add more elaborate workflow in hot loop tutorial

docs/src/tutorials/hot_loop.md

@@ -45,3 +45,33 @@ allocs = check_allocs(run_almost_forever!, (Vector{Float64},));
 @test isempty(allocs)
 ```
 
+
+## More complicated initialization
+In practice, a function may need to perform several distinct allocations upfront, including potentially allocating objects of potentially complicated types, like closures etc. In situations like this, the following pattern may be useful:
+```julia
+struct Workspace
+    ... # All you need to run the hot loop
+end
+
+function setup()
+    # Allocate and initialize the workspace
+    return workspace
+end
+
+function run!(workspace::Workspace)
+    ... # The hot loop
+end
+
+function run()
+    workspace = setup()
+    run!(workspace)
+end
+```
+
+Where `workspace` is either a custom struct designed to serve as a workspace for the hot loop, or simply a tuple of all the objects required.
+
+The benefit of breaking the function up into two parts which are called from a third, is that we may now create the workspace object individually, and use it to compute the type of the arguments to the `run!` function that we are interested in analyzing:
+```julia
+workspace = setup()
+allocs = check_allocs(run!, (typeof(workspace),))
+```