(30)
 moduleRefNo = Random(100)
 #moduleTitle = @moduleTitle
 moduleYear(4)

 print "What is the name of the module you would like to add?"
 moduleName = gets
 moduleRefNo
 printf "Which year does the module belong to?"
 @@moduleYear = gets
 puts "#{moduleName}, belonging to #{@@moduleYear} has been added to the system, with reference number #{moduleRefNo}."
 navigateTo Application

end

def self.addModuleToScheme
=begin
Create an empty hash for the schemes
=end
 schemes = Hash.new()
=begin
Allow user to enter scheme names into a set of variables, and use each scheme name as a hash/ array of modules.
Then allow the user to enter the the modules for each scheme into each of the hashes

Create specific hash elements by using the following line:
schemes = {:scheme1 => scheme1variable, :scheme2 => scheme2variable}
=end

 puts "What is the name of the scheme that you would like to add a module to? "
 schemeName = gets
=begin
Need to use an if statement here to check whether or not the scheme already exists, if it doesn't, create it, if it does,
tell the user that it does.
=end
 if schemes.has_key?(schemeName)
   puts "This scheme has already been added "
 else
   schemes.add(schemeName)
 end

 noOfModulesInScheme + 1
 moduleName.moduleScheme = schemeName
end
def removeModuleFromScheme
 moduleName.moduleScheme = nil
end

def queryModule

end

end

有人能指出我为什么会收到未定义的方法错误吗？

Answer 1

哈希没有add方法（see here）。它确实有store，需要密钥和密钥。值对，所以你的代码可能是：

if schemes.has_key?(schemeName)
   puts "This scheme has already been added "
else
   schemes.store(schemeName, scheme)
end

Ruby未定义的哈希方法

1 个答案: