Show method strings for many objects are overly terse

[williamjsdavis]

As a new user of the package, I was surprised by the REPL show method results for many objects in this package. Upon loading creating a VTKData object, the displayed string in the REPL read "VTKData()", making me think that I had incorrectly loaded my file and the object was empty. Only upon running the dump function on the object did I then see that I had, in fact, loaded the file correctly.

In this package, VTKFile objects have an informative show method:

ReadVTK.jl/src/ReadVTK.jl

Lines 169 to 180 in 09aea36

	function Base.show(io::IO, vtk_file::VTKFile)
	return print(io, "VTKFile(",
	"\"", vtk_file.filename, "\", ",
	"<XMLDocument>", ", ",
	"\"", vtk_file.file_type, "\", ",
	"\"", vtk_file.version, "\", ",
	"\"", vtk_file.byte_order, "\", ",
	"\"", vtk_file.compressor, "\", ",
	"<appended_data>", ", ",
	vtk_file.n_points, ", ",
	vtk_file.n_cells, ")")
	end

Slightly similarly, VTKDataArray objects have a show method that is slightly helpful:

ReadVTK.jl/src/ReadVTK.jl

Lines 657 to 659 in 09aea36

	function Base.show(io::IO, data_array::VTKDataArray)
	return print(io, "VTKDataArray(\"", data_array.name, "\")")
	end

On the other hand, the following objects have REPL show methods that I believe to be too terse:

PVTKFile objects

ReadVTK.jl/src/ReadVTK.jl

Lines 278 to 280 in 09aea36

	function Base.show(io::IO, vtk_file::PVTKFile)
	return print(io, "PVTKFile()")
	end

PVDFile objects:

ReadVTK.jl/src/ReadVTK.jl

Lines 346 to 348 in 09aea36

	function Base.show(io::IO, d::PVDFile)
	return print(io, "PVDFile()")
	end

VTKData objects:

ReadVTK.jl/src/ReadVTK.jl

Line 372 in 09aea36

Base.show(io::IO, data::VTKData) = print(io, "VTKData()")

PVTKData objects:

ReadVTK.jl/src/ReadVTK.jl

Line 388 in 09aea36

Base.show(io::IO, data::PVTKData) = print(io, "PVTKData()")

PVTKDataArray objects:

ReadVTK.jl/src/ReadVTK.jl

Line 573 in 09aea36

Base.show(io::IO, vtk_file::PVTKDataArray) = print(io, "PVTKDataArray()")

Reason changes should be made

Informative show methods help new users understand the functionality of the package, and help debugging.

Suggested changes

I suggest that the show methods for the above listed objects should show short, informative summaries. I think it's open to discussion exactly what information should be shown.

[ranocha]

Sounds reasonable. If you make a PR, we will be happy to review it and assist you.