Gaffer-Generator

My old Gaffer is tired of writing code, so he generates it instead! This is how he does it.

Requirements

Install the latest LTS of NodeJS. Or a version around v8.11.3. Or try whatever you've got installed already, maybe it will work! https://nodejs.org/en/

Also install yarn. Or don't, and use npm instead. https://yarnpkg.com/en/

yarn global add gaffer-generator

or

npm install -g gaffer-generator

Alternatively, npx is a useful way to run this. https://www.npmjs.com/package/npx

Let's see it in action!

This project is written in a platform and language agnostic way. It contains several limited scripts that find your templates, and then it generates code based on them.

You'll have an easier time understanding it if you see it in action, so do the following:

> mkdir testing-gaffer-generator
> cd testing-gaffer-generator
> gaffer-generator create
> gaffer-generator generate

You should see output similar to the following:

> gaffer-generator generate

[15:20:31] creating: sample.output/date-parser.ts
[15:20:31] creating: sample.output/is-set.ts
[15:20:31] creating: sample.output/models/day-of-week.ts
[15:20:31] creating: sample.output/models/address.ts
[15:20:31] creating: sample.output/models/geo-point.ts
[15:20:31] creating: sample.output/models/geo-polygon.ts
[15:20:31] creating: sample.output/models/geo-rectangle.ts
[15:20:31] creating: sample.output/models/page-index.ts
[15:20:31] creating: sample.output/models/paging.ts
[15:20:31] creating: sample.output/models/index.ts
[15:20:31] creating: sample.output/services/address.service.ts
[15:20:31] creating: sample.output/services/index.ts
[15:20:31] Finished 'default' after 341 ms

What happened?

Let's break down the discrete steps that happened above:

1. We search the current directory recursively for .templateroot directories.
2. When one is found, we read in the template.js file (it should be a CommonJS module).
3. Call the download method of this file, which should return a promise that eventually resolves to any JSON describing what you want to generate.
4. Using the exported into property from the template.js, we'll recursively look at all of the other files within the .templateroot.
5. When we find a directory, recurse in to it!
6. When we find a file, parse it as a lodash template. The context will be whatever was returned from the download promise above, plus any exported methods of our template.js will be exposed on the utils object.
7. When we find a variable in the path, like _fileName_.ts, evaluate it based on our context from download.
8. When we find a _each in the path, like _eachEnum.fileName_.ts, expand it out. This lets us generate many files from a single template.

How do I get started?

Create a sample.templateroot in your project:

gaffer-generator create path/where/you/want/your/clientsdk.templateroot

Keep it under source control, and update it to generate based on your own metadata JSON, and desired client language.

It's also recommended that the generated output be placed under source control. This way, whenever you generate new code, you can see exactly what changed.

When you want to generate code, run gaffer-generator generate within that project. Point it at the root of your project, and enjoy your newly generated code! (Tip: you can have as many .templateroots as you need.)

Flags

There are several flags you can pass. To see them, run gaffer-generator --help!

Testing

yarn test