make pretty.max_seq_length configurable

via PlainTextFormatter.max_seq_length

IPython/core/formatters.py

@@ -589,7 +589,14 b' class PlainTextFormatter(BaseFormatter):'
     # This subclass ignores this attribute as it always need to return
     # something.
     enabled = Bool(True, config=False)
-
+    
+    max_seq_length = Integer(pretty.MAX_SEQ_LENGTH, config=True,
+        help="""Truncate large collections (lists, dicts, tuples, sets) to this size.
+        
+        Set to 0 to disable truncation.
+        """
+    )
+    
     # Look for a _repr_pretty_ methods to use for pretty printing.
     print_method = ObjectName('_repr_pretty_')
 
@@ -682,6 +689,7 b' class PlainTextFormatter(BaseFormatter):'
             # or it will cause trouble.
             printer = pretty.RepresentationPrinter(stream, self.verbose,
                 self.max_width, unicode_to_str(self.newline),
+                max_seq_length=self.max_seq_length,
                 singleton_pprinters=self.singleton_printers,
                 type_pprinters=self.type_printers,
                 deferred_pprinters=self.deferred_printers)

IPython/core/tests/test_formatters.py

@@ -338,3 +338,15 b' def test_format_config():'
         result = f(Config)
     nt.assert_is(result, None)
     nt.assert_equal(captured.stderr, "")
+
+def test_pretty_max_seq_length():
+    f = PlainTextFormatter(max_seq_length=1)
+    lis = list(range(3))
+    text = f(lis)
+    nt.assert_equal(text, '[0, ...]')
+    f.max_seq_length = 0
+    text = f(lis)
+    nt.assert_equal(text, '[0, 1, 2]')
+    text = f(list(range(1024)))
+    lines = text.splitlines()
+    nt.assert_equal(len(lines), 1024)

IPython/lib/pretty.py

@@ -123,9 +123,9 b" __all__ = ['pretty', 'pprint', 'PrettyPrinter', 'RepresentationPrinter',"
     'for_type', 'for_type_by_name']
 
 
+MAX_SEQ_LENGTH = 1000
 _re_pattern_type = type(re.compile(''))
 
-
 def _safe_getattr(obj, attr, default=None):
     """Safe version of getattr.
     
@@ -137,22 +137,22 b' def _safe_getattr(obj, attr, default=None):'
     except Exception:
         return default
 
-def pretty(obj, verbose=False, max_width=79, newline='\n'):
+def pretty(obj, verbose=False, max_width=79, newline='\n', max_seq_length=MAX_SEQ_LENGTH):
     """
     Pretty print the object's representation.
     """
     stream = StringIO()
-    printer = RepresentationPrinter(stream, verbose, max_width, newline)
+    printer = RepresentationPrinter(stream, verbose, max_width, newline, max_seq_length)
     printer.pretty(obj)
     printer.flush()
     return stream.getvalue()
 
 
-def pprint(obj, verbose=False, max_width=79, newline='\n'):
+def pprint(obj, verbose=False, max_width=79, newline='\n', max_seq_length=MAX_SEQ_LENGTH):
     """
     Like `pretty` but print to stdout.
     """
-    printer = RepresentationPrinter(sys.stdout, verbose, max_width, newline)
+    printer = RepresentationPrinter(sys.stdout, verbose, max_width, newline, max_seq_length)
     printer.pretty(obj)
     printer.flush()
     sys.stdout.write(newline)
@@ -186,7 +186,7 b' class PrettyPrinter(_PrettyPrinterBase):'
     callback method.
     """
 
-    def __init__(self, output, max_width=79, newline='\n', max_seq_length=1000):
+    def __init__(self, output, max_width=79, newline='\n', max_seq_length=MAX_SEQ_LENGTH):
         self.output = output
         self.max_width = max_width
         self.newline = newline
@@ -346,9 +346,10 b' class RepresentationPrinter(PrettyPrinter):'
     """
 
     def __init__(self, output, verbose=False, max_width=79, newline='\n',
-        singleton_pprinters=None, type_pprinters=None, deferred_pprinters=None):
+        singleton_pprinters=None, type_pprinters=None, deferred_pprinters=None,
+        max_seq_length=MAX_SEQ_LENGTH):
 
-        PrettyPrinter.__init__(self, output, max_width, newline)
+        PrettyPrinter.__init__(self, output, max_width, newline, max_seq_length=max_seq_length)
         self.verbose = verbose
         self.stack = []
         if singleton_pprinters is None: