I'm writing a utility to import/export data into an API. I'd like to be
able to accept multiple input/output formats, and support multiple
commands. I was going to use kingpin for the flags/commands, and do a type
format after that.
My plan was to declare an interface with the methods I'm going to use, a
struct that's got the parameters needed for the interface, but doesn't
satisfy it, and declare a map of structs that do satisfy that interface.
type versionParams struct {
options int
sess api.Session
in io.ReadCloser
out io.WriteCloser
log *log.Logger
}
type Version interface {
Import()
Export()
Example()
}
var versions map[string]Version
In main, I'd detect the actions, and if it's one of the actions for one of
those types, create the object, load it up with input and output and stuff.
Note, because of the flags I'm using, *format is a pointer to a string
holding the format's name. So, I was thinking I'd do something like:
args := versionParams{}
// some stuff to fill in the args
args.(versions[*format]).Import()
Then, for each version I want to add, in that version I'd do something like
the following, in it's own file:
type v1csv struct {
versionParams
Version
}
func init() {
versions["v1csv"] = v1csv
}
func (v *v1csv) Import() {
// do stuff
}
func (v *v1csv) Example() {
// do stuff
}
func (v *v1csv) Export() {
// do stuff
}
I don't think this works for multiple reasons though. I don't think you can
declare a map of types that satisfy an interface like that? And once you
do, I guess I don't know if I can cast/convert from one struct to another
without directly naming the struct...? I guess I could drop the generic
versionParams struct and just create structs for each type, but I would
still want to put those struct types into a map - that's the part that I'm
stuck on figuring out.
I wanted to go with something like this layout specifically so that I could
add new formats by simply adding that one format in a self contained file.
I don't want to statically name them and
Mostly, I think I'm just lost in design and I cannot see the way out
myself. Any suggestions to help me figure out how to do this, or something
more appropriate, would be appreciated. :-)
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