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 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.
- -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.