How does HasManyThrough differ from MappedManyToMany?

Most of the lift-mapper documentation on many-to-many relationships documents the use of MappedManyToMany for mapping the relationship. But in 开发者_Python百科in Exploring Lift, I see that the authors use HasManyThrough instead.

What's the difference between the two? Is one preferred over the other?

HasManyThrough

• only gives you read support
• you will have to call get on it to get the elements
• you need to create the join table entries manually

MappedManyToMany

• also handles writes
• can be used like a collection (for example add and remove objects with += and -=)
• join table entries will be created automatically

At least these are the differences I noticed when moving from HasManyThrough to MappedManyToMany in my project.

So I think MappedManyToMany is a new version and is the preferred one, while HasManyThrough is propably kept for compatibility reasons.