handle missing docstrings/__init__ in %pdoc

missing information properly prints 'no documentation', rather than
raising TypeErrors or AttributeErrors on missing values.

doctests added for these cases

closes gh-585

IPython/core/oinspect.py

@@ -1,741 +1,766 b''
 # -*- coding: utf-8 -*-
 """Tools for inspecting Python objects.
 
 Uses syntax highlighting for presenting the various information elements.
 
 Similar in spirit to the inspect module, but all calls take a name argument to
 reference the name under which an object is being read.
 """
 
 #*****************************************************************************
 #       Copyright (C) 2001-2004 Fernando Perez <[e-mail]>
 #
 #  Distributed under the terms of the BSD License.  The full license is in
 #  the file COPYING, distributed as part of this software.
 #*****************************************************************************
 
 __all__ = ['Inspector','InspectColors']
 
 # stdlib modules
 import __builtin__
 import inspect
 import linecache
 import os
 import sys
 import types
 from collections import namedtuple
 from itertools import izip_longest
 
 # IPython's own
 from IPython.core import page
 from IPython.utils import PyColorize
 from IPython.utils import io
 from IPython.utils.text import indent
 from IPython.utils.wildcard import list_namespace
 from IPython.utils.coloransi import *
 
 #****************************************************************************
 # Builtin color schemes
 
 Colors = TermColors  # just a shorthand
 
 # Build a few color schemes
 NoColor = ColorScheme(
     'NoColor',{
     'header' : Colors.NoColor,
     'normal' : Colors.NoColor  # color off (usu. Colors.Normal)
     }  )
 
 LinuxColors = ColorScheme(
     'Linux',{
     'header' : Colors.LightRed,
     'normal' : Colors.Normal  # color off (usu. Colors.Normal)
     } )
 
 LightBGColors = ColorScheme(
     'LightBG',{
     'header' : Colors.Red,
     'normal' : Colors.Normal  # color off (usu. Colors.Normal)
     }  )
 
 # Build table of color schemes (needed by the parser)
 InspectColors = ColorSchemeTable([NoColor,LinuxColors,LightBGColors],
                                  'Linux')
 
 #****************************************************************************
 # Auxiliary functions and objects
 
 # See the messaging spec for the definition of all these fields.  This list
 # effectively defines the order of display
 info_fields = ['type_name', 'base_class', 'string_form', 'namespace',
                'length', 'file', 'definition', 'docstring', 'source',
                'init_definition', 'class_docstring', 'init_docstring',
                'call_def', 'call_docstring',
                # These won't be printed but will be used to determine how to
                # format the object
                'ismagic', 'isalias', 'isclass', 'argspec', 'found', 'name'
                ]
 
 
 def object_info(**kw):
     """Make an object info dict with all fields present."""
     infodict = dict(izip_longest(info_fields, [None]))
     infodict.update(kw)
     return infodict
 
 
 def getdoc(obj):
     """Stable wrapper around inspect.getdoc.
 
     This can't crash because of attribute problems.
 
     It also attempts to call a getdoc() method on the given object.  This
     allows objects which provide their docstrings via non-standard mechanisms
     (like Pyro proxies) to still be inspected by ipython's ? system."""
 
     ds = None  # default return value
     try:
         ds = inspect.getdoc(obj)
     except:
         # Harden against an inspect failure, which can occur with
         # SWIG-wrapped extensions.
         pass
     # Allow objects to offer customized documentation via a getdoc method:
     try:
         ds2 = obj.getdoc()
     except:
         pass
     else:
         # if we get extra info, we add it to the normal docstring.
         if ds is None:
             ds = ds2
         else:
             ds = '%s\n%s' % (ds,ds2)
     return ds
 
 
 def getsource(obj,is_binary=False):
     """Wrapper around inspect.getsource.
 
     This can be modified by other projects to provide customized source
     extraction.
 
     Inputs:
 
     - obj: an object whose source code we will attempt to extract.
 
     Optional inputs:
 
     - is_binary: whether the object is known to come from a binary source.
     This implementation will skip returning any output for binary objects, but
     custom extractors may know how to meaningfully process them."""
     
     if is_binary:
         return None
     else:
         try:
             src = inspect.getsource(obj)
         except TypeError:
             if hasattr(obj,'__class__'):
                 src = inspect.getsource(obj.__class__)
         return src
 
 def getargspec(obj):
     """Get the names and default values of a function's arguments.
 
     A tuple of four things is returned: (args, varargs, varkw, defaults).
     'args' is a list of the argument names (it may contain nested lists).
     'varargs' and 'varkw' are the names of the * and ** arguments or None.
     'defaults' is an n-tuple of the default values of the last n arguments.
 
     Modified version of inspect.getargspec from the Python Standard
     Library."""
 
     if inspect.isfunction(obj):
         func_obj = obj
     elif inspect.ismethod(obj):
         func_obj = obj.im_func
     elif hasattr(obj, '__call__'):
         func_obj = obj.__call__
     else:
         raise TypeError('arg is not a Python function')
     args, varargs, varkw = inspect.getargs(func_obj.func_code)
     return args, varargs, varkw, func_obj.func_defaults
 
 
 def format_argspec(argspec):
     """Format argspect, convenience wrapper around inspect's.
 
     This takes a dict instead of ordered arguments and calls
     inspect.format_argspec with the arguments in the necessary order.
     """
     return inspect.formatargspec(argspec['args'], argspec['varargs'],
                                  argspec['varkw'], argspec['defaults'])
 
 
 def call_tip(oinfo, format_call=True):
     """Extract call tip data from an oinfo dict.
 
     Parameters
     ----------
     oinfo : dict
 
     format_call : bool, optional
       If True, the call line is formatted and returned as a string.  If not, a
       tuple of (name, argspec) is returned.
 
     Returns
     -------
     call_info : None, str or (str, dict) tuple.
       When format_call is True, the whole call information is formattted as a
       single string.  Otherwise, the object's name and its argspec dict are
       returned.  If no call information is available, None is returned.
       
     docstring : str or None
       The most relevant docstring for calling purposes is returned, if
       available.  The priority is: call docstring for callable instances, then
       constructor docstring for classes, then main object's docstring otherwise
       (regular functions).
     """
     # Get call definition
     argspec = oinfo.get('argspec')
     if argspec is None:
         call_line = None
     else:
         # Callable objects will have 'self' as their first argument, prune
         # it out if it's there for clarity (since users do *not* pass an
         # extra first argument explicitly).
         try:
             has_self = argspec['args'][0] == 'self'
         except (KeyError, IndexError):
             pass
         else:
             if has_self:
                 argspec['args'] = argspec['args'][1:]
                 
         call_line = oinfo['name']+format_argspec(argspec)
 
     # Now get docstring.
     # The priority is: call docstring, constructor docstring, main one.
     doc = oinfo.get('call_docstring')
     if doc is None:
         doc = oinfo.get('init_docstring')
     if doc is None:
         doc = oinfo.get('docstring','')
 
     return call_line, doc
 
 
 class Inspector:
     def __init__(self, color_table=InspectColors,
                  code_color_table=PyColorize.ANSICodeColors,
                  scheme='NoColor',
                  str_detail_level=0):
         self.color_table = color_table
         self.parser = PyColorize.Parser(code_color_table,out='str')
         self.format = self.parser.format
         self.str_detail_level = str_detail_level
         self.set_active_scheme(scheme)
 
     def _getdef(self,obj,oname=''):
         """Return the definition header for any callable object.
 
         If any exception is generated, None is returned instead and the
         exception is suppressed."""
         
         try:
             # We need a plain string here, NOT unicode!
             hdef = oname + inspect.formatargspec(*getargspec(obj))
             return hdef.encode('ascii')
         except:
             return None
  
     def __head(self,h):
         """Return a header string with proper colors."""
         return '%s%s%s' % (self.color_table.active_colors.header,h,
                            self.color_table.active_colors.normal)
 
     def set_active_scheme(self,scheme):
         self.color_table.set_active_scheme(scheme)
         self.parser.color_table.set_active_scheme(scheme)
     
     def noinfo(self,msg,oname):
         """Generic message when no information is found."""
         print 'No %s found' % msg,
         if oname:
             print 'for %s' % oname
         else:
             print
             
     def pdef(self,obj,oname=''):
         """Print the definition header for any callable object.
 
         If the object is a class, print the constructor information."""
 
         if not callable(obj):
             print 'Object is not callable.'
             return
 
         header = ''
 
         if inspect.isclass(obj):
             header = self.__head('Class constructor information:\n')
             obj = obj.__init__
         elif type(obj) is types.InstanceType:
             obj = obj.__call__
 
         output = self._getdef(obj,oname)
         if output is None:
             self.noinfo('definition header',oname)
         else:
             print >>io.stdout, header,self.format(output),
 
     def pdoc(self,obj,oname='',formatter = None):
         """Print the docstring for any object.
 
         Optional:
         -formatter: a function to run the docstring through for specially
-        formatted docstrings."""
+        formatted docstrings.
+        
+        Examples
+        --------
+        
+        In [1]: class NoInit:
+           ...:     pass
+        
+        In [2]: class NoDoc:
+           ...:     def __init__(self):
+           ...:         pass
+        
+        In [3]: %pdoc NoDoc
+        No documentation found for NoDoc
+        
+        In [4]: %pdoc NoInit
+        No documentation found for NoInit
+
+        In [5]: obj = NoInit()
+        
+        In [6]: %pdoc obj
+        No documentation found for obj
+
+        In [5]: obj2 = NoDoc()
+        
+        In [6]: %pdoc obj2
+        No documentation found for obj2
+        """
 
         head = self.__head  # For convenience
+        lines = []
         ds = getdoc(obj)
         if formatter:
             ds = formatter(ds)
-        if inspect.isclass(obj):
+        if ds:
+            lines.append(head("Class Docstring:"))
+            lines.append(indent(ds))
+        if inspect.isclass(obj) and hasattr(obj, '__init__'):
             init_ds = getdoc(obj.__init__)
-            output = "\n".join([head("Class Docstring:"),
-                                indent(ds),
-                                head("Constructor Docstring:"),
-                                indent(init_ds)])
+            if init_ds is not None:
+                lines.append(head("Constructor Docstring:"))
+                lines.append(indent(init_ds))
         elif (type(obj) is types.InstanceType or isinstance(obj,object)) \
                  and hasattr(obj,'__call__'):
             call_ds = getdoc(obj.__call__)
             if call_ds:
-                output = "\n".join([head("Class Docstring:"),
-                                    indent(ds),
-                                    head("Calling Docstring:"),
-                                    indent(call_ds)])
-            else:
-                output = ds
-        else:
-            output = ds
-        if output is None:
+                lines.append(head("Calling Docstring:"))
+                lines.append(indent(call_ds))
+
+        if not lines:
             self.noinfo('documentation',oname)
-            return
-        page.page(output)
+        else:
+            page.page('\n'.join(lines))
     
     def psource(self,obj,oname=''):
         """Print the source code for an object."""
 
         # Flush the source cache because inspect can return out-of-date source
         linecache.checkcache()
         try:
             src = getsource(obj) 
         except:
             self.noinfo('source',oname)
         else:
             page.page(self.format(src))
 
     def pfile(self,obj,oname=''):
         """Show the whole file where an object was defined."""
 
         try:
             try:
                 lineno = inspect.getsourcelines(obj)[1]
             except TypeError:
                 # For instances, try the class object like getsource() does
                 if hasattr(obj,'__class__'):
                     lineno = inspect.getsourcelines(obj.__class__)[1]
                     # Adjust the inspected object so getabsfile() below works
                     obj = obj.__class__
         except:
             self.noinfo('file',oname)
             return
 
         # We only reach this point if object was successfully queried
         
         # run contents of file through pager starting at line
         # where the object is defined
         ofile = inspect.getabsfile(obj)
 
         if ofile.endswith(('.so', '.dll', '.pyd')):
             print 'File %r is binary, not printing.' % ofile
         elif not os.path.isfile(ofile):
             print 'File %r does not exist, not printing.' % ofile
         else:
             # Print only text files, not extension binaries.  Note that
             # getsourcelines returns lineno with 1-offset and page() uses
             # 0-offset, so we must adjust.
             page.page(self.format(open(ofile).read()),lineno-1)
             
     def _format_fields(self, fields, title_width=12):
         """Formats a list of fields for display.
         
         Parameters
         ----------
         fields : list
           A list of 2-tuples: (field_title, field_content)
         title_width : int
           How many characters to pad titles to. Default 12.
         """
         out = []
         header = self.__head
         for title, content in fields:
             if len(content.splitlines()) > 1:
                 title = header(title + ":") + "\n"
             else:
                 title = header((title+":").ljust(title_width))
             out.append(title + content)
         return "\n".join(out)
 
     # The fields to be displayed by pinfo: (fancy_name, key_in_info_dict)
     pinfo_fields1 = [("Type", "type_name"),
                     ("Base Class", "base_class"),
                     ("String Form", "string_form"),
                     ("Namespace", "namespace"),
                     ("Length", "length"),
                     ("File", "file"),
                     ("Definition", "definition")]
     
     pinfo_fields_obj = [("Class Docstring", "class_docstring"),
                         ("Constructor Docstring","init_docstring"),
                         ("Call def", "call_def"),
                         ("Call docstring", "call_docstring")]
                     
     def pinfo(self,obj,oname='',formatter=None,info=None,detail_level=0):
         """Show detailed information about an object.
 
         Optional arguments:
         
         - oname: name of the variable pointing to the object.
 
         - formatter: special formatter for docstrings (see pdoc)
 
         - info: a structure with some information fields which may have been
         precomputed already.
 
         - detail_level: if set to 1, more information is given.
         """
         info = self.info(obj, oname=oname, formatter=formatter,
                             info=info, detail_level=detail_level)
         displayfields = []
         for title, key in self.pinfo_fields1:
             field = info[key]
             if field is not None:
                 displayfields.append((title, field.rstrip()))
         
         # Source or docstring, depending on detail level and whether
         # source found.
         if detail_level > 0 and info['source'] is not None:
             displayfields.append(("Source", info['source']))
         elif info['docstring'] is not None:
             displayfields.append(("Docstring", info["docstring"]))
         
         # Constructor info for classes
         if info['isclass']:
             if info['init_definition'] or info['init_docstring']:
                 displayfields.append(("Constructor information", ""))
                 if info['init_definition'] is not None:
                     displayfields.append((" Definition",
                                     info['init_definition'].rstrip()))
                 if info['init_docstring'] is not None:
                     displayfields.append((" Docstring",
                                         indent(info['init_docstring'])))
                                         
         # Info for objects:
         else:
             for title, key in self.pinfo_fields_obj:
                 field = info[key]
                 if field is not None:
                     displayfields.append((title, field.rstrip()))
         
         # Finally send to printer/pager:
         if displayfields:
             page.page(self._format_fields(displayfields))
 
     def info(self, obj, oname='', formatter=None, info=None, detail_level=0):
         """Compute a dict with detailed information about an object.
 
         Optional arguments:
         
         - oname: name of the variable pointing to the object.
 
         - formatter: special formatter for docstrings (see pdoc)
 
         - info: a structure with some information fields which may have been
         precomputed already.
 
         - detail_level: if set to 1, more information is given.
         """
 
         obj_type = type(obj)
 
         header = self.__head
         if info is None:
             ismagic = 0
             isalias = 0
             ospace = ''
         else:
             ismagic = info.ismagic
             isalias = info.isalias
             ospace = info.namespace
 
         # Get docstring, special-casing aliases:
         if isalias:
             if not callable(obj):
                 try:
                     ds = "Alias to the system command:\n  %s" % obj[1]
                 except:
                     ds = "Alias: " + str(obj)
             else:
                 ds = "Alias to " + str(obj)
                 if obj.__doc__:
                     ds += "\nDocstring:\n" + obj.__doc__
         else:
             ds = getdoc(obj)
             if ds is None:
                 ds = '<no docstring>'
         if formatter is not None:
             ds = formatter(ds)
 
         # store output in a dict, we initialize it here and fill it as we go
         out = dict(name=oname, found=True, isalias=isalias, ismagic=ismagic)
         
         string_max = 200 # max size of strings to show (snipped if longer)
         shalf = int((string_max -5)/2)
 
         if ismagic:
             obj_type_name = 'Magic function'
         elif isalias:
             obj_type_name = 'System alias'
         else:
             obj_type_name = obj_type.__name__
         out['type_name'] = obj_type_name
 
         try:
             bclass = obj.__class__
             out['base_class'] = str(bclass)
         except: pass
 
         # String form, but snip if too long in ? form (full in ??)
         if detail_level >= self.str_detail_level:
             try:
                 ostr = str(obj)
                 str_head = 'string_form'
                 if not detail_level and len(ostr)>string_max:
                     ostr = ostr[:shalf] + ' <...> ' + ostr[-shalf:]
                     ostr = ("\n" + " " * len(str_head.expandtabs())).\
                             join(q.strip() for q in ostr.split("\n"))
                 out[str_head] = ostr
             except:
                 pass
 
         if ospace:
             out['namespace'] = ospace
 
         # Length (for strings and lists)
         try:
             out['length'] = str(len(obj))
         except: pass
 
         # Filename where object was defined
         binary_file = False
         try:
             try:
                 fname = inspect.getabsfile(obj)
             except TypeError:
                 # For an instance, the file that matters is where its class was
                 # declared.
                 if hasattr(obj,'__class__'):
                     fname = inspect.getabsfile(obj.__class__)
             if fname.endswith('<string>'):
                 fname = 'Dynamically generated function. No source code available.'
             if fname.endswith(('.so', '.dll', '.pyd')):
                 binary_file = True
             out['file'] = fname
         except:
             # if anything goes wrong, we don't want to show source, so it's as
             # if the file was binary
             binary_file = True
 
         # reconstruct the function definition and print it:
         defln = self._getdef(obj, oname)
         if defln:
             out['definition'] = self.format(defln)
 
         # Docstrings only in detail 0 mode, since source contains them (we
         # avoid repetitions).  If source fails, we add them back, see below.
         if ds and detail_level == 0:
                 out['docstring'] = ds
                 
         # Original source code for any callable
         if detail_level:
             # Flush the source cache because inspect can return out-of-date
             # source
             linecache.checkcache()
             source = None
             try:
                 try:
                     src = getsource(obj,binary_file)
                 except TypeError:
                     if hasattr(obj,'__class__'):
                         src = getsource(obj.__class__,binary_file)
                 if src is not None:
                     source = self.format(src)
                     out['source'] = source.rstrip()
             except Exception:
                 pass
                 
             if ds and source is None:
                 out['docstring'] = ds
                 
 
         # Constructor docstring for classes
         if inspect.isclass(obj):
             out['isclass'] = True
             # reconstruct the function definition and print it:
             try:
                 obj_init =  obj.__init__
             except AttributeError:
                 init_def = init_ds = None
             else:
                 init_def = self._getdef(obj_init,oname)
                 init_ds  = getdoc(obj_init)
                 # Skip Python's auto-generated docstrings
                 if init_ds and \
                        init_ds.startswith('x.__init__(...) initializes'):
                     init_ds = None
 
             if init_def or init_ds:
                 if init_def:
                     out['init_definition'] = self.format(init_def)
                 if init_ds:
                     out['init_docstring'] = init_ds
 
         # and class docstring for instances:
         else:
             # First, check whether the instance docstring is identical to the
             # class one, and print it separately if they don't coincide.  In
             # most cases they will, but it's nice to print all the info for
             # objects which use instance-customized docstrings.
             if ds:
                 try:
                     cls = getattr(obj,'__class__')
                 except:
                     class_ds = None
                 else:
                     class_ds = getdoc(cls)
                 # Skip Python's auto-generated docstrings
                 if class_ds and \
                        (class_ds.startswith('function(code, globals[,') or \
                    class_ds.startswith('instancemethod(function, instance,') or \
                    class_ds.startswith('module(name[,') ):
                     class_ds = None
                 if class_ds and ds != class_ds:
                     out['class_docstring'] = class_ds
 
             # Next, try to show constructor docstrings
             try:
                 init_ds = getdoc(obj.__init__)
                 # Skip Python's auto-generated docstrings
                 if init_ds and \
                        init_ds.startswith('x.__init__(...) initializes'):
                     init_ds = None
             except AttributeError:
                 init_ds = None
             if init_ds:
                 out['init_docstring'] = init_ds
 
             # Call form docstring for callable instances
             if hasattr(obj, '__call__'):
                 call_def = self._getdef(obj.__call__, oname)
                 if call_def is not None:
                     out['call_def'] = self.format(call_def)
                 call_ds = getdoc(obj.__call__)
                 # Skip Python's auto-generated docstrings
                 if call_ds and call_ds.startswith('x.__call__(...) <==> x(...)'):
                     call_ds = None
                 if call_ds:
                     out['call_docstring'] = call_ds
 
         # Compute the object's argspec as a callable.  The key is to decide
         # whether to pull it from the object itself, from its __init__ or
         # from its __call__ method.
         
         if inspect.isclass(obj):
             # Old-style classes need not have an __init__
             callable_obj = getattr(obj, "__init__", None)
         elif callable(obj):
             callable_obj = obj
         else:
             callable_obj = None
 
         if callable_obj:
             try:
                 args,  varargs, varkw, defaults = getargspec(callable_obj)
             except (TypeError, AttributeError):
                 # For extensions/builtins we can't retrieve the argspec
                 pass
             else:
                 out['argspec'] = dict(args=args, varargs=varargs,
                                       varkw=varkw, defaults=defaults)
 
         return object_info(**out)
 
 
     def psearch(self,pattern,ns_table,ns_search=[],
                 ignore_case=False,show_all=False):
         """Search namespaces with wildcards for objects.
 
         Arguments:
 
         - pattern: string containing shell-like wildcards to use in namespace
         searches and optionally a type specification to narrow the search to
         objects of that type.
 
         - ns_table: dict of name->namespaces for search.
 
         Optional arguments:
         
           - ns_search: list of namespace names to include in search.
 
           - ignore_case(False): make the search case-insensitive.
 
           - show_all(False): show all names, including those starting with
           underscores.
         """
         #print 'ps pattern:<%r>' % pattern # dbg
         
         # defaults
         type_pattern = 'all'
         filter = ''
 
         cmds = pattern.split()
         len_cmds  =  len(cmds)
         if len_cmds == 1:
             # Only filter pattern given
             filter = cmds[0]
         elif len_cmds == 2:
             # Both filter and type specified
             filter,type_pattern = cmds
         else:
             raise ValueError('invalid argument string for psearch: <%s>' %
                              pattern)
 
         # filter search namespaces
         for name in ns_search:
             if name not in ns_table:
                 raise ValueError('invalid namespace <%s>. Valid names: %s' %
                                  (name,ns_table.keys()))
 
         #print 'type_pattern:',type_pattern # dbg
         search_result = []
         for ns_name in ns_search:
             ns = ns_table[ns_name]
             tmp_res = list(list_namespace(ns,type_pattern,filter,
                                           ignore_case=ignore_case,
                                           show_all=show_all))
             search_result.extend(tmp_res)
         search_result.sort()
 
         page.page('\n'.join(search_result))