precompile functions to reduce compilation time of first plot

deps/generateprecompiles.jl

@@ -0,0 +1,27 @@
+# To figure out what should be precompiled, run this script, then move
+# precompile_Plots.jl in precompiles_path (see below) to src/precompile.jl
+
+using SnoopCompile
+
+log_path = joinpath(tempdir(), "compiles.log")
+precompiles_path = joinpath(tempdir(), "precompile")
+
+# run examples with GR backend, logging what needs to be compiled
+SnoopCompile.@snoopc log_path begin
+    using Plots
+    Plots.test_examples(:gr, disp=true)
+end
+
+# precompile calls containing the following strings are dropped
+blacklist = [
+    # functions defined in examples
+    "PlotExampleModule",
+    # the following are not visible to Plots, only its dependencies
+    "CategoricalArrays",
+    "FixedPointNumbers",
+    "SparseArrays"
+]
+
+data = SnoopCompile.read(log_path)
+pc = SnoopCompile.parcel(reverse!(data[2]), blacklist=blacklist)
+SnoopCompile.write(precompiles_path, pc)

src/Plots.jl

@@ -222,4 +222,7 @@ end
 
 const CURRENT_BACKEND = CurrentBackend(:none)
 
+include("precompile.jl")
+_precompile_()
+
 end # module

src/examples.jl

@@ -305,7 +305,8 @@ PlotExample("3D",
 
 PlotExample("DataFrames",
     "Plot using DataFrame column symbols.",
-    [:(begin
+    [:(using StatsPlots), # can't be inside begin block because @df gets expanded first
+     :(begin
         import RDatasets
         iris = RDatasets.dataset("datasets", "iris")
         @df iris scatter(:SepalLength, :SepalWidth, group=:Species,
@@ -354,7 +355,8 @@ PlotExample("Layouts, margins, label rotation, title location",
 
 PlotExample("Boxplot and Violin series recipes",
     "",
-    [:(begin
+    [:(using StatsPlots), # can't be inside begin block because @df gets expanded first
+     :(begin
         import RDatasets
         singers = RDatasets.dataset("lattice", "singer")
         @df singers violin(:VoicePart, :Height, line = 0, fill = (0.2, :blue))
@@ -518,7 +520,12 @@ function test_examples(pkgname::Symbol, idx::Int; debug = false, disp = true)
   @info("Testing plot: $pkgname:$idx:$(_examples[idx].header)")
   backend(pkgname)
   backend()
-  map(eval, _examples[idx].exprs)
+
+  # prevent leaking variables (esp. functions) directly into Plots namespace
+  m = Module(:PlotExampleModule)
+  Base.eval(m, :(using Plots))
+  map(exprs -> Base.eval(m, exprs), _examples[idx].exprs)
+
   plt = current()
   if disp
     gui(plt)