Make mode "r" default for H5File

src/hdf5/hdf5.jl

@@ -40,7 +40,7 @@ struct H5File
     _h5f::HDF5.File
     _datasets::Dict{String, H5CompoundDataset}
 
-    function H5File(fname::AbstractString, mode="w")
+    function H5File(fname::AbstractString, mode="r")
         h5f = h5open(fname, mode)
         new(h5f, Dict{String, H5CompoundDataset}())
     end

test/hdf5.jl

@@ -11,7 +11,7 @@ end
     fname = tempname()
     bars = [Bar(x, x*2.1) for x ∈ 1:100]
 
-    f = H5File(fname)
+    f = H5File(fname, "w")
     d = create_dataset(f, "bars", Bar; cache_size=3)
     for bar ∈ bars
         push!(d, bar)