How to manage Boot-time state for Snippets?

[James Earl Douglas]

I have a Snippet class that has an external dependency (e.g. a REST client for some third-party service).  Typically, I would inject this via a constructor argument, but since Lift uses reflection to instantiate Snippet classes on request, I'm not sure how best to do this.

1. I want the dependency externalized, so I can instantiate my Snippet class in a test and inject my own mock/stub version for testing.

2. I don't think I can use a constructor argument, since Lift won't be able to instantiate my Snippet class at request time.

Would it be better to have a global object (e.g. `object bootstrap.liftweb.Boot`) with a mutable variable that gets set by the Lift `Boot.boot` procedure?  A major downside to this is that the variable becomes an invisible dependency that I have to remember to set before running my test.

Is there any way for Lift to support a Snippet that has a constructor?  Or are there any better patterns for this?

[David Pollak]

James,

I tend to put this kind of thing in a SessionVar for stuff that's the duration of a session: https://liftweb.net/api/32/api/net/liftweb/http/SessionVar.html

Also, Lift supports Dependency Injection: https://app.assembla.com/wiki/show/liftweb/Dependency_Injection

Note the above Assembla article references Lift 2.x... there may be API changes in Lift 3.x

Hope this helps.

Thanks,

David

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