1LEFTY(1) General Commands Manual LEFTY(1)
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6 lefty - A Programmable Graphics Editor
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9 lefty [ options ] [ file ]
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12 lefty is a two-view graphics editor for technical pictures. This editor
13 has no hardwired knowledge about specific picture layouts or editing
14 operations. Each picture is described by a program that contains func‐
15 tions to draw the picture and functions to perform editing operations
16 that are appropriate for the specific picture. Primitive user actions,
17 like mouse and keyboard events, are also bound to functions in this
18 program. Besides the graphical view of the picture itself, the editor
19 presents a textual view of the program that describes the picture. Pro‐
20 grammability and the two-view interface allow the editor to handle a
21 variety of pictures, but are particularly useful for pictures used in
22 technical contexts, e.g., graphs and trees. Also, lefty can communicate
23 with other processes. This feature allows it to use existing tools to
24 compute specific picture layouts and allows external processes to use
25 the editor as a front end to display their data structures graphically.
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28 The file name is optional. It may be -, for reading from standard
29 input. lefty uses two environment variables, LEFTYPATH and LEFTYOP‐
30 TIONS. LEFTYPATH is a colon separated list of directories. When lefty
31 tries to open a file, it searches that path for the file. When lefty
32 tries to start up another process, it searches LEFTYPATH first, then
33 the standard PATH variable. LEFTYOPTIONS can be used to set specific
34 options. Options specified on the command line override options set
35 through this variable.
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38 -x Instructs the editor to exit after processing file.
39 -e <expression>
41 <expression> is parsed and executed.
42 -el <num>
44 Set error reporting level. The default value is 0. 0 never
45 prints any messages. 1 prints severe errors, such as trying to
46 return from a non function. 2 is the most useful: it reports
47 function calls that cannot be executed, either because there is
48 no function, or because of argument mismatches. 3 also warns
49 about bad variable names. 4,5 warn about expressions that do
50 not return a value. Only level 1 messages are real errors. The
51 rest arise from legal lefty statements, but may be cased by some
52 logic errors.
53 -sd <num>
55 Specifies how much of the stack to show, when an error message
56 is to be printed. The default value is 2. With 0, no part of
57 the stack is shown. With 1, only the top stack frame is printed.
58 With 2, the full stack is printed.
59 -sb <num>
61 Specifies how much of each function in the stack to show, when
62 an error message is to be printed. The default value is 2. With
63 0, no part of the function is shown. With 1, only the line
64 around the error is printed. With 2, the full function body is
65 printed.
66 -df <string>
68 Sets the default font. This font is used whenever a requested
69 font cannot be found. The string must be a legal X font. If
70 string is '', lefty will draw small boxes instead of text.
71 -ps <file>
73 Specifies a default file name for postscript files. This name is
74 used when no name is specified in the createwidget call. The
75 default file name is out.ps.
76 -V Prints the version.
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80 lefty user guide.
81 LEFTY(1)