What is Evaluate Parameters?

Briefly, EvaP() is a table driven command line argument processor that type checks values and provides up to three levels of online help on the comamnd and its parameters. You provide the Parameter Description Table (PDT), and, optionally, a help Message Module (MM), and call EvaP() with pointers to this information, and get in return an option hash with command line values indexed by argument name. When users request help, EvaP() uses the PDT and MM to present the help data and exits, all automatically.

EvaP() allows for parameter aliases, defaults values, environment variables, and handles these types:

switch, string, real, integer, boolean, file, key, application, name

Here's a sample PDT:

PDT my_program

       date, d: string = `date`
       list, l: file = stdout
       color_space, cs: key rgb, cmy, hsb, keyend = $D_CS, rgb
       scale_factor, sf: real = 1.0
       debug, d: boolena = true

PDTEND optional_file_list

What's New In Version 2.3.3?

. The C and Tcl versions of Evaluate Parameters have been removed from this special CPAN distribution, so many auxiliary features and program are not available, nor is EvaP() embeddable. Nevertheless, `genpTk' is available, a program that writes Perl/Tk code so you can wrap your EvaP() compliant application in a Perl/Tk GUI wrapper. And with luck, it'll work for your programs that don't use EvaP() as well.

. Update for Perl 5.005 and Perl/Tk 800.008.

What's New In Version 2.3.5?

. Update for Perl 5.005_03 and Perl/Tk 800.013. Fix a pager problem on MacOS. Note: test #23 has been known to fail on Win32 systems due to tab stop differences - this is not an error, per se, but, hey, what can I say? This is really version 2.3.4, but that 1 line MacOS pager fix forced me to update the version number. CPAN is watching after us!

What's New In Version 2.3.6?

. A patch from Avner Moshkovitz to handle spaces and quotes embeded in string options. 2010/01/19

Steve Lidie, Lehigh University Computing Center, 99/04/08.

sol0@Lehigh.EDU

Installation

perl Makefile.PL
make
make test
make install (as root)

Usage

. perldoc Getopt::EvaP
. genpTk -full_help

Here's the Announce file from the complete distribution:

Evaluate Parameters 2.3 for C, Perl and Tcl

Evaluate Parameters, designed as a replacement for the getopt family of functions, is now available. Briefly, Evaluate Parameters parses a Unix command line in a simple and consistent manner, performs type-checking on parameter values and provides three levels of help on the command, its parameters and their possible values.

Evaluate Parameters for C, Perl and Tcl is also embeddable in your application. This simply means that you can write an application whose subcommand processors each use Evaluate Parameters to handle their argument processing, leading to an amazingly consistent and pleasant user interface.

Evaluate Parameters has been updated for Perl 5.002+, Tcl 7.5+ and Tk 4.0+.

There are several advantages to using Evaluate Parameters in all your C, Perl and Tcl programs:

• Every program or application command calling Evaluate Parameters has a -help switch which lists all the command line arguments and their aliases, the types of parameter values they expect, and their default values. Many commands have no man pages so this first-level help is the only help available to a user. This is provided automatically as part of Evaluate Parameters; no code is required in your application. There are also two other levels of help: -usage_help and -full_help.

  An optional help Message Module can be defined to provide additional help for the command and all its parameters. This information is displayed when -full_help is specified on the command line.

• Because Evaluate Parameters allows command line arguments to have an alias, parameters can be given meaningful names which a user can readily understand. Hackers, on the other hand, can use the abbreviation to speed their work.
• Evaluate Parameters verifies that the value specified for a command line argument is of the appropriate type. Types currently supported are switch, string, real, integer, boolean, file, key, application and name.

  For C, parameter values are returned in a structure known as the PVT (Parameter Value Table) and are available in two forms; unconverted C strings and type-converted values.

  For Perl, since the language performs type conversion automatically, you simply get the parameter's value in global variables: the `old' way in variables of the form $opt_parameter and @opt_parameter, and the `new' way in the hashes %options and %Options. If you use the hashes %options or %Options Perl 5 lists are returned as a reference to a list. (Note, for evap/Perl you can optionally specify a private hash reference to hold option values, which disables this historical namespace bashing.)

  For Tcl, since the language performs type conversion automatically, you simply get the parameter's value in global variables: the `old' way in variables of the form $opt_parameter, and the `new' way in the associative array $options and $Options. If you use $Options (or $options) lists are returned as a string `joined' by the multi-dimensional array emulation character (\x1C).

• All parameter types except switch may be lists.
• Two auxiliary Perl programs called `generate_PerlTk_program' and 'generate_TclTk_program' automatically write Tk X11 GUI wrappers for any program using Evaluate Parameters. Here are the general capabilities of programs created by generate_[Perl|Tk]_program:

  . Command line parameters are specified via a form packed inside a scrollable Text widget. Most are Entry widgets, except for parameters of type switch and boolean which are Radiobutton widgets, and type key which can be either Radiobutton widgets or an Optionmenu.

  . For `list of' command line parameters we make these widget distinctions:

        key             Checkbutton widget
        switch          not allowed
        other types     Entry widget with multiple space-separated items

. Complete command and parameter help (from the Evaluate Parameters Message Module) displayed in a scrollable Text widget.

. A scrollable Entry widget dynamically displays the command to be executed.

. After execution the command's standard output is captured in a separate

     Toplevel window.  This window can be saved to a file or directed to a
     command pipeline.

. Parameters are labeled with Button widgets rather than Label widgets so

     clicking on a command line parameter Button positions the help window
     automatically to the help text for that parameter.  The scrollable Entry
     widget is also repositioned to show the specified parameter.

. Important items that should be highlighted for the user to see are

     displayed in a configurable background color using the X11 resource name
     `name.highlight : color'.          

. An Undo selection to reset all command line parameters to their original values.

. Usage help explaining the characteristics of applications generated by generate_[Perl|Tk]_program, and details of Evaluate Parameters.

• An auxiliary Perl program called `generate_man_page' automatically creates a simple nroff man page for any program using Evaluate Parameters.
• Evaluate Parameters for C interfaces cleanly with Xlib or Xt.
• Your job of developing applications is simplified because you don't waste time writing code to process arguments again, and again, and again! Command line parsing is simple, compact and consistent. Adding or changing command line parameters is extremely easy.
• Most importantly, as long as you adhere to the Human Interface Guidelines, Evaluate Parameters provides for a consistent user interface across all your C, Perl and Tcl programs.

Availability

All the implementations of Evaluate Parameters are available via anonymous FTP from ftp ftp.Lehigh.EDU (128.180.1.4). Look in the pub/evap/evap-2.x directory for the latest compressed tar file.

Evaluate Parameters/C is known to work on AIX, EP/IX, HP-UX, IRIX, Linux, Sony NEWS, SunOS, TitanOS and Ultrix. It has in the past also worked on VX/VE.

Evaluate Parameters/Perl is known to work on AIX, Linux and MS-DOS.

Evaluate Parameters/Tcl is known to work on AIX.

Stephen O. Lidie
Lehigh University Computing Center

lusol@Lehigh.EDU, 97/01/12