Ability to add local parameters

Sometimes I need to have parameter for a specific Look that shouldn’t really go to the view code. It could be something simple as manipulating the output of Yes/No column that’s then used for visualisation.

It would be a nice feature (something I got used to while using SSRS) to be able to create local parameter in the UI that then could be used in Custom Fields.

“Why won’t you use that field as a filter”, you might be asking. Well, the thing is that the filter will be applied in SQL, which I can’t have. I still want all the data to be shown for correct proportion (%) calculations. Only the result of the parameter could end up in SQL depending on where it’s used but it wouldn’t go to WHERE but rather into the CASEs

What do you guys think?