需要将以下代码从 Ruby 转换为 C#。但是，我对 yield 关键字的使用和 Ruby 的一般语法感到有些困惑。任何知道一点Ruby的人都可以帮忙并转换代码

class < < Cache
STALE_REFRESH = 1
STALE_CREATED = 2

# Caches data received from a block
#
# The difference between this method and usual Cache.get
# is following: this method caches data and allows user
# to re-generate data when it is expired w/o running
# data generation code more than once so dog-pile effect
# won't bring our servers down
#
def smart_get(key, ttl = nil, generation_time = 30.seconds)
  # Fallback to default caching approach if no ttl given
  return get(key) { yield } unless ttl

  # Create window for data refresh
  real_ttl = ttl + generation_time * 2
  stale_key = "#{key}.stale"

  # Try to get data from memcache
  value = get(key)
  stale = get(stale_key)

  # If stale key has expired, it is time to re-generate our data
  unless stale
    put(stale_key, STALE_REFRESH, generation_time) # lock
    value = nil # force data re-generation
  end

  # If no data retrieved or data re-generation forced, re-generate data and reset stale key
  unless value
    value = yield
    put(key, value, real_ttl)
    put(stale_key, STALE_CREATED, ttl) # unlock
  end

  return value
end

最佳答案

我根本不懂 C#，所以我对 C# 说的任何话都应该持保留态度。但是，我将尝试解释这段 Ruby 代码中发生的事情。

class << Cache

  STALE_REFRESH = 1
  STALE_CREATED = 2

  # Caches data received from a block
  #
  # The difference between this method and usual Cache.get
  # is following: this method caches data and allows user
  # to re-generate data when it is expired w/o running
  # data generation code more than once so dog-pile effect
  # won't bring our servers down
  #
  def smart_get(key, ttl = nil, generation_time = 30.seconds)

    # Fallback to default caching approach if no ttl given
    return get(key) { yield } unless ttl

    # Create window for data refresh
    real_ttl = ttl + generation_time * 2
    stale_key = "#{key}.stale"

    # Try to get data from memcache
    value = get(key)
    stale = get(stale_key)

    # If stale key has expired, it is time to re-generate our data
    unless stale
      put(stale_key, STALE_REFRESH, generation_time) # lock
      value = nil # force data re-generation
    end

    # If no data retrieved or data re-generation forced, re-generate data and reset stale key
    unless value
      value = yield
      put(key, value, real_ttl)
      put(stale_key, STALE_CREATED, ttl) # unlock
    end

    return value
  end
end

public class Cache<Tkey, Tvalue> {
    enum Stale { Refresh, Created }

    /* Caches data received from a delegate
     *
     * The difference between this method and usual Cache.get
     * is following: this method caches data and allows user
     * to re-generate data when it is expired w/o running
     * data generation code more than once so dog-pile effect
     * won't bring our servers down
    */
    public static Tvalue SmartGet(Tkey key, TimeSpan ttl, TimeSpan generationTime, Func<Tvalue> strategy)
    {
        // Create window for data refresh
        var realTtl = ttl + generationTime * 2;
        var staleKey = String.Format("{0}stale", key);

        // Try to get data from memcache
        var value = Get(key);
        var stale = Get(staleKey);

        // If stale key has expired, it is time to re-generate our data
        if (stale == null)
        {
            Put(staleKey, Stale.Refresh, generationTime); // lock
            value = null; // force data re-generation
        }

        // If no data retrieved or data re-generation forced, re-generate data and reset stale key
        if (value == null)
        {
            value = strategy();
            Put(key, value, realTtl);
            Put(staleKey, Stale.Created, ttl) // unlock
        }

        return value;
    }

    // Fallback to default caching approach if no ttl given
    public static Tvalue SmartGet(Tkey key, Func<Tvalue> strategy) => 
        Get(key, strategy);

    // Simulate default argument for generationTime
    // C# 4.0 has default arguments, so this wouldn't be needed.
    public static Tvalue SmartGet(Tkey key, TimeSpan ttl, Func<Tvalue> strategy) => 
        SmartGet(key, ttl, new TimeSpan(0, 0, 30), strategy);

    // Convenience overloads to allow calling it the same way as 
    // in Ruby, by just passing in the timespans as integers in 
    // seconds.
    public static Tvalue SmartGet(Tkey key, int ttl, int generationTime, Func<Tvalue> strategy) => 
        SmartGet(key, new TimeSpan(0, 0, ttl), new TimeSpan(0, 0, generationTime), strategy);

    public static Tvalue SmartGet(Tkey key, int ttl, Func<Tvalue> strategy) => 
        SmartGet(key, new TimeSpan(0, 0, ttl), strategy);
}

关于c# - 将 Ruby 转换为 C#，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/744620/