NAME

       lefty - A Programmable Graphics Editor

SYNOPSIS

       lefty [ options ] [ file ]

DESCRIPTION

       lefty  is  a two-view graphics editor for technical pictures. This editor has no hardwired
       knowledge about specific picture layouts or editing operations.  Each picture is described
       by  a program that contains functions to draw the picture and functions to perform editing
       operations that are appropriate for the specific picture.  Primitive  user  actions,  like
       mouse  and  keyboard  events,  are  also  bound  to functions in this program. Besides the
       graphical view of the picture itself, the editor presents a textual view  of  the  program
       that describes the picture. Programmability and the two-view interface allow the editor to
       handle a variety of pictures, but are particularly useful for pictures used  in  technical
       contexts,  e.g.,  graphs and trees. Also, lefty can communicate with other processes. This
       feature allows it to use existing tools to compute specific  picture  layouts  and  allows
       external  processes  to  use  the  editor  as a front end to display their data structures
       graphically.

USAGE

       The file name is optional. It may be -, for reading from standard input.  lefty  uses  two
       environment variables, LEFTYPATH and LEFTYOPTIONS.  LEFTYPATH is a colon separated list of
       directories. When lefty tries to open a file, it searches that path  for  the  file.  When
       lefty  tries  to  start up another process, it searches LEFTYPATH first, then the standard
       PATH variable.  LEFTYOPTIONS can be used to set specific options. Options specified on the
       command line override options set through this variable.

OPTIONS

       -x     Instructs the editor to exit after processing file.

       -e <expression>
              <expression> is parsed and executed.

       -el <num>
              Set error reporting level. The default value is 0.  0 never prints any messages.  1
              prints severe errors, such as trying to return from a non function.  2 is the  most
              useful:  it reports function calls that cannot be executed, either because there is
              no function, or because of argument mismatches.  3 also warns  about  bad  variable
              names.   4,5  warn  about  expressions  that  do  not  return a value. Only level 1
              messages are real errors. The rest arise from legal lefty statements,  but  may  be
              caused by some logic errors.

       -sd <num>
              Specifies  how  much  of the stack to show, when an error message is to be printed.
              The default value is 2.  With 0, no part of the stack is shown. With  1,  only  the
              top stack frame is printed. With 2, the full stack is printed.

       -sb <num>
              Specifies  how much of each function in the stack to show, when an error message is
              to be printed. The default value is 2.  With 0, no part of the function  is  shown.
              With  1,  only the line around the error is printed. With 2, the full function body
              is printed.

       -df <string>
              Sets the default font. This font is used whenever a requested font cannot be found.
              The  string  must  be  a legal X font. If string is '', lefty will draw small boxes
              instead of text.

       -ps <file>
              Specifies a default file name for postscript files. This name is used when no  name
              is specified in the createwidget call. The default file name is out.ps.

       -V     Prints the version.

       -?     Prints the usage and exits.

SEE ALSO

       lefty user guide.

                                                                                         LEFTY(1)