From 673e53310ce16220ccc235eb0da56df9f654df4f 2012-06-12 04:14:18
From: Fernando Perez <fernando.perez@berkeley.edu>
Date: 2012-06-12 04:14:18
Subject: [PATCH] Merge pull request #1921 from bfroehle/_1890_magic_arguments_docstring

magic_arguments: dedent but otherwise preserve indentation.

Previously magic_arguments stripped all whitespace at the beginning of each line, interfering with formatting syntax which relies on indentation to give context (e.g., code blocks). Now the docstring text is passed through dedent to strip the global indentation before being handed off to `RawDescriptionHelpFormatter` which preserves any remaining indentation.

Thanks to @rkern for suggesting the solution approach.

Closes gh-1890.
---

diff --git a/IPython/core/magic_arguments.py b/IPython/core/magic_arguments.py
index 8ec2335..ca83da9 100644
--- a/IPython/core/magic_arguments.py
+++ b/IPython/core/magic_arguments.py
@@ -50,7 +50,13 @@ arguments::
 from IPython.external import argparse
 from IPython.core.error import UsageError
 from IPython.utils.process import arg_split
+from IPython.utils.text import dedent
 
+class MagicHelpFormatter(argparse.RawDescriptionHelpFormatter):
+    """ A HelpFormatter which dedents but otherwise preserves indentation.
+    """
+    def _fill_text(self, text, width, indent):
+        return argparse.RawDescriptionHelpFormatter._fill_text(self, dedent(text), width, indent)
 
 class MagicArgumentParser(argparse.ArgumentParser):
     """ An ArgumentParser tweaked for use by IPython magics.
@@ -62,7 +68,7 @@ class MagicArgumentParser(argparse.ArgumentParser):
                  epilog=None,
                  version=None,
                  parents=None,
-                 formatter_class=argparse.HelpFormatter,
+                 formatter_class=MagicHelpFormatter,
                  prefix_chars='-',
                  argument_default=None,
                  conflict_handler='error',