byname

A simple library, it lets you take a function, introspect (parse) its arguments, and invoke it with an options object instead of positional arguments.

Directly Invoking a Function

So as a basic example, here is how you would invoke a function directly using byname.invoke(targetFunction, options):

var byname = require('byname');

function someFunction(name, value) {
  console.log("name = " + name);
  console.log("value = " + value);
}

byname.invoke(someFunction, {
  name: "This is the name",
  value: "This is the value"
});

Wrapping a Function

You can also wrap the function using byname.wrap(targetFunction). This will generate a wrapper function that can be used to invoke the target function repeatedly without having to perform introspection.

var byname = require('byname');

function someFunction(name, value) {
  console.log("name = " + name);
  console.log("value = " + value);
}

var wrapped = byname.wrap(someFunction);
wrapped({
  name: "This is the name",
  value: "This is the value"
});

Trailing Arguments

If you provide explicit arguments to the wrapped function, they will serve as the trailing arguments of the target function. This is especially useful for providing a callback outside of the options object:

var byname = require('byname');

function someFunction(name, value, callback) {
  var result = "name = " + name + " / value = " + value;
  callback(null, result);
}

var wrapped = byname.wrap(someFunction);
wrapped({
  name: "This is the name",
  value: "This is the value"
}, handler);

function handler(err, result) {
  console.log(result);
}

Explicitly Naming Arguments

If you don't like the argument names you've chosen for your target function, or if it has been bound and the argument names lost, you can explicitly set the names used. It's even good for mapping some arbitrary object to a function's arguments:

var byname = require('byname');

function someFunction(name, value) {
  console.log("name = " + name);
  console.log("value = " + value);
}

var wrapped = byname.wrap(someFunction, "n", "v");
wrapped({
  n: "This is the name",
  v: "This is the value"
});

Default Argument Values

Perhaps you need default values? The wrapped function exposes a couple of utility functions, one of which is withDefaults(defaults). It returns an augmented version of the wrapper that provides defaults for any arguments not specific upon invocation:

var byname = require('byname');

function someFunction(name, value) {
  console.log("name = " + name);
  console.log("value = " + value);
}

var defaulted = byname.wrap(someFunction).withDefaults({
  value: "This is the value"
});

defaulted({
  name: "This is the name"
});

withDefaults(defaults) will accept either an object or a function that returns an object. If provided a function to generate defaults, that function will be invoked every time the wrapped function is called.

Retrieving Argument Names

The other is getArgumentNames() which can be used to return the names of the wrapped function's introspected arguments:

var byname = require('byname');

function someFunction(name, value) {
}

var wrapped = byname.wrap(someFunction);

console.log(wrapped.getArgumentNames());

Options is Optional

If you do not include an object as your first argument, any arguments specified will continue to be treated as trailing arguments, and an empty options object will be assumed:

var byname = require('byname');

function someFunction(name, value, callback) {
  var result = "name = " + name + " / value = " + value;
  callback(null, result);
}

var wrapped = byname.wrap(someFunction);
// invoke someFunction with name and value undefined
wrapped(handler);

function handler(err, result) {
  console.log(result);
}

This behavior also applies to interfaces create using withDefaults(defaults).

License (MIT License)

Copyright (c) 2015 Thomas S. Bradford

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.