Adding dynamic redirects. Fix for #793

Fix for #793 

*Do not merge this yet!!!!*

This change removes all static binding redirects in app.config, and introduces dynamic redirects in core. The way this is done is by listening to the AssemblyResolve event on the AppDomain, and loading / returning the assembly to redirect to. It turns out using this technique you can swap on the fly and give a different assembly than what was requested.

At startup, it builds a map in map in memory based on the assemblies that scriptcs ships with ensuring that any requests for the same names will be redirected to it's version. It also ensures that any packages in the scriptcs packages folder take precedence over what the script pack / packages assemblies were actually compiled against.

Assembly black magic at its finest....

It appears to work so far :-)

This does not fix the Service Stack script pack issue, as there appears to be no magical fix for that other than updating the script pack. However, I was able to get the old Web Api script pack to work with the latest Web Api (see comments)


These methods should only be called before resolution had taken place.

To be safe we should probably freeze once resolve has fired. Otherwise if
we do what you suggest it might work or it might not and that is a brittle
system to depend on.

If we freeze we make it clear that you should seed the assemblies up front
before anything is resolved.

On Wednesday, July 23, 2014, Adam Ralph <notifications@github.com> wrote:

> In src/ScriptCs.Core/AppDomainAssemblyResolver.cs:
>
> > +
> > +        public void AddAssemblyPaths(IEnumerable<string> assemblyPaths)
> > +        {
> > +            foreach (var assemblyPath in assemblyPaths)
> > +            {
> > +                var info = new AssemblyInfo {Path = assemblyPath};
> > +                var name = AssemblyName.GetAssemblyName(assemblyPath);
> > +                info.Version = name.Version;
> > +
> > +                AssemblyInfo foundInfo = null;
> > +                var found = _assemblyInfoMap.TryGetValue(name.Name, out foundInfo );
> > +
> > +                if (!found || foundInfo.Version.CompareTo(info.Version) < 0)
> > +                {
> > +                    _logger.DebugFormat("Mapping Assembly {0} to version:{1}", name.Name, name.Version);
> > +                    _assemblyInfoMap[name.Name] = info;
>
> Something just struck me here. If this method has been called after some
> custom resolution has taken place, we have no choice but to stick with the
> currently resolved versions of assemblies, so I think this block should
> only execute if found.Assembly == null.
>
> —
> Reply to this email directly or view it on GitHub
> <https://github.com/scriptcs/scriptcs/pull/798/files#r15331033>.
>