Merge pull request #2210 from mcabbott/show4

Fix a bug in show

Author: mcabbott

src/layers/show.jl

@@ -77,8 +77,9 @@ function _layer_show(io::IO, layer, indent::Int=0, name=nothing)
   print(io, " "^indent, str, indent==0 ? "" : ",")
   if !isempty(params(layer))
     print(io, " "^max(2, (indent==0 ? 20 : 39) - indent - length(str)))
-    printstyled(io, "# ", underscorise(sum(length, params(layer))), " parameters"; color=:light_black)
-    nonparam = _childarray_sum(length, layer) - sum(length, params(layer))
+    printstyled(io, "# ", underscorise(sum(length, params(layer); init=0)), " parameters"; 
+color=:light_black)
+    nonparam = _childarray_sum(length, layer) - sum(length, params(layer), init=0)
     if nonparam > 0
       printstyled(io, ", plus ", underscorise(nonparam), indent==0 ? " non-trainable" : ""; color=:light_black)
     end
@@ -90,11 +91,11 @@ end
 function _big_finale(io::IO, m)
   ps = params(m)
   if length(ps) > 2
-    pars = underscorise(sum(length, ps))
+    pars = underscorise(sum(length, ps; init=0))
     bytes = Base.format_bytes(Base.summarysize(m))
     noncnt = _childarray_sum(_->1, m) - length(ps)
     if noncnt > 0
-      nonparam = underscorise(_childarray_sum(length, m) - sum(length, ps))
+      nonparam = underscorise(_childarray_sum(length, m) - sum(length, ps; init=0))
       printstyled(io, " "^08, "# Total: ", length(ps), " trainable arrays, "; color=:light_black)
       println(io, pars, " parameters,")
       printstyled(io, " "^10, "# plus ", noncnt, " non-trainable, ", nonparam, " parameters, summarysize "; color=:light_black)
@@ -107,7 +108,8 @@ function _big_finale(io::IO, m)
 end
 
 _childarray_sum(f, x::AbstractArray{<:Number}) = f(x)
-_childarray_sum(f, x) = isleaf(x) ? 0 : sum(y -> _childarray_sum(f, y), Functors.children(x))
+_childarray_sum(f, x) = isleaf(x) ? 0 : sum(y -> _childarray_sum(f, y), Functors.children(x), 
+init=0)
 
 # utility functions
 

test/layers/show.jl

@@ -73,3 +73,12 @@ end
   @test occursin("Dense(2 => 2)", adjoint_chain)
   @test occursin("Chain([", adjoint_chain)
 end
+
+# Bug when no children, https://github.com/FluxML/Flux.jl/issues/2208
+struct NoFields end
+Flux.@functor NoFields
+
+@testset "show with no fields" begin
+  str = repr("text/plain", Chain(Dense(1=>1), Dense(1=>1), NoFields()))
+  @test occursin("4 arrays, 4 parameters", str)
+end