string-format

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Is there a way to apply a transformer to all arguments? I need this because the template string is user provided so I need a way to treat the replacements without forcing the user to write the transformer's name for each placeholder.

The library doesn't provide this functionality, but you may be able to attain it with a wrapper:

const format = require('string-format');

const transformers = {
  upper: s => s.toUpperCase(),
};

const formatWith = (f, args) => format('{} {} {}', ...args.map(f));

const formatWithByName = (name, args) => formatWith(transformers[name], args);

formatWith(transformers.upper, ['foo', 'bar', 'baz']);
// => "FOO BAR BAZ"
formatWithByName('upper', ['foo', 'bar', 'baz']);
// => "FOO BAR BAZ"

I'm not sure exactly what you have in mind, though, so this may or may not be useful. :)

Nice approach, but it think it won't be useful in my case. It's because the argument is actually a nested Object and dot notation will be used in the template string.

I've already got a way to process each value inside the object, so my problem is with unexpected property names. If the user try to access a property that doesn't exists string-format will just return an empty string:

format = require("string-format");

data = {
  a: {name: "A name"}
}

format("a.name: '{a.name}'", data); // "A name"

format("a.otherProp: '{a.otherProp}'", data); // empty string

format("b.name: {b.name}", data); // Error (expected)

Trying to access b.name throws a TypeError (which is expected and properly handled). But accessing a.otherProp will just fail silently.

I think I will fork the library. Thanks for the help anyway :)

Should I fork masteror tokenizer?

Fork master, I would say.

You're welcome to submit a pull request with your changes, though I won't necessarily accept it. The goal is to complete work on #2 and have the behaviour match Python's as closely as possible. Don't hold your breath for that, though. ;)