如何在Ruby中实现一个复杂的类查找功能？

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我有一份不可变值的对象列表。`lookup` 类提供了遍历和查询数据的方法：

rubyclass Banker class Bank

def initialize @banks=[ Bank.new('Citibank', '1234567', ['1', '2']) ] end endend

我有一个不可变值对象列表. lookup类提供了迭代和查询数据的方法：

class Banker Bank = Struct.new(:name, :bic, :codes) attr_reader :banks def initialize @banks = [ Bank.new('Citibank', '1234567', ['1', '2']), Bank.new('Wells Fargo', '7654321', ['4']), # etc. ] end def find_by_bic(bic) banks.each do |bank| return bank if bank.bic == bic end end end

每次使用银行家时都会初始化@banks.有哪些选项可以缓存@banks,以便它可以在Banker的不同实例中重复使用？

我不认为Struct在这里买了什么.这样做怎么样？

码

class Banker @all_banks = {} class << self attr_reader :all_banks end attr_reader :banks def initialize(banks) @banks = banks.keys banks.each { |k,v| self.class.all_banks[k] = v } end def find_by_bic(bic) return nil unless @banks.include?(bic) self.class.all_banks[bic] end end

注意self.class中的self是区分self类和关键字class所必需的.

例

b1 = Banker.new({ '1234567' => { name: 'Citibank', codes: ["1", "2"] }, '7654321' => { name: 'Wells Fargo', codes: ['4'] } }) b1.banks #=> ["1234567", "7654321"] Banker.all_banks #=> {"1234567"=>{:name=>"Citibank", :codes=>["1", "2"]}, # "7654321"=>{:name=>"Wells Fargo", :codes=>["4"]}} b1.find_by_bic '7654321' #=> {:name=>"Wells Fargo", :codes=>["4"]} b1.find_by_bic '1234567' #=> {:name=>"Citibank", :codes=>["1", "2"]} b1.find_by_bic '0000000' #=> nil b2 = Banker.new({ '6523155' => { name: 'Bank of America', codes: ["3"] }, '1234567' => { name: 'Citibank', codes: ["1", "2"] } }) b2.banks #=> ["6523155", "1234567"] Banker.all_banks #=> {"1234567"=>{:name=>"Citibank", :codes=>["1", "2"]}, # "7654321"=>{:name=>"Wells Fargo", :codes=>["4"]}, # "6523155"=>{:name=>"Bank of America", :codes=>["3"]}} b2.find_by_bic '6523155' #=> {:name=>"Bank of America", :codes=>["3"]} b2.find_by_bic '1234567' #=> {:name=>"Citibank", :codes=>["1", "2"]} b2.find_by_bic '7654321' #=> nil

备择方案

如果您愿意,可以改为添加类方法：

def self.new(banks) banks.each { |k,v| all_banks[k] = v } super end

并删除初始化中的第一行.

或者,如果你有一个完整的所有银行列表,你可以改为使all_banks成为常数：

ALL_BANKS = {"1234567"=>{:name=>"Citibank", :codes=>["1", "2"]}, "7654321"=>{:name=>"Wells Fargo", :codes=>["4"]}, "6523155"=>{:name=>"Bank of America", :codes=>["3"]}} def find_by_bic(bic) return nil unless @banks.include?(bic) ALL_BANKS[bic] end

并将initialize更改为：

def initialize(bics) @banks = bics end

其中bics是一组bic值.