# Dispatch with @userplot and external recipes

**URL:** <https://discourse.julialang.org/t/dispatch-with-userplot-and-external-recipes/54045>\
**Category:** Visualization\
**Tags:** plots, recipe\
**Created:** [January 27, 2021, 10:38am UTC](https://discourse.julialang.org/t/dispatch-with-userplot-and-external-recipes/54045 "2021-01-27T10:38:19Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Libbum](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/libbum/32/3935_2.png) [@Libbum](https://discourse.julialang.org/u/Libbum)\
**Post date:** [January 27, 2021, 10:38am UTC](https://discourse.julialang.org/t/dispatch-with-userplot-and-external-recipes/54045/1 "2021-01-27T10:38:19Z")

</div>

Hi all,  
I’m trying to learn the [Plots.jl recipe syntax](http://docs.juliaplots.org/latest/recipes/) and have a few design questions.

Say I have

```julia
struct MyData{T} where {T<:Union{One,Two}}
   ...
end

```

I’d like to define `@userplot PlotCustom` for this, and provide two different plot types depending on the types `One` and `Two`.

```julia
julia> typeof(data)
MyData{One}
julia> plotcustom(data) # Produce a scatter plot
julia> typeof(data)
MyData{Two}
julia> plotcustom(data) # Produce a graphplot

```

**Question 1:** can/should I try to dispatch my recipe to two different methods, or is it fine to just put some if statement in the recipe and return different plots?  
For example:

```julia
data = h.args[1]
if data.plot_type isa One
    seriestype := :scatter
    ...
else
    seriestype := :graphplot
    ...
end

```

The issue I have with this is that I’d like to provide some defaults with the methods and they need to be different. So multiple dispatch would be better here, but I’m not sure how to correctly return the applied properties (e.g. `x := data.x`) from such a function call.

**Question 2.** How can I pass my properties to another recipe? My `Two` type here needs to be plotted via [graphplot](https://github.com/JuliaPlots/GraphRecipes.jl), so I cannot just provide `seriestype := :graphplot`,

---

<div class="post-metadata">

**Author:** ![Libbum](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/libbum/32/3935_2.png) [@Libbum](https://discourse.julialang.org/u/Libbum)\
**Post date:** [January 27, 2021, 7:54pm UTC](https://discourse.julialang.org/t/dispatch-with-userplot-and-external-recipes/54045/2 "2021-01-27T19:54:24Z")

</div>

OK, so I’ve solved this myself I think.

Part 1: rather than use `@userplot` I just made the functions that would have been generated by the macro manually, but made them dispatchable:

```julia
mutable struct PlotCustom{AbstractType}
    args::Any                                      
end
    
plotcustom(args...; kw...) = RecipesBase.plot(PlotCustom{typeof(args[1].count)}(args); kw...)
#etc

```

Part 2: So long as I’m `using GraphRecipes`, I can omit assigning a value to `seriestype`, and leave the last line of my recipe as an `<: AbstractGraph`. Then [the graph recipe](https://github.com/JuliaPlots/GraphRecipes.jl/blob/7346f8e7fa18a33a9848be19865bf468eaa2404d/src/graphs.jl#L947) will take over from there.

If anyone has a cleaner way of doing this I’d be interested to know!