codegen.md

Code generation in DOT

Golang does not natively support generics yet. So code generation is required to generate the boilerplate implementation for values and collections.

All the code generation for DOT is implemented by the dotc package.

For example, the following code generates the Value and Collection interfaces. In addition, the corresponding Stream implementations are produced as well.

For the TODO MVC app, the following code generates the required Value types and Stream implementations.

// import fmt
// import github.com/dotchain/dot/x/dotc
// import io/ioutil

func main() {
	code, err := info.Generate()
        if err != nil {
        	panic(err)
        }
        err = ioutil.WriteFile("example/generated.go", []byte(code), 0644)
        if err != nil {
        	panic(err)
        }
}

var info = dotc.Info{
	Package: "example",
        Structs: []dotc.Struct{{
        	Recv: "t",
                Type: "Todo",
                Fields: []dotc.Field{{
                	Name: "Complete",
                        Key: "complete",
                        Type: "bool",
                }, {
                	Name: "Description",
                        Key: "desc",
                        Type: "string",
                }},
        }},
        StructStreams: []dotc.Struct{{
        	Recv: "t",
                Type: "Todo",
                Fields: []dotc.Field{{
                	Name: "Complete",
                        Key: "complete",
                        Type: "bool",
                }, {
                	Name: "Description",
                        Key: "desc",
                        Type: "string",
                }},
        }},
        Slices: []dotc.Slice{{
        	Recv: "t",
               	Type: "TodoList",
               	ElemType: "Todo",
        }},
        SliceStreams: []dotc.Slice{{
        	Recv: "t",
               	Type: "TodoList",
               	ElemType: "Todo",
        }},
}

As the example above shows, code generation requires explicitly specifying the types needed. It is possible to guess these directly from the sources but that is not yet implemented

Markdown to code

This markdown can be executed to spit out the generated code like so:

$ go get github.com/tvastar/test/cmd/testmd
$ testmd -pkg main codegen.md