Universal way to generate some Go code from single description (like X-Macro in...

// I was looking for some substitution for X-Macro C preprocessor trick (https://en.wikipedia.org/wiki/X_Macro). // And this method copes with a problem in a lot more straightforward and powerful way.

// X-Macro version in C: // // #define SOME_STATES(_) \ // _(SOME_STATE_NEW, "NEW") \ // _(SOME_STATE_IN_PROGRESS, "IN_PROGRESS") \ // _(SOME_STATE_DONE, "DONE") // // #define X(name, ...) name, // enum { // SOME_STATES(X) // }; // #undef X

some_states: - name: SomeStateNew val: SomeState = iota text: NEW - name: SomeStateInProgress text: IN_PROGRESS - name: SomeStateDone text: DONE

package somepkg

//go:generate sh -c "gotpl some_state.tpl -f data.yaml | gofmt >some_state.gen.go"

// for debug use: go:generate sh -c "gotpl some_state.tpl -f data.yaml | tee /dev/stderr | gofmt >some_state.gen.go"

package somepkg

import "errors"

const ( {{- range .some_states}} {{.name}} {{.val}} {{- end}} )

func (s SomeState) String() string { switch s { {{- range .some_states}} case {{.name}}: return "{{.text}}" {{- end}} } return "<unknown>" }

func Parse(s string) (SomeState, error) { switch s { {{- range .some_states}} case "{{.text}}": return {{.name}}, nil {{- end}} } return SomeState(0), errors.New("unknown some state") }

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