diff --git a/.gitignore b/.gitignore
index 381e0b6..8324c30 100644
--- a/.gitignore
+++ b/.gitignore
@@ -2,3 +2,4 @@
 *.jl.*.cov
 *.jl.mem
 deps/deps.jl
+docs/build
diff --git a/docs/Project.toml b/docs/Project.toml
new file mode 100644
index 0000000..c278538
--- /dev/null
+++ b/docs/Project.toml
@@ -0,0 +1,5 @@
+[deps]
+Documenter = "e30172f5-a6a5-5a46-863b-614d45cd2de4"
+
+[compat]
+Documenter = "~0.20"
diff --git a/docs/make.jl b/docs/make.jl
new file mode 100644
index 0000000..66d362d
--- /dev/null
+++ b/docs/make.jl
@@ -0,0 +1,15 @@
+using Documenter, Classes
+
+makedocs(
+    modules = [Classes],
+	sitename = "Classes.jl",
+	pages = [
+		"Home" => "index.md",
+	],
+
+	format = Documenter.HTML(prettyurls = get(ENV, "JULIA_NO_LOCAL_PRETTY_URLS", nothing) === nothing)
+)
+
+deploydocs(
+    repo = "github.com/rjplevin/Classes.jl.git",
+)
diff --git a/docs/src/index.md b/docs/src/index.md
index daa79ac..183707e 100644
--- a/docs/src/index.md
+++ b/docs/src/index.md
@@ -201,7 +201,7 @@ using Classes
 
    # Although Foo is immutable, subclasses might not be,
    # so it's still useful to define this method.
-   function Foo(self::absclass(Foo))
+   function Foo(self::AbstractFoo)
         self.foo = 0
     end
 end
@@ -210,7 +210,7 @@ end
     bar::Int
 
     # Mutable classes can use this pattern
-    function Bar(self::Union{Nothing, absclass(Bar)}=nothing)
+    function Bar(self::Union{Nothing, AbstractBar}=nothing)
         self = (self === nothing ? new() : self)
         superclass(Bar)(self)
         Bar(self, 0)
diff --git a/src/Classes.jl b/src/Classes.jl
index a412cf7..b5d22a3 100644
--- a/src/Classes.jl
+++ b/src/Classes.jl
@@ -67,8 +67,16 @@ end
 # If a symbol is already a gensym, extract the symbol and re-gensym with it
 regensym(s) = MacroTools.isgensym(s) ? gensym(Symbol(MacroTools.gensymname(s))) : gensym(s)
 
+_cache = nothing
+
 # Return info about a class in a named tuple
 function _class_info(::Type{T}) where {T <: AbstractClass}
+    global _cache
+    _cache === nothing && (_cache = Dict())
+    haskey(_cache, T) && return _cache[T]
+
+    # @info "_class_info($T)"
+
     typ = (typeof(T) === UnionAll ? Base.unwrap_unionall(T) : T)
 
     # note: must extract symbol from type to create required expression
@@ -79,7 +87,9 @@ function _class_info(::Type{T}) where {T <: AbstractClass}
     ivars = [_translate_ivar(d, iv) for iv in ivars]      # translate types to use gensyms
     wheres = [_translate_where(d, w) for w in wheres]
 
-    return (wheres=wheres, ivars=ivars, super=superclass(typ))
+    result = (wheres=wheres, ivars=ivars, super=superclass(typ))
+    _cache[T] = result
+    return result
 end
 
 """
diff --git a/test/example.jl b/test/example.jl
new file mode 100644
index 0000000..e110623
--- /dev/null
+++ b/test/example.jl
@@ -0,0 +1,13 @@
+abstract type A end
+struct B <: A
+    i::Int
+end
+
+expr1 = :(struct Foo1 i::B end)
+
+class = B
+expr2 = :(struct Foo2 i::$class end)
+
+dump(expr1)
+
+dump(expr2)
diff --git a/test/test_classes.jl b/test/test_classes.jl
index 0e509e4..5034ebf 100644
--- a/test/test_classes.jl
+++ b/test/test_classes.jl
@@ -13,7 +13,7 @@ using Classes
 
    # Although Foo is immutable, subclasses might not be,
    # so it's still useful to define this method.
-   function Foo(self::absclass(Foo))
+   function Foo(self::AbstractFoo)
         self.foo = 0
     end
 end
@@ -28,7 +28,7 @@ end
     bar::Int
 
     # Mutable classes can use this pattern
-    function Bar(self::Union{Nothing, absclass(Bar)}=nothing)
+    function Bar(self::Union{Nothing, AbstractBar}=nothing)
         self = (self === nothing ? new() : self)
         superclass(Bar)(self)
         Bar(self, 0)