br-parser-tools/notes/mred/mred.txt

About PLT MrEd



Matthew Flatt
mflatt@cs.rice.edu
Rice University



Version 50
August 1997





Copyright notice



Copyright (c)1995-97 Matthew Flatt

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose is hereby granted without fee, provided
that the above copyright notice, author statement and this permission
notice appear in all copies of this software and related documentation.

THE SOFTWARE IS PROVIDED ``AS-IS'' AND WITHOUT WARRANTY OF ANY KIND,
EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

IN NO EVENT SHALL MATTHEW FLATT OR RICE UNIVERITY BE LIABLE FOR ANY
SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND, OR
ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY
OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.

wxWindows: Copyright (c)1994 Artificial Intelligence Applications
Institute, The University of Edinburgh. All rights reserved.

libscheme: Copyright (c)1994 Brent Benson. All rights reserved.

Conservative garbage collector: Copyright (c)1988, 1989 Hans-J.
Boehm, Alan J. Demers. Copyright (c)1991-1994 by Xerox Corporation.
All rights reserved.

Collector C++ extension by Jesse Hull and John Ellis: Copyright
(c)1994 by Xerox Corporation. All rights reserved.





Contents

   * This Manual
        * Thanks
   * About MrEd
        * What is MrEd?
        * What is MrEd Used For?
        * How was MrEd Developed?
        * Comparisons to Other Systems
        * Distribution
        * More Information
   * Compiling MrEd
   * Running MrEd
   * Index



This Manual



This manual explains what MrEd is and why MrEd might be useful. Complete
information for MrEd is in PLT MrEd: Graphical Toolbox Manual
../toolbox/index.htm.



Thanks



  Many thanks to Julian Smart for wxWindows and his help.
Thanks also to Brent Benson for libscheme , and to Hans Boehm and John
Ellis for the conservative garbage collector and their help. MrEd would
not be possible without these fine packages.

Thanks also to Robby Findler, Shriram Krishnamurthi, Cormac Flanagan,
Matthias Felleisen, Gann Bierner, Richard Cobbe, Dan Grossman, Stephanie
Weirich, Sebastian Good, Johnathan Franklin, Mark Krentel, Corky
Cartwright, Michael Ernst, Kennis Koldewyn, Bruce Duba, and many others
for feedback and help.

Some basic typesetting sources for this manual are taken from Julian
Smart's Reference Manual for wxWindows 1.60: a portable C++ GUI toolkit
.



About MrEd





What is MrEd?



 MrEd is a new architecture for developing portable graphical user
interface (GUI) applications. MrEd provides the developer with a modern,
high-level language supporting classes and objects, compilation units,
execptions, pre-emptive threads, run-time safety, and automatic memory
management. The language is integrated with an extensive, class-based
GUI toolbox including frames, menus, controls, multimedia text editors,
click-and-drag pasteboards, mulitple event spaces ("event loops"), and
automatic geometry management.

MrEd is based on Scheme (specifically,
MzSchemehttp://www.cs.rice.edu/CS/PLT/packages /mzscheme) with a GUI
toolbox that runs under X Windows, Microsoft Windows, and MacOS.
Applications written using MrEd run on all three platforms without
modification.

MrEd is the graphical and compuational engine behind DrScheme, a new
environment for developing and debugging Scheme applications. DrScheme
will eventually provide a complete integrated evironment for developing
MrEd applications.



What is MrEd Used For?



 MrEd is appropriate for developing any Scheme-based application
which needs a graphic interface. MrEd is particularly useful when the
graphic interface needs to be portable, when it needs sophisticated text
or graphics manipulation, or when it needs threads or eventspaces
(mulitple ``event loops''). MrEd is probably not appropriate for
applications with tight memory constraints.

MrEd can also be used as an editor. The system that MrEd uses to start
up provides an Emacs-like editing environment. However, the vast body of
Emacs packages has not been ported to MrEd; only Scheme mode and a
hyper-text mode have been fully implemented. As code is written to
extend the standard editor, new features can be inherited by all
applications written in MrEd.



How was MrEd Developed?



 MrEd's core Scheme implementation is
MzSchemehttp://www.cs.rice.edu/CS/PLT/packages /mzscheme, which was
derived from Brent Benson's libscheme . MzScheme uses the conservative
garbage collectorhttp://reality.sgi.com/employees/boehm_mti/gc.html from
Hans Boehm et al.

The GUI toolbox is derived from wxWindows
http://web.ukonline.co.uk/julian.smart/wxwin/, version 1.66 (or so).
MrEd's wxWindows has been debugged and developed along a largely
divergent path since early 1996. While this is unfortunate in that MrEd
and the wxWindows community can no longer collaborate on continued
development, the divergence also means that MrEd's branch of wxWindows
has stabilized.



Comparisons to Other Systems



    The GUI aspect of MrEd is much like Tcl/Tk
or STk: both provide a toolbox of graphic objects with an interactive
development language. MrEd's graphic object toolbox contains essentially
the same elements as Tk. The basic difference is that MrEd provides a
much richer ``operating system'' for developing large applications.

 There are several all GUI development system that are comparable
to MrEd in that they connect LISP or Scheme to an external GUI toolbox.
These tools are typically not portable, and the GUI toolbox tends to be
smaller or lower-level.

A list of other GUI development systems is available at:
http://www.cs.cmu.edu/afs/cs/user/bam/www/toolnames.html
http://www.cs.cmu.edu/afs/cs/user/bam/www/toolnames.html

 MrEd's editing system follows the Emacs model of extensibility:
the editor is written in its own extension language. However, there are
fundamental differences:
   * In Emacs, the extension language is a dynamically-scoped dialect of
     Lisp. Packages work in a global namespace. A single core editor is
     extended through a standard set of functions and variables.
   * In MrEd, the extension language is Scheme extended with an object
     system, and the core editor is represented by a set of classes. The
     editor can be extended Emacs-style by deriving new classes from the
     editor class, but a package is not necessarily just an extension of
     the editor. Rather, the core editor is available for use as a
     submodule within a package's larger architecture. MrEd's editor
system has the same potential for expansion as Emacs. Certainly, MrEd
would be an ideal platform for a new full-functioned editor based on the
Emacs model.



Distribution



  MrEd's source code can be freely distributed. Please read
the license agreement, as well as the license agreements for wxWindows,
libscheme, and the conservative garbage collector.

The latest distribution for MrEd can be obtained from the MrEd Home
Page: http://www.cs.rice.edu/CS/PLT/packages/mred/
http://www.cs.rice.edu/CS/PLT/packages/mred/



More Information



   Up-to-date information about MrEd can be found at
the MrEd Home Page: http://www.cs.rice.edu/CS/PLT/packages/mred/
http://www.cs.rice.edu/CS/PLT/packages/mred/



Compiling MrEd



Compiled versions of MrEd are available from the MrEd Home Page (see
section 2.6 , above). Some X Windows users will need to compile the code
from scratch (because it is impossible for us to provide compiled
executables for all platforms). Unfortunately, compiling MrEd is not a
trivial task.

  This section will describe how to compile MrEd for X
Windows under Unix, which requires around 20-30 MB of disk space. First,
download the following packages:
   * wxWindows  -- Information about wxWindows is available from
     http://web.ukonline.co.uk/julian.smart/wxwin/
     http://web.ukonline.co.uk/julian.smart/wxwin/ but to compile MrEd,
     special patched versions of wxWindows must be obtained from
     http://www.cs.rice.edu/CS/PLT/packages/mred/
     http://www.cs.rice.edu/CS/PLT/packages/mred/ MrEd works with two
     flavors of wxWindows: Motif and ``Xt''. MrEd works with these
     flavors about equally well. Most every X Windows installation can
     support the ``Xt'' version, while Motif must be purchased.
   * MrEd -- MrEd can be found at
     http://www.cs.rice.edu/CS/PLT/packages/mred/
     http://www.cs.rice.edu/CS/PLT/packages/mred/ This distribution
     includes MzScheme and the conservative garbage collector.

Set the WXDIR environment variable to the path of the wxWindows
installation. All the directories from the wxWindows installation should
be in the WXDIR directory.

In wxWindows's src/make.env , some of the variables may need to be
changed:
   * Set OPTIONS:
        * Add -DWXME_FOR_MRED=1.
        * Add -DWX_NORMALIZED_PS_FONTS=1 (Motif only)
        * Add -DWXME_LSB_FIRST=1 if the target machine represents
          integers with the least-significant byte in the lowest memory
          address. For example, this flag is needed for Intel machines,
          but not Sparc machines. MrEd will display a warning at startup
          if the flag value is incorrectly chosen.
        * Add -DOPERATOR_NEW_ARRAY if the C++ compiler uses separate new
          and new[] operators. For example, this flag is needed for gcc
          version 2.6.3, but not for version 2.5.8.
        * Add -DWXS_CANT_ASSIGN_STRUCTURES if the C++ compiler does not
          allow an assignment to copy structures. A compile-time error
          will occur if the flag is needed but not provided.
   * Add three paths to COMPPATHS in make.env: -I gc-directory , -I
     wxme-directory , and -I mzscheme-include-directory .
        * The gc-directory path lets the wxWindows compilation find the
          garbage collector header files. This directory is in the MrEd
          distribution as mred/mzscheme/gc .
        * The wxme-directory path lets MrEd find the wxme header files.
          This directory in the MrEd distribution as mred/wxme .
        * The mzscheme-include-directory lets MrEd find the MzScheme
          headers. This directory in the MrEd distribution as
          mred/mzscheme/include .
   * Probably, XLIB and/or XINCLUDE must be adjusted.
   * Possibly, other flags must be changed for your local configuration.

If you're unlucky, you'll also have to adjust the flags for compiling
MzScheme. These are in mred/mzscheme/Makefile and in
mred/mzscheme/sconfig.h . (A description for each flag is included
there.) Try compiling with the default flags unless there is a problem.

Once all of the setup files are ready, go to the main MrEd distribution
directory. Execute gnumake wx to compile wxWindows. After wxWindows has
compiled, use gnumake to compile MrEd. (You must use gnumake to compile
MrEd; the standard make will not work. Note, however, that make may
actually be gnumake on your system, as on Linux.)

Here are a few compiling hints:
   * Turn off the debugging flags in ``make.env''. This will make the
     object files and executable much smaller.
   * There may be a lot of `void * operator new (...)' defined but not
     used warnings from the compiler. Ignore them.



Running MrEd



Complete information about running MrEd is in PLT MrEd: Graphical
Toolbox Manual ../toolbox/index.htm, but this chapter provides a quick
overview of how to run MrEd.

At run-time, MrEd needs to find three directories: the system directory,
the MrEd system library collection directory, and the MzLib collection
directory. The system directory is named system ; it should be in the
same directory as the MrEd executable. The system library directory is
named mred , inside a collects sub-directory in the same directory as
the executable. Finally, the MzLib directory is named standard ; this
directory must be in a collects sub-directory that can be in either of
two places:
   * in a mzscheme directory that is in the same directory as MrEd's
     executeable (this is what you get after compiling MrEd)
   * in a mzscheme directory that is in the same directory as MrEd's
     directory (this is how the PLT distribution is configured)

The search path for MzLib is actually defined in terms of the location
of system . See PLT MrEd: Graphical Toolbox Manual ../toolbox/index.htm
for more information.

When you run MrEd, the window that appears is a console that provides a
Scheme read-eval-print loop. To evaluate an expression, type it after
the prompt and hit return. You can re-evaluate old expressions by moving
the caret to the end of the expression and hitting return (or by using
Meta-P from the current prompt). Evaluate a subexpression by hiliting it
and hitting return. To stop evaluation, type Ctl-C (Unix and Windows) or
Cmd-. (MacOS). 

To open a standard text-editing window from the console, use the ``New''
or ``Open...'' items in the ``File'' menu.

To run a few simple demo programs, use the ``Load Scheme File'' menu
item and select ``demo.ss'' in the distribution's ``demo'' directory
(with MrEd).

When MrEd starts up, it looks for a ``.mredrc'' file in the user's home
directory (``mredrc.ss'' under Windows). If such a file exists, it is
loaded (as a Scheme file) before the console is opened. Preferences
about the appearance and behaviour of MrEd can be set using the
``Preferences...'' menu item in the console's ``Edit'' menu.





Index



breaking
     Running MrEd
comparisons to other systems
     Comparisons to Other Systems
compiling
     Compiling MrEd
distribution
     Distribution
EmacsComparisons to Other Systems
how? How was MrEd Developed?
information
     More Information
pain and agony
     Compiling MrEd
STk  Comparisons to Other Systems
Tcl  Comparisons to Other Systems
thanks
     Thanks
Tk   Comparisons to Other Systems
what?What is MrEd?
when?What is MrEd Used
where?
     More Information
who? Thanks
why? 
     
     because we like you
          Distribution
     
Winterp
     Comparisons to Other Systems
WWW  More Information
wxWindows
     Compiling MrEd
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