Merge pull request #775 from python-cmd2/dynamic_commands.py

Added a basic example for dynamically adding do_* commands in a loop

3 files changed, 36 insertions, 0 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 24063db3..59cd99fb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@
     * Fixed a bug when running a cmd2 application on Linux without Gtk libraries installed
 * Enhancements
     * No longer treating empty text scripts as an error condition
+    * Allow dynamically extending a `cmd2.Cmd` object instance with a `do_xxx` method at runtime
 
 ## 0.9.16 (August 7, 2019)
 * Bug Fixes
diff --git a/cmd2/cmd2.py b/cmd2/cmd2.py
index a0a49a51..610ec897 100755
--- a/cmd2/cmd2.py
+++ b/cmd2/cmd2.py
@@ -1596,6 +1596,10 @@ class Cmd(cmd.Cmd):
         tokens, _ = self.tokens_for_completion(line, begidx, endidx)
         return completer.complete_command(tokens, text, line, begidx, endidx)
 
+    def get_names(self):
+        """Return an alphabetized list of names comprising the attributes of the cmd2 class instance."""
+        return dir(self)
+
     def get_all_commands(self) -> List[str]:
         """Return a list of all commands"""
         return [name[len(COMMAND_FUNC_PREFIX):] for name in self.get_names()
diff --git a/examples/dynamic_commands.py b/examples/dynamic_commands.py
new file mode 100755
index 00000000..69816d40
--- /dev/null
+++ b/examples/dynamic_commands.py
@@ -0,0 +1,31 @@
+#!/usr/bin/env python3
+# coding=utf-8
+"""A simple example demonstrating how do_* commands can be created in a loop.
+"""
+import functools
+import cmd2
+COMMAND_LIST = ['foo', 'bar', 'baz']
+
+
+class CommandsInLoop(cmd2.Cmd):
+    """Example of dynamically adding do_* commands."""
+    def __init__(self):
+        super().__init__(use_ipython=True)
+
+    def send_text(self, args: cmd2.Statement, *, text: str):
+        """Simulate sending text to a server and printing the response."""
+        self.poutput(text.capitalize())
+
+    def text_help(self, *, text: str):
+        """Deal with printing help for the dynamically added commands."""
+        self.poutput("Simulate sending {!r} to a server and printing the response".format(text))
+
+
+for command in COMMAND_LIST:
+    setattr(CommandsInLoop, 'do_{}'.format(command), functools.partialmethod(CommandsInLoop.send_text, text=command))
+    setattr(CommandsInLoop, 'help_{}'.format(command), functools.partialmethod(CommandsInLoop.text_help, text=command))
+
+
+if __name__ == '__main__':
+    app = CommandsInLoop()
+    app.cmdloop()