aantn/reconstant

Share constant definitions between programming languages and make your constants constant again

Introduction

Reconstant lets you share constant and enum definitions between programming languages.

Constants are defined in a yaml file and converted to idiomatic definitions in multiple programming languages.

Supported outputs include C/CPP header files, Python3 (using the enum module), Python2, Javascript, VueMixins, Java, and Rust.

This is still a WIP. Feel free to open an issue on github with questions or a PR with support for additional languages.

Other tools

I also work on Robusta - a Kubernetes troubleshooting and automation platform. If you use Kubernetes, you'll like it.

Example

Create an input file

test.yaml

constants:
- name: SOME_CONSTANT
  value: "this is a constant string"
- name: OTHER_CONSTANT
  value: 42

enums:
- name: SomeEnum
  values:
    - A
    - B
    - C
- name: OtherEnum
  values:
    - FOO
    - BAR

outputs:
  python:
    path: autogenerated_constants.py
  javascript:
    path: autogenerated_constants.js
  c:
    path: autogenerated_constants.h
  python2:
    path: autogenerated_constants_py2.py
  vue:
    path: autogenerated_vue_constants.js
  java:
    path: AutogeneratedConstants.java

Install and run reconstant

pip install git+https://github.com/aantn/reconstant.git
reconstant test.yaml

Generated Output Files

Python

autogenerated_constants.py

# autogenerated by reconstant - do not edit!
from enum import Enum

# constants
SOME_CONSTANT = "this is a constant string"
OTHER_CONSTANT = 42

# enums
class SomeEnum(Enum):
	A = 0
	B = 1
	C = 2

class OtherEnum(Enum):
	FOO = 0
	BAR = 1

Javascript

autogenerated_constants.js

// autogenerated by reconstant - do not edit!

// constants
export const SOME_CONSTANT = "this is a constant string"
export const OTHER_CONSTANT = 42

// enums
export const SomeEnum = {
	A : 0,
	B : 1,
	C : 2,
}
export const OtherEnum = {
	FOO : 0,
	BAR : 1,
}

C/CPP

autogenerated_constants.h

// autogenerated by reconstant - do not edit!
#ifndef AUTOGENERATED_CONSTANTS_H
#define AUTOGENERATED_CONSTANTS_H

// constants
const char* SOME_CONSTANT = "this is a constant string";
const int OTHER_CONSTANT = 42;

// enums
typedef enum { A, B, C } SomeEnum;
typedef enum { FOO, BAR } OtherEnum;

#endif /* AUTOGENERATED_CONSTANTS_H */

Python2-Compatible Output

autogenerated_constants_py2.py

# autogenerated by reconstant - do not edit!

# constants
SOME_CONSTANT = "this is a constant string"
OTHER_CONSTANT = 42

# enums
SOME_ENUM_A = 0
SOME_ENUM_B = 1
SOME_ENUM_C = 2
OTHER_ENUM_FOO = 0
OTHER_ENUM_BAR = 1

Vue Mixins

autogenerated_vue_constants.py

// autogenerated by reconstant - do not edit!

// constants
export const SOME_CONSTANT = "this is a constant string"
export const OTHER_CONSTANT = 42

// enums
export const SomeEnum = {
	A : 0,
	B : 1,
	C : 2,
}

SomeEnum.Mixin = {
  created () {
      this.SomeEnum = SomeEnum
  }
}
export const OtherEnum = {
	FOO : 0,
	BAR : 1,
}

OtherEnum.Mixin = {
  created () {
      this.OtherEnum = OtherEnum
  }
}

Java

AutogeneratedConstants.java

// autogenerated by reconstant - do not edit!
public final class AutogeneratedConstants {

// constants
	public static final String SOME_CONSTANT = "this is a constant string";
	public static final int OTHER_CONSTANT = 42;

// enums
	public enum SomeEnum {
		A, 
		B, 
		C
	}
	public enum OtherEnum {
		FOO, 
		BAR
	}

}

Rust

autogenerated_constants.rs

// autogenerated by reconstant - do not edit!

// constants
pub const SOME_CONSTANT: &str = "this is a constant string";
pub const OTHER_CONSTANT: i32 = 42;

// enums
pub enum SomeEnum {
	A, 
	B, 
	C
}
pub enum OtherEnum {
	FOO, 
	BAR
}

reconstant's Issues

possible improvements: 1. common comments 2. python enums inherit int

There are two improvements that would be very beneficial:

1. Support for common comments. Currently, every file has an autogenerated comment "# autogenerated by reconstant - do not edit!". I have to modify each file to add common comments, which is time-consuming.
2. Enable Python enums to inherit int. By doing so, the enums generated by reconstant can work seamlessly with pydantic, as described in the pydantic docs here.

I would love to hear your thoughts on these improvements.

Fortran constants

If you would like to add Fortran constants, or what is called a PARAMETER in Fortran, sample syntax for the basic types is

integer, parameter :: two = 2
real, parameter :: pi = 3.1416
character (len=*), parameter :: name = "Eve"
logical, parameter :: print_progress = .false.

Support the Go language

Hi, that's a great project! How do you feel about adding Go support, is that in scope?