LEFTY(1) General Commands Manual 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 op-
erations. 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 pro-
gram. 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 va-
riety 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. LEFT-
YPATH 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 vari-
able.
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 de-
fault file name is out.ps.
-V Prints the version.
-? Prints the usage and exits.
SEE ALSO
lefty user guide.
LEFTY(1)
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