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


                       What's New In Version 2.5?

. Essentially just a refresh:  bug fixes for EvaP_PAC, use dashes rather
  than underscores for -full-help and -usage-help.  See the change log
  in EvaP.pm.


                       What's New In Version 2.6?

. Use Term::ReadLine in EvaP_PAC if possible.


                       What's New In Version 2.7?

. Replace deprecated &shellwords with Text::ParseWords::quotewords.


                       What's New In Version 2.8?

. Fix 2 defined() warnings.


Steve Lidie, Lehigh University Computing Center, 2014/11/01.

[email protected]


                               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 2.5 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.Lehigh.EDU.  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

[email protected], 97/01/12
[email protected], 2012.04.09

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