cmd2 strives to be drop-in compatible with cmd, however there are a few
The Cmd.emptyline() function is
called when an empty line is entered in response to the prompt. By default, in
cmd if this method is not overridden, it repeats and executes the last
nonempty command entered. However, no end user we have encountered views this
as expected or desirable default behavior.
cmd2 completely ignores empty
lines and the base class
cmd.emptyline() method never gets called and thus
the empty line behavior cannot be overridden.
In cmd, the Cmd.identchars attribute
contains the string of characters accepted for command names. cmd uses those
characters to split the first “word” of the input, without requiring the user
to type a space. For example, if
identchars contained a string of all
alphabetic characters, the user could enter a command like
L20 and it would
be interpreted as the command
L with the first argument of
Since version 0.9.0,
cmd2 has ignored
identchars; the parsing logic in
cmd2 splits the command and arguments on whitespace. We opted for this
breaking change because while cmd supports unicode, using non-ascii unicode
characters in command names while simultaneously using
functionality can be somewhat painful. Requiring white space to delimit
arguments also ensures reliable operation of many other useful
features, including Completion and
Shortcuts, Aliases, and Macros.
If you really need this functionality in your app, you can add it back in by writing a Postparsing Hook.
In cmd, the Cmd.cmdqueue attribute
contains A list of queued input lines. The cmdqueue list is checked in
cmdloop() when new input is needed; if it is nonempty, its elements will be
processed in order, as if entered at the prompt.
Since version 0.9.13
cmd2 has removed support for
cmd2 supports running commands via the main
scripts, Python scripts, transcripts, and history replays, the only way to
preserve consistent behavior across these methods was to eliminate the command
queue. Additionally, reasoning about application behavior is much easier
without this queue present.