From eee6bf15805fa8ed3ca713a4c6e8edfd9ebc5d4e Mon Sep 17 00:00:00 2001
From: Kevin Van Brunt <kmvanbrunt@gmail.com>
Date: Tue, 19 Nov 2019 22:24:13 -0500
Subject: Added capability to override the argument parser class used by cmd2
 built-in commands

---
 examples/custom_parser.py   | 35 +++++++++++++++++++++++++++++++++++
 examples/override_parser.py | 24 ++++++++++++++++++++++++
 2 files changed, 59 insertions(+)
 create mode 100644 examples/custom_parser.py
 create mode 100755 examples/override_parser.py

(limited to 'examples')

diff --git a/examples/custom_parser.py b/examples/custom_parser.py
new file mode 100644
index 00000000..efeb362e
--- /dev/null
+++ b/examples/custom_parser.py
@@ -0,0 +1,35 @@
+# coding=utf-8
+"""
+Defines the CustomParser used with override_parser.py example
+"""
+import sys
+
+from cmd2 import Cmd2ArgumentParser, set_default_argument_parser
+from cmd2.ansi import style_warning
+
+
+# First define the parser
+class CustomParser(Cmd2ArgumentParser):
+    """Overrides error class"""
+    def __init__(self, *args, **kwargs) -> None:
+        super().__init__(*args, **kwargs)
+
+    def error(self, message: str) -> None:
+        """Custom override that applies custom formatting to the error message"""
+        lines = message.split('\n')
+        linum = 0
+        formatted_message = ''
+        for line in lines:
+            if linum == 0:
+                formatted_message = 'Error: ' + line
+            else:
+                formatted_message += '\n       ' + line
+            linum += 1
+
+        self.print_usage(sys.stderr)
+        formatted_message = style_warning(formatted_message)
+        self.exit(2, '{}\n\n'.format(formatted_message))
+
+
+# Now set the default parser for a cmd2 app
+set_default_argument_parser(CustomParser)
diff --git a/examples/override_parser.py b/examples/override_parser.py
new file mode 100755
index 00000000..ddfa8323
--- /dev/null
+++ b/examples/override_parser.py
@@ -0,0 +1,24 @@
+#!/usr/bin/env python
+# coding=utf-8
+# flake8: noqa F402
+"""
+The standard parser used by cmd2 built-in commands is Cmd2ArgumentParser.
+The following code shows how to override it with your own parser class.
+"""
+
+# First set a value called argparse.cmd2_parser_module with the module that defines the custom parser
+# See the code for custom_parser.py. It simply defines a parser and calls cmd2.set_default_argument_parser()
+# with the custom parser's type.
+import argparse
+argparse.cmd2_parser_module = 'examples.custom_parser'
+
+# Next import stuff from cmd2. It will import your module just before the cmd2.Cmd class file is imported
+# and therefore override the parser class it uses on its commands.
+from cmd2 import cmd2
+
+if __name__ == '__main__':
+    import sys
+    app = cmd2.Cmd(use_ipython=True, persistent_history_file='cmd2_history.dat')
+    app.locals_in_py = True     # Enable access to "self" within the py command
+    app.debug = True            # Show traceback if/when an exception occurs
+    sys.exit(app.cmdloop())
-- 
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