Init: Custom replacements in template / allow Hermes flag

Describe the Feature

Want to be able to do something like:

npx react-native init MYPROJECT --replace HERMES_PLACEHOLDER:true

or if that’s too involved, can we just add a hermes flag?

The use-case for this is helping to improve the release tester script. Right now to test Hermes on the template app, it’s a manual change to the Podfile / build.gradle

Possible Implementations

• We add something to template.config.js to allow specification of placeholders it supports:

module.exports = {
  placeholderName: 'HelloWorld',
  titlePlaceholder: 'Hello App Display Name',
  templateDir: './template',
  placeholders: [
     'HERMES_PLACEHOLDER',
  ], // or maybe an object if we need more information
};

Then we can validate the placeholders against placeholder values passed in via cli and just do string replace – similar to how we’re doing placeholderName, placeholderTitle: code pointer

Related Issues

[satya164]

@thymikee I think Bob is a bit difficult since there are several templates with different combinations which makes things complex. But for CLI with one template & placeholders, I think it should be pretty good. It’d also be useful to init from the template on CI and do a lint/typecheck to make sure it’s not malformed.

[thymikee]

Thank you! Take your time and ask when you need anything 😃