Improved by Eric Raymond.
diff --git a/Lib/cmd.py b/Lib/cmd.py
index 857bed1..366b0c9 100644
--- a/Lib/cmd.py
+++ b/Lib/cmd.py
@@ -1,4 +1,39 @@
# A generic class to build line-oriented command interpreters
+#
+# Interpreters constructed with this class obey the following conventions:
+#
+# 1. End of file on input is processed as the command 'EOF'.
+# 2. A command is parsed out of each line by collecting the prefix composed
+# of characters in the identchars member.
+# 3. A command `foo' is dispatched to a method 'do_foo()'; the do_ method
+# is passed a single argument consisting of the remainder of the line.
+# 4. Typing an empty line repeats the last command. (Actually, it calls the
+# method `emptyline', which may be overridden in a subclass.)
+# 5. There is a predefined `help' method. Given an argument `topic', it
+# calls the command `help_topic'. With no arguments, it lists all topics
+# with defined help_ functions, broken into up to three topics; documented
+# commands, miscellaneous help topics, and undocumented commands.
+# 6. The command '?' is a synonym for `help'. The command '!' is a synonym
+# for `shell', if a do_shell method exists.
+#
+# The `default' method may be overridden to intercept commands for which there
+# is no do_ method.
+#
+# The data member `self.ruler' sets the character used to draw separator lines
+# in the help messages. If empty, no ruler line is drawn. It defaults to "=".
+#
+# If the value of `self.intro' is nonempty when the cmdloop method is called,
+# it is printed out on interpreter startup. This value may be overridden
+# via an optional argument to the cmdloop() method.
+#
+# The data members `self.doc_header', `self.misc_header', and
+# `self.undoc_header' set the headers used for the help function's
+# listings of documented functions, miscellaneous topics, and undocumented
+# functions respectively.
+#
+# These interpreters use raw_input; thus, if the readline module is loaded,
+# they automatically support Emacs-like command history and editing features.
+#
import string
import sys
@@ -8,27 +43,58 @@
IDENTCHARS = string.letters + string.digits + '_'
class Cmd:
+ prompt = PROMPT
+ identchars = IDENTCHARS
+ ruler = '='
+ lastcmd = ''
+ intro = None
+ doc_header = "Documented commands (type help <topic>):"
+ misc_header = "Miscellaneous help topics:"
+ undoc_header = "Undocumented commands:"
- def __init__(self):
- self.prompt = PROMPT
- self.identchars = IDENTCHARS
- self.lastcmd = ''
-
- def cmdloop(self):
+ def cmdloop(self, intro=None):
+ self.preloop()
+ if intro != None:
+ self.intro = intro
+ if self.intro:
+ print self.intro
stop = None
while not stop:
try:
line = raw_input(self.prompt)
except EOFError:
line = 'EOF'
+ self.precmd()
stop = self.onecmd(line)
+ self.postcmd()
+ self.postloop()
+
+ def precmd(self):
+ pass
+
+ def postcmd(self):
+ pass
+
+ def preloop(self):
+ pass
+
+ def postloop(self):
+ pass
def onecmd(self, line):
line = string.strip(line)
- if not line:
- line = self.lastcmd
- else:
- self.lastcmd = line
+ if line == '?':
+ line = 'help'
+ elif line == '!':
+ if hasattr(self, 'do_shell'):
+ line = 'shell'
+ else:
+ self.default(line)
+ return
+ elif not line:
+ self.emptyline()
+ return
+ self.lastcmd = line
i, n = 0, len(line)
while i < n and line[i] in self.identchars: i = i+1
cmd, arg = line[:i], string.strip(line[i:])
@@ -41,6 +107,9 @@
return self.default(line)
return func(arg)
+ def emptyline(self):
+ return self.onecmd(self.lastcmd)
+
def default(self, line):
print '*** Unknown syntax:', line
@@ -70,17 +139,15 @@
else:
cmds_undoc.append(cmd)
print
- self.print_topics("Documented commands (type help " \
- "<topic>):",cmds_doc, 15, 80)
- self.print_topics("Miscellaneous help topics:",
- help.keys(), 15, 80)
- self.print_topics("Undocumented commands:",
- cmds_undoc, 15, 80)
+ self.print_topics(self.doc_header, cmds_doc, 15,80)
+ self.print_topics(self.misc_header, help.keys(),15,80)
+ self.print_topics(self.undoc_header, cmds_undoc, 15,80)
def print_topics(self, header, cmds, cmdlen, maxcol):
if cmds:
print header;
- print "="*len(header)
+ if self.ruler:
+ print self.ruler * len(header)
(cmds_per_line,junk)=divmod(maxcol,cmdlen)
col=cmds_per_line
for cmd in cmds: