ruby

Ruby 语言技能

错误处理约定

Weirich raise/fail 约定

首次抛出异常时使用 fail，仅在重新抛出时使用 raise：

def process(order)
  fail ArgumentError, "Order cannot be nil" if order.nil?

  begin
    gateway.charge(order)
  rescue PaymentError => e
    logger.error("Payment failed: #{e.message}")
    raise  # re-raise with raise
  end
end

自定义异常层次结构

将领域异常归入一个基类错误：

module MyApp
  class Error < StandardError; end
  class PaymentError < Error; end
  class InsufficientFundsError < PaymentError; end
end

# Rescue at any granularity:
rescue MyApp::InsufficientFundsError  # specific
rescue MyApp::PaymentError            # category
rescue MyApp::Error                   # all app errors

用于预期失败的结果对象

对于预期的失败路径，使用结果对象而非异常：

class Result
  attr_reader :value, :error
  def self.success(value) = new(value: value)
  def self.failure(error) = new(error: error)
  def initialize(value: nil, error: nil) = (@value, @error = value, error)
  def success? = error.nil?
  def failure? = !success?
end

由调用方提供回退处理

让调用方通过代码块定义错误处理方式：

def fetch_user(id, &fallback)
  User.find(id)
rescue ActiveRecord::RecordNotFound => e
  fallback ? fallback.call(e) : raise
end

user = fetch_user(999) { |_| User.new(name: "Guest") }

完整模式和重试策略请参阅 references/error_handling.md。

现代 Ruby（3.x+）

模式匹配

case response
in { status: 200, body: { users: [{ name: }, *] } }
  "First user: #{name}"
in { status: (400..), error: message }
  "Error: #{message}"
end

# Find pattern
case array
in [*, String => str, *]
  "Found string: #{str}"
end

# Pin operator
expected = 200
case response
in { status: ^expected, body: }
  process(body)
end

其他 3.x+ 特性

# Endless methods (3.0+)
def square(x) = x * x
def admin? = role == "admin"

# Numbered block parameters (2.7+)
[1, 2, 3].map { _1 * 2 }

# Data class - immutable value objects (3.2+)
Point = Data.define(:x, :y)
p = Point.new(x: 1, y: 2)
p.with(x: 3)  # => Point(x: 3, y: 2)

# Hash#except (3.0+)
params.except(:password, :admin)

# filter_map (2.7+) - select + map in one pass
users.filter_map { |u| u.email if u.active? }

# tally (2.7+)
%w[a b a c b a].tally  # => {"a"=>3, "b"=>2, "c"=>1}

有关 Ractor、fiber 调度器、RBS 类型和高级模式匹配，请参阅 references/modern_ruby.md。

快速提升性能

冻结字符串字面量

# frozen_string_literal: true
# Add to top of every file. Prevents mutation, reduces allocations.
# When you need mutable: String.new("hello") or +"hello"

高效枚举

# each_with_object for building results (avoids intermediate arrays)
totals = items.each_with_object(Hash.new(0)) do |item, hash|
  hash[item.category] += item.amount
end

# Lazy enumerables for large/infinite sequences
(1..Float::INFINITY).lazy.select(&:odd?).map { _1 ** 2 }.first(10)

使用记忆化时注意 nil/false

# Simple (only works if result is truthy)
def users = @users ||= User.all.to_a

# Safe (handles nil/false results)
def feature_enabled?
  return @feature_enabled if defined?(@feature_enabled)
  @feature_enabled = expensive_check
end

字符串构建

# Bad: O(n^2) with +=
result = ""; items.each { |i| result += i.to_s }

# Good: O(n) with <<
result = String.new; items.each { |i| result << i.to_s }

# Best: join
items.map(&:to_s).join

有关 YJIT、GC 调优、基准测试和性能分析工具，请参阅 references/performance.md。

推荐的 Ruby 惯用法

守卫子句

def process(value)
  return unless value
  return unless value.valid?
  # main logic here
end

字面量数组构造器

STATES = %w[draft published archived]      # word array
FIELDS = %i[name email created_at]         # symbol array

使用 Hash#fetch 获取必需的键

config.fetch(:api_key)                     # raises KeyError if missing
config.fetch(:timeout, 30)                 # default value
config.fetch(:handler) { build_handler }   # lazy default

安全导航

user&.profile&.avatar_url  # returns nil if any link is nil

谓词和 Bang 约定

• ? 后缀：返回布尔值（empty?、valid?、admin?）
• ! 后缀：危险版本——会修改接收者或在失败时引发异常（save!、sort!）
• 定义 Bang 方法时，始终提供一个非 Bang 替代方法

参考资料

• references/modern_ruby.md - 模式匹配、Ractor、fiber 调度器、RBS 类型
• references/error_handling.md - 异常层次结构、结果对象、重试模式
• references/performance.md - YJIT、GC 调优、基准测试、性能分析