


LEFTY(1)                                                 LEFTY(1)


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 func-
       tions 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. Pro-
       grammability  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  LEFTYOP-
       TIONS.   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 cased 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.



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LEFTY(1)                                                 LEFTY(1)


       -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.

SEE ALSO
       lefty user guide.




































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