From the doc
从文档
Add(CacheItem, CacheItemPolicy) : When overridden in a derived class, tries to insert a cache entry into the cache as a CacheItem instance, and adds details about how the entry should be evicted. [1]
Add（CacheItem，CacheItemPolicy）：在派生类中重写时，尝试将缓存条目作为CacheItem实例插入缓存中，并添加有关如何逐出该条目的详细信息。 [1]
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Set(CacheItem, CacheItemPolicy) : When overridden in a derived class, inserts the cache entry into the cache as a CacheItem instance, specifying information about how the entry will be evicted. [2]
Set（CacheItem，CacheItemPolicy）：在派生类中重写时，将缓存条目作为CacheItem实例插入缓存中，指定有关如何逐出该条目的信息。 [2]
I see little difference in the wording (tries to) and signature (set is a sub, add returns a boolean), but I'm not sure which one I should use and if there is really something different between both.
我看到措辞（尝试）和签名（set是一个sub，add返回一个布尔值）没什么区别，但是我不确定我应该使用哪一个，以及两者之间是否真的有什么不同。
1 个解决方案
#1
26
The Main difference is that the Add() method tries to insert a cache without overwriting an existing cache entry with the same key.
主要区别在于Add（）方法尝试插入缓存而不覆盖具有相同密钥的现有缓存条目。
While the Set() method will overwrite an existing cache entry having the same key. [ However If the key for an item does not exist, insertion will be done as a new cache entry ].
而Set（）方法将覆盖具有相同密钥的现有缓存条目。 [但是，如果项目的密钥不存在，则插入将作为新的缓存条目完成]。
Above was the difference in terms of their functionality.
以上是其功能的差异。
Syntactical Difference:
句法差异：
One significant syntactical difference is that the Add() method returns a Boolean which is true if insertion succeeded, or false if there is already an entry in the cache that has the same key as item. The Set() method has a void return type.
一个重要的语法区别是Add（）方法返回一个布尔值，如果插入成功则返回true;如果缓存中已有一个与item具有相同键的条目，则返回false。 Set（）方法具有void返回类型。
One last point that internal implementation of Add() method actually calls its corresponding version of AddOrGetExisting() method.
最后一点，Add（）方法的内部实现实际上调用了相应版本的AddOrGetExisting（）方法。
public virtual bool Add(CacheItem item, CacheItemPolicy policy)
{
return this.AddOrGetExisting(item, policy) == null;
}
#1
26
The Main difference is that the Add() method tries to insert a cache without overwriting an existing cache entry with the same key.
主要区别在于Add（）方法尝试插入缓存而不覆盖具有相同密钥的现有缓存条目。
While the Set() method will overwrite an existing cache entry having the same key. [ However If the key for an item does not exist, insertion will be done as a new cache entry ].
而Set（）方法将覆盖具有相同密钥的现有缓存条目。 [但是，如果项目的密钥不存在，则插入将作为新的缓存条目完成]。
Above was the difference in terms of their functionality.
以上是其功能的差异。
Syntactical Difference:
句法差异：
One significant syntactical difference is that the Add() method returns a Boolean which is true if insertion succeeded, or false if there is already an entry in the cache that has the same key as item. The Set() method has a void return type.
一个重要的语法区别是Add（）方法返回一个布尔值，如果插入成功则返回true;如果缓存中已有一个与item具有相同键的条目，则返回false。 Set（）方法具有void返回类型。
One last point that internal implementation of Add() method actually calls its corresponding version of AddOrGetExisting() method.
最后一点，Add（）方法的内部实现实际上调用了相应版本的AddOrGetExisting（）方法。
public virtual bool Add(CacheItem item, CacheItemPolicy policy)
{
return this.AddOrGetExisting(item, policy) == null;
}