At some point in the many years since I’ve been using R#, they have sneaked in a very useful feature, but hidden it so well that it took me until now to find it.

Say you have a horrible method like:

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Task UploadFileAsync(string fileName,
            IList<Resource> resources,
            ResourceCacheMethod cacheMethod,
            bool isThumbnail,
            IProgress<double> progress = null)

You put the cursor on/inside the method name, then press Ctrl-Shift-R (or whatever triggers Refactor this... for you), then select, on the very bottom of the context-menu, Transform parameters. In the dialog popping up you call the target class, for example, FileUpload, and, eh voila, the signature is transformed to

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Task UploadFileAsync(FileUpload fileUpload)

and a corresponding FileUpload type is created, and all calls are adjusted.

My only quibble with this is that it generates a constructor in FileUpload with all parameters, which typically is not what you want when you refactor legacy code and need this kinda thing. (Because when you want to introduce a parameter object, it’s usually because you have like 5 overloads of the method with different parameter combinations.) There should at least be an option to use initializer syntax instead.