Allow keeping value cache with formula cells
Created originally on Bitbucket by matthew_schwickerath (Matthew Schwickerath)
Having read other issues, I know that you are purposely throwing away the cached values for formula cells.
We currently have a home-grown way of generating XLSX, but it has many failings that openpyxl solves (this is a great library!). Our own solution is calculating the cache value manually so that if a user opens our spreadsheet via download (putting it into "protected" mode) it will still display the values. It also has the advantage that the user does not get prompted to save the spreadsheet when it is closed.
Would it be possible to support writing the workbook so that it can write a cache value for formula cells? Then our program using openpyxl could fill in the cache value for each formula cell and our end users could continue to get the advantages of cached values when they open our spreadsheets.