Nah: you could wirte your own argument handler, but why?

Nah is a simple command line argument/flag/parameter handler interface for Node.js.

I created Nah as a personal learning excersize, but hopefully others will find it useful. I fully intend to make as robust as reasonably possible.

Goal

Simplify working with command line parameters. Allow Node.js scripts to access command line parameters via objects rather than trying to parse [process.argv] (http://nodejs.org/docs/latest/api/process.html#process_process_argv).

Argument definitions

For each argument, the clients must provide the following information:

• namereq - boolean: is the name required? (true false)
• parseorder - parsing order of unnamed args - lower numbers first, cannot be below 0.
  • If the name isn't required and praseorder isn't specified, unordered args will after ordered args and appear in the order they are defined by the client.
• full - full name of the arg (e.g. --wake-on-timestamp)
• short - short name of the arg (e.g. -w)
• req - boolean: if the caller must supply the arg (true [false])
• userval - boolean: if the arg takes a user-supplied value ([true] false)
  • Args w/o userval are treated as Booleans with {unset:false,default:true}
• valreq - boolean: if the caller must provide a value when arg is supplied (true [false])
• type - type of data expected ([boolean], integer, float, string, character, etc.)
• default - value if the caller supplies the arg without a value
• unset - value if the caller doesn't supply the arg (same as default if not provided)

Parameter specification schemes

Basic flags

Naw must support Windows and *Nix style syntax.

 Win: /help /? /debug  /silent
*nix: --help  --debug --silent

Shorthand

Windows and *Nix have different shorthand syntax styles.

Basic Windows shorthand is a slash (/) immediately followed by the shorthand command name. Note that this is virtually identcal to Windows' standard stynax.

Multiple Windows shortand commands follow the above syntax rules. Callers MAY provide a space between commands. The slash (/) between commands MUST be present.

  Win: del /q /s
  Win: del /q/s    // Supported by Windows, but toally weird
  Win: del /qs     // Not supported by Winodws, but useful

Basic *Nix shorthand commands begin with a single dash (-) as compared to the standard double dash (--) and are immdiately followed by a single- character command identifier.

** Multiple *Nix** shorthand commands may be provided using two different schemes. First, multiple commands can be specified using the basic shorthand syntax with a space ( ) between each basic command. Second, multiple commands can be specified by providing a single dash (-) immediatley followed by a string of single-character command identifiers. Both syntaxes achieve the same result.

 *nix: -h -d -s
 *nix: -hds

Operations on multiple entities

Command line arguments may appear in any order. Nah must be able to handle arbitrary values placed outside the scope of a given argument. It must also properly support arguments that do not take values immeidately followed by an arbitrary value.

  Win: del [arg] File-A [arg] File-B [arg]
 *nix: rm  [arg] File-A [arg] File-B [arg]

Parameter with value

Windows and *Nix use different syntaxes for

Windows uses a colon to seperate argument and value.

  Win: xcopy /d:10-24-12  

Nix uses two patterns to seperate argument and value: an equals character (=) or a space ( ).

 *nix: rm    --interactive=once

Brainstorming

Clients will want/need to

• Specify valid flags

• Set default flag values

• Interact with your args as objects, not as strings

• (are these the same?)

  • Read multiple values for a single arg name.
  • Easy handling of multiple values for a single arg? e.g. app.js --file-list=head.txt,shoulders.txt,knees.txt,toes.txt

• Let users pass in JSON obojects. (nice idea, I'm not looking forward to implementing it)

    // e.g.
    {1:"fred.xsl",2:"bob.txt"}