Be careful – these aren’t the same thing.
- LoadFrom() goes through Fusion and can be redirected to another assembly at a different path but with that same identity if one is already loaded in the LoadFrom context.
- LoadFile() doesn’t bind through Fusion at all – the loader just goes ahead and loads exactly* what the caller requested. It doesn’t use either the Load or the LoadFrom context.
So, LoadFrom() usually gives you what you asked for, but not necessarily. LoadFile() is for those who really, really want exactly what is requested. (*However, starting in v2, policy will be applied to both LoadFrom() and LoadFile(), so LoadFile() won’t necessarily be exactly what was requested. Also, starting in v2, if an assembly with its identity is in the GAC, the GAC copy will be used instead. Use ReflectionOnlyLoadFrom() to load exactly what you want – but, note that assemblies loaded that way can’t be executed.)
LoadFile() has a catch. Since it doesn’t use a binding context, its dependencies aren’t automatically found in its directory. If they aren’t available in the Load context, you would have to subscribe to the AssemblyResolve event in order to bind to them.
So, which one should you use? That depends on which binding context is right for you and whether it matters that the LoadFrom context may redirect the bind. Regarding the latter:
- If no other code can load assemblies in your AppDomain, your LoadFrom() call can prevent a redirect* by just not loading anything else with a duplicate identity.
- If you do need to load a duplicate, you could get away with it by loading it into anything other than the LoadFrom context (or into another AppDomain) instead.
- But, maybe the redirect is really okay. Are they identical assemblies, just at different paths? If yes, it may be safe to risk the redirect unless its dependencies aren’t available in the dir of the first one loaded.
- Or, are they possibly different bits, just with the same assembly identity? If so, it may be unsafe to risk the redirect: maybe you’ll get an more-updated/not-as-updated version which you didn’t expect. Or, if it’s not strongly-named, maybe this is a third-party’s assembly, totally unrelated to the one you expect.