[FR] CommonPlot interface

[ocots]

It would be nice to have a CommonPlot.jl package as CommonSolve.jl where plot and plot! are defined (maybe others too). Then, the plot and plot! from Plots would have to extend those from CommonPlot.

It would be possible to define in any other ecosystem a plot function without ambiguity with Plots. Besides, it would make possible to have Plots.jl as an extension with plot extended twice, first in the main module to return a message like "please make: julia> using Plots" and secondly in the extension.

[BeastyBlacksmith]

We already have that in RecipesBase

Plots.jl/RecipesBase/src/RecipesBase.jl

Line 26 in 29a8007

function plot end

However, if you just want that to avoid naming conflicts, its not really an interface. If your plot function would want to adhere to the Plots.plot interface it would indeed need to be compatible with Plots recipes.

[ocots]

Thank you for your answer. Actually "interface" is not the right word. I just want to extend the plot function in order to plot a type from our package. I want Plots.jl to be part of the extensions but I want to tell to the user to make a "using Plots" if he tries to plot something from us and forget to do it.

I have added this to my code:

https://github.com/control-toolbox/CTModels.jl/blob/0c2c1c25611572bb8d9b89c4fa1dedbd1c8bec31/src/CTModels.jl#L34-L40

function RecipesBase.plot(sol::AbstractSolution; kwargs...)
    throw(CTBase.ExtensionError(:Plots))
end
function RecipesBase.plot!(p::RecipesBase.AbstractPlot, sol::AbstractSolution; kwargs...)
    throw(CTBase.ExtensionError(:Plots))
end

which is then extended in the extension when Plots is imported. At the end, to plot an optimal control solution (CTModels.Solution), I have:

function Plots.plot!(
    p::Plots.Plot,
    sol::CTModels.Solution;
    layout::Symbol=__plot_layout(),
    control::Symbol=__control_layout(),
    time::Symbol=__time_normalization(),
    solution_label::String="",
    state_style=(),
    control_style=(),
    costate_style=(),
    kwargs...,
)
...
end

function Plots.plot(
    sol::CTModels.Solution;
    layout::Symbol=__plot_layout(),
    control::Symbol=__control_layout(),
    time::Symbol=__time_normalization(),
    size=__size_plot(sol, control),
    solution_label::String="",
    state_style=(),
    control_style=(),
    costate_style=(),
    kwargs...,
)
...
end

[BeastyBlacksmith]

I'd say you should also define methods for RecipesBase.plot instead of Plots.plot in your extension.

Does this work for you? And if not what is the error?