Pluto.jl: namespace collision in bound variable name

[FelixBenning]

I just reopened a notebook I worked on a couple of days before and when playing with the sliders Pluto becomes unresponsive at some point. This is the stacktrace displayed in the terminal:

Opening http://localhost:1234/?secret=6JAaIgC5 in your default browser... ~ have fun!

Press Ctrl+C in this terminal to stop Pluto

      From worker 2:       Updating registry at `C:\Users\felix\.julia\registries\General`
      From worker 2:      Resolving package versions...
      From worker 2:    No Changes to `D:\Google Drive\CodingPlayground\ScalarConservation\scalarConservationLaws\Project.toml`
      From worker 2:    No Changes to `D:\Google Drive\CodingPlayground\ScalarConservation\scalarConservationLaws\Manifest.toml`
      From worker 2:      Resolving package versions...
      From worker 2:    No Changes to `D:\Google Drive\CodingPlayground\ScalarConservation\scalarConservationLaws\Project.toml`
      From worker 2:    No Changes to `D:\Google Drive\CodingPlayground\ScalarConservation\scalarConservationLaws\Manifest.toml`
On worker 2:
cannot assign a value to variable Polynomials.degree from module workspace44
top-level scope at none:1
eval at .\boot.jl:331
top-level scope at none:1
eval at .\boot.jl:331
#103 at D:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\Distributed\src\process_messages.jl:290
run_work_thunk at D:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\Distributed\src\process_messages.jl:79
run_work_thunk at D:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\Distributed\src\process_messages.jl:88
#96 at .\task.jl:356
Stacktrace:
 [1] sync_end(::Channel{Any}) at .\task.jl:314
 [2] macro expansion at .\task.jl:333 [inlined]
 [3] remotecall_eval(::Module, ::Array{Int64,1}, ::Expr) at D:\buildbot\worker\package_win64\build\usr\share\julia\stdlib\v1.5\Distributed\src\macros.jl:218
 [4] eval_in_workspace(::Tuple{Pluto.ServerSession,Pluto.Notebook}, ::Expr) at C:\Users\felix\.julia\packages\Pluto\2pyPe\src\evaluation\WorkspaceManager.jl:259
 [5] (::Pluto.var"#custom_deletion_hook#190"{Pluto.var"#custom_deletion_hook#188#191"{Symbol,Int64}})(::Tuple{Pluto.ServerSession,Pluto.Notebook}, ::Set{Symbol}, ::Set{Tuple{Base.UUID,Array{Symbol,1}}}, ::Set{Expr}; to_run::Array{Pluto.Cell,1}) at C:\Users\felix\.julia\packages\Pluto\2pyPe\src\webserver\Dynamic.jl:191
 [6] run_reactive!(::Pluto.ServerSession, ::Pluto.Notebook, ::Pluto.NotebookTopology, ::Pluto.NotebookTopology, ::Array{Pluto.Cell,1}; deletion_hook::Function) at C:\Users\felix\.julia\packages\Pluto\2pyPe\src\evaluation\Run.jl:65      
 [7] macro expansion at C:\Users\felix\.julia\packages\Pluto\2pyPe\src\evaluation\Run.jl:13 [inlined]
 [8] (::Pluto.var"#76#78"{Base.Iterators.Pairs{Symbol,Pluto.var"#custom_deletion_hook#190"{Pluto.var"#custom_deletion_hook#188#191"{Symbol,Int64}},Tuple{Symbol},NamedTuple{(:deletion_hook,),Tuple{Pluto.var"#custom_deletion_hook#190"{Pluto.var"#custom_deletion_hook#188#191"{Symbol,Int64}}}}},Pluto.ServerSession,Pluto.Notebook,Pluto.NotebookTopology,Pluto.NotebookTopology,Array{Pluto.Cell,1}})() at .\task.jl:356

At this point changing the sliders does not update graphs and manually reevaluating the cells which would display the graphs causes the loading animation to show but it does not stop.

you can find the notebook I am using here: https://github.com/FelixBenning/ScalarConservationLaws/blob/pluto_bug_report/src/homework_1.jl

[FelixBenning]

It appears that my definition of

@bind degree Slider(1:length(n_vector)-1, default=1, show_value=true)

caused a name collision with Polynomials.degree which in turn caused Pluto to crash. Renaming the variable to deg fixes my problems. Nevertheless Pluto should not crash when namespace collisions happen.

The lesson I am going to take from this, is that I should never have tried out Julias using import style and trusted my gut which said that it is a terrible idea to use the python equivalent of from module import * all the time.

[dralletje]

@FelixBenning yeah, Pluto has a pretty hard time with using ..., though it's the most used syntax in the Julia community ☹️
Obviously it should not crash, though, so good issue 👍

[fonsp]

(Although I agree with your gut feeling, using is different from from m import * in that you are only importing the globals that the package author explicitly exported, not its internals.)