1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
|
\section{\module{cmd} ---
Support for line-oriented command interpreters}
\declaremodule{standard}{cmd}
\sectionauthor{Eric S. Raymond}{esr@snark.thyrsus.com}
\modulesynopsis{Build line-oriented command interpreters.}
The \class{Cmd} class provides a simple framework for writing
line-oriented command interpreters. These are often useful for
test harnesses, administrative tools, and prototypes that will
later be wrapped in a more sophisticated interface.
\begin{classdesc}{Cmd}{}
A \class{Cmd} instance or subclass instance is a line-oriented
interpreter framework. There is no good reason to instantiate
\class{Cmd} itself; rather, it's useful as a superclass of an
interpreter class you define yourself in order to inherit
\class{Cmd}'s methods and encapsulate action methods.
\end{classdesc}
\subsection{Cmd Objects}
\label{Cmd-objects}
A \class{Cmd} instance has the following methods:
\begin{methoddesc}{cmdloop}{\optional{intro}}
Repeatedly issue a prompt, accept input, parse an initial prefix off
the received input, and dispatch to action methods, passing them the
remainder of the line as argument.
The optional argument is a banner or intro string to be issued before the
first prompt (this overrides the \member{intro} class member).
If the \module{readline} module is loaded, input will automatically
inherit \program{bash}-like history-list editing (e.g. \kbd{Ctrl-P}
scrolls back to the last command, \kbd{Ctrl-N} forward to the next
one, \kbd{Ctrl-F} moves the cursor to the right non-destructively,
\kbd{Ctrl-B} moves the cursor to the left non-destructively, etc.).
An end-of-file on input is passed back as the string \code{'EOF'}.
An interpreter instance will recognize a command name \samp{foo} if
and only if it has a method \method{do_foo()}. As a special case,
a line beginning with the character \character{?} is dispatched to
the method \method{do_help()}. As another special case, a line
beginning with the character \character{!} is dispatched to the
method \method{do_shell} (if such a method is defined).
All subclasses of \class{Cmd} inherit a predefined \method{do_help}.
This method, called with an argument \code{bar}, invokes the
corresponding method \method{help_bar()}. With no argument,
\method{do_help()} lists all available help topics (that is, all
commands with corresponding \method{help_*()} methods), and also lists
any undocumented commands.
\end{methoddesc}
\begin{methoddesc}{onecmd}{str}
Interpret the argument as though it had been typed in in
response to the prompt.
\end{methoddesc}
\begin{methoddesc}{emptyline}{}
Method called when an empty line is entered in response to the prompt.
If this method is not overridden, it repeats the last nonempty command
entered.
\end{methoddesc}
\begin{methoddesc}{default}{line}
Method called on an input line when the command prefix is not
recognized. If this method is not overridden, it prints an
error message and returns.
\end{methoddesc}
\begin{methoddesc}{precmd}{}
Hook method executed just before the input prompt is issued. This
method is a stub in \class{Cmd}; it exists to be overridden by
subclasses.
\end{methoddesc}
\begin{methoddesc}{postcmd}{}
Hook method executed just after a command dispatch is finished. This
method is a stub in \class{Cmd}; it exists to be overridden by
subclasses.
\end{methoddesc}
\begin{methoddesc}{preloop}{}
Hook method executed once when \method{cmdloop()} is called. This
method is a stub in \class{Cmd}; it exists to be overridden by
subclasses.
\end{methoddesc}
\begin{methoddesc}{postloop}{}
Hook method executed once when \method{cmdloop()} is about to return.
This method is a stub in \class{Cmd}; it exists to be overridden by
subclasses.
\end{methoddesc}
Instances of \class{Cmd} subclasses have some public instance variables:
\begin{memberdesc}{prompt}
The prompt issued to solicit input.
\end{memberdesc}
\begin{memberdesc}{identchars}
The string of characters accepted for the command prefix.
\end{memberdesc}
\begin{memberdesc}{lastcmd}
The last nonempty command prefix seen.
\end{memberdesc}
\begin{memberdesc}{intro}
A string to issue as an intro or banner. May be overridden by giving
the \method{cmdloop()} method an argument.
\end{memberdesc}
\begin{memberdesc}{doc_header}
The header to issue if the help output has a section for documented
commands.
\end{memberdesc}
\begin{memberdesc}{misc_header}
The header to issue if the help output has a section for miscellaneous
help topics (that is, there are \method{help_*()} methods without
corresponding \method{do_*()} methods).
\end{memberdesc}
\begin{memberdesc}{undoc_header}
The header to issue if the help output has a section for undocumented
commands (that is, there are \method{do_*()} methods without
corresponding \method{help_*()} methods).
\end{memberdesc}
\begin{memberdesc}{ruler}
The character used to draw separator lines under the help-message
headers. If empty, no ruler line is drawn. It defaults to
\character{=}.
\end{memberdesc}
|
