| If you want to write an option parser, and have it be good, there are |
| two ways to do it. The Right Way, and the Wrong Way. |
| |
| The Wrong Way is to sit down and write an option parser. We've all done |
| that. |
| |
| The Right Way is to write some complex configurable program with so many |
| options that you hit the limit of your frustration just trying to |
| manage them all, and defer it with duct-tape solutions until you see |
| exactly to the core of the problem, and finally snap and write an |
| awesome option parser. |
| |
| If you want to write an option parser, don't write an option parser. |
| Write a package manager, or a source control system, or a service |
| restarter, or an operating system. You probably won't end up with a |
| good one of those, but if you don't give up, and you are relentless and |
| diligent enough in your procrastination, you may just end up with a very |
| nice option parser. |
| |
| ## USAGE |
| |
| // my-program.js |
| var nopt = require("nopt") |
| , Stream = require("stream").Stream |
| , path = require("path") |
| , knownOpts = { "foo" : [String, null] |
| , "bar" : [Stream, Number] |
| , "baz" : path |
| , "bloo" : [ "big", "medium", "small" ] |
| , "flag" : Boolean |
| , "pick" : Boolean |
| , "many1" : [String, Array] |
| , "many2" : [path] |
| } |
| , shortHands = { "foofoo" : ["--foo", "Mr. Foo"] |
| , "b7" : ["--bar", "7"] |
| , "m" : ["--bloo", "medium"] |
| , "p" : ["--pick"] |
| , "f" : ["--flag"] |
| } |
| // everything is optional. |
| // knownOpts and shorthands default to {} |
| // arg list defaults to process.argv |
| // slice defaults to 2 |
| , parsed = nopt(knownOpts, shortHands, process.argv, 2) |
| console.log(parsed) |
| |
| This would give you support for any of the following: |
| |
| ```bash |
| $ node my-program.js --foo "blerp" --no-flag |
| { "foo" : "blerp", "flag" : false } |
| |
| $ node my-program.js ---bar 7 --foo "Mr. Hand" --flag |
| { bar: 7, foo: "Mr. Hand", flag: true } |
| |
| $ node my-program.js --foo "blerp" -f -----p |
| { foo: "blerp", flag: true, pick: true } |
| |
| $ node my-program.js -fp --foofoo |
| { foo: "Mr. Foo", flag: true, pick: true } |
| |
| $ node my-program.js --foofoo -- -fp # -- stops the flag parsing. |
| { foo: "Mr. Foo", argv: { remain: ["-fp"] } } |
| |
| $ node my-program.js --blatzk -fp # unknown opts are ok. |
| { blatzk: true, flag: true, pick: true } |
| |
| $ node my-program.js --blatzk=1000 -fp # but you need to use = if they have a value |
| { blatzk: 1000, flag: true, pick: true } |
| |
| $ node my-program.js --no-blatzk -fp # unless they start with "no-" |
| { blatzk: false, flag: true, pick: true } |
| |
| $ node my-program.js --baz b/a/z # known paths are resolved. |
| { baz: "/Users/isaacs/b/a/z" } |
| |
| # if Array is one of the types, then it can take many |
| # values, and will always be an array. The other types provided |
| # specify what types are allowed in the list. |
| |
| $ node my-program.js --many1 5 --many1 null --many1 foo |
| { many1: ["5", "null", "foo"] } |
| |
| $ node my-program.js --many2 foo --many2 bar |
| { many2: ["/path/to/foo", "path/to/bar"] } |
| ``` |
| |
| Read the tests at the bottom of `lib/nopt.js` for more examples of |
| what this puppy can do. |
| |
| ## Types |
| |
| The following types are supported, and defined on `nopt.typeDefs` |
| |
| * String: A normal string. No parsing is done. |
| * path: A file system path. Gets resolved against cwd if not absolute. |
| * url: A url. If it doesn't parse, it isn't accepted. |
| * Number: Must be numeric. |
| * Date: Must parse as a date. If it does, and `Date` is one of the options, |
| then it will return a Date object, not a string. |
| * Boolean: Must be either `true` or `false`. If an option is a boolean, |
| then it does not need a value, and its presence will imply `true` as |
| the value. To negate boolean flags, do `--no-whatever` or `--whatever |
| false` |
| * NaN: Means that the option is strictly not allowed. Any value will |
| fail. |
| * Stream: An object matching the "Stream" class in node. Valuable |
| for use when validating programmatically. (npm uses this to let you |
| supply any WriteStream on the `outfd` and `logfd` config options.) |
| * Array: If `Array` is specified as one of the types, then the value |
| will be parsed as a list of options. This means that multiple values |
| can be specified, and that the value will always be an array. |
| |
| If a type is an array of values not on this list, then those are |
| considered valid values. For instance, in the example above, the |
| `--bloo` option can only be one of `"big"`, `"medium"`, or `"small"`, |
| and any other value will be rejected. |
| |
| When parsing unknown fields, `"true"`, `"false"`, and `"null"` will be |
| interpreted as their JavaScript equivalents. |
| |
| You can also mix types and values, or multiple types, in a list. For |
| instance `{ blah: [Number, null] }` would allow a value to be set to |
| either a Number or null. When types are ordered, this implies a |
| preference, and the first type that can be used to properly interpret |
| the value will be used. |
| |
| To define a new type, add it to `nopt.typeDefs`. Each item in that |
| hash is an object with a `type` member and a `validate` method. The |
| `type` member is an object that matches what goes in the type list. The |
| `validate` method is a function that gets called with `validate(data, |
| key, val)`. Validate methods should assign `data[key]` to the valid |
| value of `val` if it can be handled properly, or return boolean |
| `false` if it cannot. |
| |
| You can also call `nopt.clean(data, types, typeDefs)` to clean up a |
| config object and remove its invalid properties. |
| |
| ## Error Handling |
| |
| By default, nopt outputs a warning to standard error when invalid values for |
| known options are found. You can change this behavior by assigning a method |
| to `nopt.invalidHandler`. This method will be called with |
| the offending `nopt.invalidHandler(key, val, types)`. |
| |
| If no `nopt.invalidHandler` is assigned, then it will console.error |
| its whining. If it is assigned to boolean `false` then the warning is |
| suppressed. |
| |
| ## Abbreviations |
| |
| Yes, they are supported. If you define options like this: |
| |
| ```javascript |
| { "foolhardyelephants" : Boolean |
| , "pileofmonkeys" : Boolean } |
| ``` |
| |
| Then this will work: |
| |
| ```bash |
| node program.js --foolhar --pil |
| node program.js --no-f --pileofmon |
| # etc. |
| ``` |
| |
| ## Shorthands |
| |
| Shorthands are a hash of shorter option names to a snippet of args that |
| they expand to. |
| |
| If multiple one-character shorthands are all combined, and the |
| combination does not unambiguously match any other option or shorthand, |
| then they will be broken up into their constituent parts. For example: |
| |
| ```json |
| { "s" : ["--loglevel", "silent"] |
| , "g" : "--global" |
| , "f" : "--force" |
| , "p" : "--parseable" |
| , "l" : "--long" |
| } |
| ``` |
| |
| ```bash |
| npm ls -sgflp |
| # just like doing this: |
| npm ls --loglevel silent --global --force --long --parseable |
| ``` |
| |
| ## The Rest of the args |
| |
| The config object returned by nopt is given a special member called |
| `argv`, which is an object with the following fields: |
| |
| * `remain`: The remaining args after all the parsing has occurred. |
| * `original`: The args as they originally appeared. |
| * `cooked`: The args after flags and shorthands are expanded. |
| |
| ## Slicing |
| |
| Node programs are called with more or less the exact argv as it appears |
| in C land, after the v8 and node-specific options have been plucked off. |
| As such, `argv[0]` is always `node` and `argv[1]` is always the |
| JavaScript program being run. |
| |
| That's usually not very useful to you. So they're sliced off by |
| default. If you want them, then you can pass in `0` as the last |
| argument, or any other number that you'd like to slice off the start of |
| the list. |