Optional dependencies / Requires.jl

Internals & Design
9

I haven’t looked at Plots in detail, but most of the time Julia’s late binding means that you can write a bulk of the heavy lifting code without the library you’re using being loaded. The main exception is adding new methods, for which you obviously need the function and any types to be available. But then you can use requires just for that one definition that ties together the two packages, i.e.

function real_foo(x)
  Foo.bar(x)
end

@require Foo begin
  using Foo
  Foo.foo(x::MyType) = real_foo(x)
end

In Plots’ case, you could probably get almost all of the benefits of precompilation like this:

foo_code = parse("foo.jl")
load_foo() = eval(foo_code)
# instead of include("foo_code.jl") directly