Library API

The command is implemented with the importable package at github.com/cohesivestack/constago/lib. Its declared Go package name is constago.

Install

go get github.com/cohesivestack/constago@v0.1.0

Import it with an explicit alias if you want the path and package name to be obvious:

import constago "github.com/cohesivestack/constago/lib"

Generate from YAML

package main

import (
  "log"

  constago "github.com/cohesivestack/constago/lib"
)

func main() {
  cfg, err := constago.LoadConfig("constago.yaml")
  if err != nil {
    log.Fatal(err)
  }

  if err := constago.Generate(cfg); err != nil {
    log.Fatal(err)
  }
}

LoadConfig reads YAML, applies defaults, and validates the result. Generate also applies defaults and validates, so passing a raw configuration is safe.

Generate from Go

package main

import (
  "log"

  constago "github.com/cohesivestack/constago/lib"
)

func main() {
  cfg := &constago.Config{
    Input: constago.ConfigInput{
      Dir:     ".",
      Include: []string{"**/*.go"},
      Exclude: []string{"**/*_test.go", "**/constago.gen.go"},
    },
    Output: constago.ConfigOutput{
      FileName: "constago.gen.go",
    },
    Elements: []constago.ConfigTag{
      {
        Name: "json",
        Input: constago.ConfigTagInput{
          Mode:        constago.InputModeTypeTag,
          TagPriority: []string{"json"},
        },
        Output: constago.ConfigTagOutput{
          Mode: constago.OutputModeConstant,
        },
      },
    },
  }

  if err := constago.Generate(cfg); err != nil {
    log.Fatal(err)
  }
}

Pointer booleans in ConfigInputStruct, ConfigInputField, and ConfigTagOutputTransform distinguish an omitted value from an explicit false. If they are nil, NewConfig supplies defaults.

Validate and inspect defaults

cfg, err := constago.NewConfig(raw)
if err != nil {
  return err
}

NewConfig mutates and returns the supplied configuration after applying defaults. Pass a non-nil *Config.

Build a model without writing files

cfg, err := constago.NewConfig(raw)
if err != nil {
  return err
}

model, err := constago.NewModelBuilder(cfg).Build()
if err != nil {
  return err
}

fmt.Println(model.FilesScanned)
fmt.Println(model.PackagesFound)
fmt.Println(model.StructsFound)

The returned Model exposes packages, selected structs, constants, grouped accessors, getters, scan counts, and scan errors. This is useful for custom reporting or inspecting what would be generated.

Public enum constants

Use exported constants instead of raw strings in Go configuration:

Category	Constants
Input mode	InputModeTypeTag, InputModeTypeField, InputModeTypeTagThenField
Output mode	OutputModeNone, OutputModeStruct, OutputModeConstant
Identifier format	ConstantFormatCamel, ConstantFormatPascal, ConstantFormatSnake, ConstantFormatSnakeUpper
Value case	TransformCaseAsIs, TransformCaseCamel, TransformCasePascal, TransformCaseUpper, TransformCaseLower