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1 .TH LEFTY 1
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2 .SH NAME
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3 lefty \- A Programmable Graphics Editor
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4 .SH SYNOPSIS
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5 .B lefty
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6 [
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7 .I options
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8 ] [
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9 .I file
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10 ]
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11 .SH DESCRIPTION
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12 .B lefty
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13 is a two-view graphics editor for technical pictures. This editor has
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14 no hardwired knowledge about specific picture layouts or editing operations.
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15 Each picture is described by a program that contains functions to draw the
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16 picture and functions to perform editing operations that are appropriate for
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17 the specific picture. Primitive user actions, like mouse and keyboard events,
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18 are also bound to functions in this program. Besides the graphical view of the
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19 picture itself, the editor presents a textual view of the program that
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20 describes the picture. Programmability and the two-view interface allow the
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21 editor to handle a variety of pictures, but are particularly useful for
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22 pictures used in technical contexts, e.g., graphs and trees. Also,
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23 .B lefty
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24 can communicate with other processes. This feature allows it to use existing
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25 tools to compute specific picture layouts and allows external processes to use
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26 the editor as a front end to display their data structures graphically.
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27 .SH USAGE
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28 The file name is optional. It may be
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29 .BR - ,
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30 for reading from standard input.
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31 .B lefty
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32 uses two environment variables,
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33 .B LEFTYPATH
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34 and
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35 .BR LEFTYOPTIONS .
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36 .B LEFTYPATH
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37 is a colon separated list of directories. When
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38 .B lefty
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39 tries to open a file, it searches that path for the file. When
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40 .B lefty
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41 tries to start up another process, it searches
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42 .B LEFTYPATH
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43 first, then the standard
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44 .B PATH
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45 variable.
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46 .B LEFTYOPTIONS
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47 can be used to set specific options. Options specified on the command line
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48 override options set through this variable.
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49 .SH OPTIONS
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50 .TP
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51 .B -x
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52 Instructs the editor to exit after processing
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53 .BR file .
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54 .TP
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55 .B "-e <expression>"
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56 .B <expression>
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57 is parsed and executed.
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58 .TP
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59 .B -el <num>
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60 Set error reporting level. The default value is
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61 .BR 0 .
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62 .B 0
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63 never prints any messages.
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64 .B 1
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65 prints severe errors, such as trying to return from a non function.
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66 .B 2
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67 is the most useful: it reports function calls that cannot be executed, either
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68 because there is no function, or because of argument mismatches.
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69 .B 3
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70 also warns about bad variable names.
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71 .B 4,5
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72 warn about expressions that do not return a value. Only level
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73 .B 1
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74 messages are real errors. The rest arise from legal
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75 .B lefty
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76 statements, but may be cased by some logic errors.
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77 .TP
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78 .B "-sd <num>"
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79 Specifies how much of the stack to show, when an error message is to be
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80 printed. The default value is
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81 .BR 2 .
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82 With
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83 .BR 0 ,
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84 no part of the stack is shown. With
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85 .BR 1 ,
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86 only the top stack frame is printed. With
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87 .BR 2 ,
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88 the full stack is printed.
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89 .TP
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90 .B "-sb <num>"
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91 Specifies how much of each function in the stack to show, when an error message
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92 is to be printed. The default value is
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93 .BR 2 .
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94 With
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95 .BR 0 ,
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96 no part of the function is shown. With
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97 .BR 1 ,
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98 only the line around the error is printed. With
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99 .BR 2 ,
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100 the full function body is printed.
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101 .TP
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102 .B "-df <string>"
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103 Sets the default font. This font is used whenever a requested font cannot be
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104 found. The string must be a legal X font. If string is
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105 .BR "''" ,
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106 .B lefty
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107 will draw small boxes instead of text.
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108 .TP
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109 .B "-ps <file>"
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110 Specifies a default file name for postscript files. This name is used when no
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111 name is specified in the
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112 .B createwidget
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113 call. The default file name is
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114 .BR out.ps .
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115 .TP
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116 .B -V
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117 Prints the version.
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118 .SH SEE ALSO
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119 .I lefty
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120 user guide.
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