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)