In some legacy code i have see the following extension method to facilitate adding a new key-value item or updating the value, if the key already exists.
Method-1 (legacy code).
public static void CreateNewOrUpdateExisting<TKey, TValue>(
this IDictionary<TKey, TValue> map, TKey key, TValue value)
{
if (map.ContainsKey(key))
{
map[key] = value;
}
else
{
map.Add(key, value);
}
}
Though, I have checked that map[key]=value
does exactly the same job. That is, this method could be replace with Method-2 below.
Method-2.
public static void CreateNewOrUpdateExisting<TKey, TValue>(
this IDictionary<TKey, TValue> map, TKey key, TValue value)
{
map[key] = value;
}
Now, my question is.. Could there be any problem if i replace Method-1 by Method-2? Will it break in any possible scenario?
Also, I think this used to be the difference between HashTable and Dictionary. HashTable allows updating an item, or adding a new item by using indexer while Dictionary does not!! Is this difference been eliminated in C# > 3.0 versions?
The objective of this method is not too throw exception if user sends the same key-value again, the method should just update the entry with the new value, and to make a new entry if new key-value pair has been send to the method.
Best Answer
No, just use
map[key] = value
. The two options are equivalent.Regarding
Dictionary<>
vs.Hashtable
: When you start Reflector, you see that the indexer setters of both classes callthis.Insert(key, value, add: false);
and theadd
parameter is responsible for throwing an exception, when inserting a duplicate key. So the behavior is the same for both classes.