Disable Cell button

[lungben]

My first works on #298

Still very WIP!

Use Cases:

• give a method to prevent auto-update of cells which take too long to compute to keep the notebook reactive and/or save computational resources.
• step-by-step computations for educational purposes

Suggestion:

• Allow the users to add execution barriers to Pluto cells from inside Pluto.
• These barriers block execution of the cell they are added to (i.e. located before the cell) if active.
• The barriers should be stored in the notebook.jl file, e.g. as comments.
• If the notebook.jl file is executed in Julia (without Pluto), the whole file should run, ignoring execution barriers (there would be no way to turn them off without Pluto anyhow).
• If an execution barrier is active, the cell and all cells depending on this cell should be marked gray in Pluto, so that it is obvious that they are not executed.
• When deactivating an execution barrier, the corresponding cell and all dependent cells are executed immediately and not grayed out anymore.

Technical implementation:

• Execution barrier information (is there a barrier? is it active?) could be added to the Cell structs in the backend.
• Save this information in notebook.jl files and load it from there
• Based on which cells are deactivated and the cell dependency information, the backend decides which cells to evaluate in case of changes.
• Pass the barrier information to the frontend
• In the frontend, the information whether a cell is grayed out is determined based on the execution barrier information in the Cells and the cell dependency information from Visualize cell dependencies (Backend) #891
• Frontend functionality for activating and deactivating of execution barriers plus visualization of execution barrirers required.
• Pass changes in barrier information back to the backend
• Run cell if its execution barrier is deactivated and it does not depend on any activated barrier
• Tests?
• Merge current master (currently not working for me out-of-the-box)

Note: this PR is based on #891, the first commit specific to this PR is 5975d25.

Try it out!

julia> ]
pkg> activate --temp
pkg> add https://github.com/lungben/Pluto.jl#execution_barrier
julia> import Pluto; Pluto.run()

[fonsp]

Looks good! Thanks again for your patience and for working together on getting this done!

Before we merge, I would like to:

• Tweak the CSS and JS
• Fix layout for touch input devices
• Try to break it :)
• Run button is broken/confusing for disabled cells
• On disabled cells, Shift+Enter should save code changes without enabling them
• set_waiting_to_run is buggy
• Stack overflow when clicking on a RunArea when a circular referencing cell is disabled
• Circular referencing cells do not show greyed out
• Clean up julia code

I will work on it right now!

[fonsp]

I reused the existing topological_order function to find the indirectly disabled cells: 47934ce (#985) This makes the PR much smaller :)

[lungben]

Cool, thanks!

[fonsp]

[oschulz]

Yay!!

[rajithv]

Does the temporary execution barrier work in 0.14.8? I'm trying to find how to use this feature. Thanks!

[lungben]

Yes. You can activate it by pressing the (...) button at the right side of the cell and then "Disable Cell".