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lefty \- A Programmable Graphics Editor
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is a two-view graphics editor for technical pictures. This editor has
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no hardwired knowledge about specific picture layouts or editing operations.
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Each picture is described by a program that contains functions to draw the
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picture and functions to perform editing operations that are appropriate for
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the specific picture. Primitive user actions, like mouse and keyboard events,
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are also bound to functions in this program. Besides the graphical view of the
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picture itself, the editor presents a textual view of the program that
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describes the picture. Programmability and the two-view interface allow the
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editor to handle a variety of pictures, but are particularly useful for
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pictures used in technical contexts, e.g., graphs and trees. Also,
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can communicate with other processes. This feature allows it to use existing
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tools to compute specific picture layouts and allows external processes to use
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the editor as a front end to display their data structures graphically.
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The file name is optional. It may be
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for reading from standard input.
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uses two environment variables,
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is a colon separated list of directories. When
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tries to open a file, it searches that path for the file. When
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tries to start up another process, it searches
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first, then the standard
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can be used to set specific options. Options specified on the command line
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override options set through this variable.
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Instructs the editor to exit after processing
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is parsed and executed.
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Set error reporting level. The default value is
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never prints any messages.
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prints severe errors, such as trying to return from a non function.
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is the most useful: it reports function calls that cannot be executed, either
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because there is no function, or because of argument mismatches.
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also warns about bad variable names.
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warn about expressions that do not return a value. Only level
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messages are real errors. The rest arise from legal
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statements, but may be cased by some logic errors.
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Specifies how much of the stack to show, when an error message is to be
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printed. The defualt value is
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no part of the stack is shown. With
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only the top stack frame is printed. With
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the full stack is printed.
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Specifies how much of each function in the stack to show, when an error message
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is to be printed. The default value is
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no part of the function is shown. With
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only the line around the error is printed. With
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the full function body is printed.
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Sets the default font. This font is used whenever a requested font cannot be
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found. The string must be a legal X font. If string is
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will draw small boxes instead of text.
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Specifies a default file name for postscript files. This name is used when no
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name is specified in the
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call. The default file name is
added
removed
lefty/lefty.1
