How about providing a dummy archiver?

[orca-zhang]

Dear Matt,

Thanks to your great lib.
What I'm working is optional compressed extensions, so non-compressed ones that they do nothing about compression/decompression are included.

What would you like to have changed?

provide a dummy implementation

Why is this feature a useful, necessary, and/or important addition to this project?

easy to deal with non-compressed options

What alternatives are there, or what are you doing in the meantime to work around the lack of this feature?

DIY or writing some special hard codes

Please link to any relevant issues, pull requests, or other discussions.

maybe it will look like bellows (in v3)

type DummyArchiver struct{}

func (DummyArchiver) CheckExt(string) error { return nil }
func (DummyArchiver) Compress(in io.Reader, out io.Writer) error {
	_, err := io.Copy(out, in)
	return err
}
func (DummyArchiver) Decompress(in io.Reader, out io.Writer) error {
	_, err := io.Copy(out, in)
	return err
}

[mholt]

To clarify, are you asking about v3 or v4? Because I'm no longer developing for v3...