Add optional fillchar argument to ljust(), rjust(), and center() string methods.

rhettinger · rhettinger · commit 74f9a76ccf89 · 2003-11-26T08:21:35.000Z
git-svn-id: http://svn.python.org/projects/python/trunk@34740 6015fed2-1504-0410-9fe1-9d1591cc4771
diff --git a/Doc/lib/libstdtypes.tex b/Doc/lib/libstdtypes.tex
@@ -546,9 +546,9 @@ \subsubsection{String Methods \label{string-methods}}
 Return a copy of the string with only its first character capitalized.
 \end{methoddesc}
 
-\begin{methoddesc}[string]{center}{width}
+\begin{methoddesc}[string]{center}{width\optional{, fillchar}}
 Return centered in a string of length \var{width}. Padding is done
-using spaces.
+using the specified \var{fillchar} (default is a space).
 \end{methoddesc}
 
 \begin{methoddesc}[string]{count}{sub\optional{, start\optional{, end}}}
@@ -645,9 +645,10 @@ \subsubsection{String Methods \label{string-methods}}
 providing this method.
 \end{methoddesc}
 
-\begin{methoddesc}[string]{ljust}{width}
+\begin{methoddesc}[string]{ljust}{width\optional{, fillchar}}
 Return the string left justified in a string of length \var{width}.
-Padding is done using spaces.  The original string is returned if
+Padding is done using the specified \var{fillchar} (default is a
+space).  The original string is returned if
 \var{width} is less than \code{len(\var{s})}.
 \end{methoddesc}
 
@@ -683,9 +684,10 @@ \subsubsection{String Methods \label{string-methods}}
 substring \var{sub} is not found.
 \end{methoddesc}
 
-\begin{methoddesc}[string]{rjust}{width}
+\begin{methoddesc}[string]{rjust}{width\optional{, fillchar}}
 Return the string right justified in a string of length \var{width}.
-Padding is done using spaces.  The original string is returned if
+Padding is done using the specified \var{fillchar} (default is a space).
+The original string is returned if
 \var{width} is less than \code{len(\var{s})}.
 \end{methoddesc}
 
diff --git a/Lib/UserString.py b/Lib/UserString.py
@@ -60,7 +60,8 @@ def __mod__(self, args):
 
     # the following methods are defined in alphabetical order:
     def capitalize(self): return self.__class__(self.data.capitalize())
-    def center(self, width): return self.__class__(self.data.center(width))
+    def center(self, width, *args):
+        return self.__class__(self.data.center(width, *args))
     def count(self, sub, start=0, end=sys.maxint):
         return self.data.count(sub, start, end)
     def decode(self, encoding=None, errors=None): # XXX improve this?
@@ -97,7 +98,8 @@ def isspace(self): return self.data.isspace()
     def istitle(self): return self.data.istitle()
     def isupper(self): return self.data.isupper()
     def join(self, seq): return self.data.join(seq)
-    def ljust(self, width): return self.__class__(self.data.ljust(width))
+    def ljust(self, width, *args):
+        return self.__class__(self.data.ljust(width, *args))
     def lower(self): return self.__class__(self.data.lower())
     def lstrip(self, chars=None): return self.__class__(self.data.lstrip(chars))
     def replace(self, old, new, maxsplit=-1):
@@ -106,7 +108,8 @@ def rfind(self, sub, start=0, end=sys.maxint):
         return self.data.rfind(sub, start, end)
     def rindex(self, sub, start=0, end=sys.maxint):
         return self.data.rindex(sub, start, end)
-    def rjust(self, width): return self.__class__(self.data.rjust(width))
+    def rjust(self, width, *args):
+        return self.__class__(self.data.rjust(width, *args))
     def rstrip(self, chars=None): return self.__class__(self.data.rstrip(chars))
     def split(self, sep=None, maxsplit=-1):
         return self.data.split(sep, maxsplit)
diff --git a/Lib/string.py b/Lib/string.py
@@ -237,37 +237,37 @@ def atol(s, base=10):
 
 
 # Left-justify a string
-def ljust(s, width):
-    """ljust(s, width) -> string
+def ljust(s, width, *args):
+    """ljust(s, width[, fillchar]) -> string
 
     Return a left-justified version of s, in a field of the
     specified width, padded with spaces as needed.  The string is
-    never truncated.
+    never truncated.  If specified the fillchar is used instead of spaces.
 
     """
-    return s.ljust(width)
+    return s.ljust(width, *args)
 
 # Right-justify a string
-def rjust(s, width):
-    """rjust(s, width) -> string
+def rjust(s, width, *args):
+    """rjust(s, width[, fillchar]) -> string
 
     Return a right-justified version of s, in a field of the
     specified width, padded with spaces as needed.  The string is
-    never truncated.
+    never truncated.  If specified the fillchar is used instead of spaces.
 
     """
-    return s.rjust(width)
+    return s.rjust(width, *args)
 
 # Center a string
-def center(s, width):
-    """center(s, width) -> string
+def center(s, width, *args):
+    """center(s, width[, fillchar]) -> string
 
     Return a center version of s, in a field of the specified
     width. padded with spaces as needed.  The string is never
-    truncated.
+    truncated.  If specified the fillchar is used instead of spaces.
 
     """
-    return s.center(width)
+    return s.center(width, *args)
 
 # Zero-fill a number, e.g., (12, 3) --> '012' and (-3, 3) --> '-03'
 # Decadent feature: the argument may be a string or a number
diff --git a/Lib/test/string_tests.py b/Lib/test/string_tests.py
@@ -227,23 +227,23 @@ def test_ljust(self):
         self.checkequal('abc   ', 'abc', 'ljust', 6)
         self.checkequal('abc', 'abc', 'ljust', 3)
         self.checkequal('abc', 'abc', 'ljust', 2)
-
+        self.checkequal('abc*******', 'abc', 'ljust', 10, '*')
         self.checkraises(TypeError, 'abc', 'ljust')
 
     def test_rjust(self):
         self.checkequal('       abc', 'abc', 'rjust', 10)
         self.checkequal('   abc', 'abc', 'rjust', 6)
         self.checkequal('abc', 'abc', 'rjust', 3)
         self.checkequal('abc', 'abc', 'rjust', 2)
-
+        self.checkequal('*******abc', 'abc', 'rjust', 10, '*')
         self.checkraises(TypeError, 'abc', 'rjust')
 
     def test_center(self):
         self.checkequal('   abc    ', 'abc', 'center', 10)
         self.checkequal(' abc  ', 'abc', 'center', 6)
         self.checkequal('abc', 'abc', 'center', 3)
         self.checkequal('abc', 'abc', 'center', 2)
-
+        self.checkequal('***abc****', 'abc', 'center', 10, '*')
         self.checkraises(TypeError, 'abc', 'center')
 
     def test_swapcase(self):
diff --git a/Misc/NEWS b/Misc/NEWS
@@ -12,6 +12,10 @@ What's New in Python 2.4 alpha 1?
 Core and builtins
 -----------------
 
+- For str and unicode objects, the ljust(), center(), and rjust()
+  methods now accept an optional argument specifying a fill
+  character other than a space.
+
 - When method objects have an attribute that can be satisfied either
   by the function object or by the method object, the function
   object's attribute usually wins.  Christian Tismer pointed out that
diff --git a/Objects/stringobject.c b/Objects/stringobject.c
@@ -2617,62 +2617,67 @@ pad(PyStringObject *self, int left, int right, char fill)
 }
 
 PyDoc_STRVAR(ljust__doc__,
-"S.ljust(width) -> string\n"
+"S.ljust(width[, fillchar]) -> string\n"
 "\n"
 "Return S left justified in a string of length width. Padding is\n"
-"done using spaces.");
+"done using the specified fill character (default is a space).");
 
 static PyObject *
 string_ljust(PyStringObject *self, PyObject *args)
 {
     int width;
-    if (!PyArg_ParseTuple(args, "i:ljust", &width))
+    char fillchar = ' ';
+
+    if (!PyArg_ParseTuple(args, "i|c:ljust", &width, &fillchar))
         return NULL;
 
     if (PyString_GET_SIZE(self) >= width && PyString_CheckExact(self)) {
         Py_INCREF(self);
         return (PyObject*) self;
     }
 
-    return pad(self, 0, width - PyString_GET_SIZE(self), ' ');
+    return pad(self, 0, width - PyString_GET_SIZE(self), fillchar);
 }
 
 
 PyDoc_STRVAR(rjust__doc__,
-"S.rjust(width) -> string\n"
+"S.rjust(width[, fillchar]) -> string\n"
 "\n"
 "Return S right justified in a string of length width. Padding is\n"
-"done using spaces.");
+"done using the specified fill character (default is a space)");
 
 static PyObject *
 string_rjust(PyStringObject *self, PyObject *args)
 {
     int width;
-    if (!PyArg_ParseTuple(args, "i:rjust", &width))
+    char fillchar = ' ';
+
+    if (!PyArg_ParseTuple(args, "i|c:rjust", &width, &fillchar))
         return NULL;
 
     if (PyString_GET_SIZE(self) >= width && PyString_CheckExact(self)) {
         Py_INCREF(self);
         return (PyObject*) self;
     }
 
-    return pad(self, width - PyString_GET_SIZE(self), 0, ' ');
+    return pad(self, width - PyString_GET_SIZE(self), 0, fillchar);
 }
 
 
 PyDoc_STRVAR(center__doc__,
-"S.center(width) -> string\n"
+"S.center(width[, fillchar]) -> string\n"
 "\n"
-"Return S centered in a string of length width. Padding is done\n"
-"using spaces.");
+"Return S centered in a string of length width. Padding is\n"
+"done using the specified fill character (default is a space)");
 
 static PyObject *
 string_center(PyStringObject *self, PyObject *args)
 {
     int marg, left;
     int width;
+    char fillchar = ' ';
 
-    if (!PyArg_ParseTuple(args, "i:center", &width))
+    if (!PyArg_ParseTuple(args, "i|c:center", &width, &fillchar))
         return NULL;
 
     if (PyString_GET_SIZE(self) >= width && PyString_CheckExact(self)) {
@@ -2683,7 +2688,7 @@ string_center(PyStringObject *self, PyObject *args)
     marg = width - PyString_GET_SIZE(self);
     left = marg / 2 + (marg & width & 1);
 
-    return pad(self, left, marg - left, ' ');
+    return pad(self, left, marg - left, fillchar);
 }
 
 PyDoc_STRVAR(zfill__doc__,
diff --git a/Objects/unicodeobject.c b/Objects/unicodeobject.c
@@ -4404,19 +4404,47 @@ unicode_capwords(PyUnicodeObject *self)
 }
 #endif
 
+/* Argument converter.  Coerces to a single unicode character */
+
+static int
+convert_uc(PyObject *obj, void *addr)
+{
+	Py_UNICODE *fillcharloc = (Py_UNICODE *)addr;
+	PyObject *uniobj;
+	Py_UNICODE *unistr;
+
+	uniobj = PyUnicode_FromObject(obj);
+	if (uniobj == NULL) {
+		PyErr_SetString(PyExc_TypeError,
+			"The fill character cannot be converted to Unicode");
+		return 0;
+	}
+	if (PyUnicode_GET_SIZE(uniobj) != 1) {
+		PyErr_SetString(PyExc_TypeError,
+			"The fill character must be exactly one character long");
+		Py_DECREF(uniobj);
+		return 0;
+	}
+	unistr = PyUnicode_AS_UNICODE(uniobj);
+	*fillcharloc = unistr[0];
+	Py_DECREF(uniobj);
+	return 1;
+}
+
 PyDoc_STRVAR(center__doc__,
-"S.center(width) -> unicode\n\
+"S.center(width[, fillchar]) -> unicode\n\
 \n\
-Return S centered in a Unicode string of length width. Padding is done\n\
-using spaces.");
+Return S centered in a Unicode string of length width. Padding is\n\
+done using the specified fill character (default is a space)");
 
 static PyObject *
 unicode_center(PyUnicodeObject *self, PyObject *args)
 {
     int marg, left;
     int width;
+    Py_UNICODE fillchar = ' ';
 
-    if (!PyArg_ParseTuple(args, "i:center", &width))
+    if (!PyArg_ParseTuple(args, "i|O&:center", &width, convert_uc, &fillchar))
         return NULL;
 
     if (self->length >= width && PyUnicode_CheckExact(self)) {
@@ -4427,7 +4455,7 @@ unicode_center(PyUnicodeObject *self, PyObject *args)
     marg = width - self->length;
     left = marg / 2 + (marg & width & 1);
 
-    return (PyObject*) pad(self, left, marg - left, ' ');
+    return (PyObject*) pad(self, left, marg - left, fillchar);
 }
 
 #if 0
@@ -5170,24 +5198,26 @@ unicode_length(PyUnicodeObject *self)
 }
 
 PyDoc_STRVAR(ljust__doc__,
-"S.ljust(width) -> unicode\n\
+"S.ljust(width[, fillchar]) -> unicode\n\
 \n\
 Return S left justified in a Unicode string of length width. Padding is\n\
-done using spaces.");
+done using the specified fill character (default is a space).");
 
 static PyObject *
 unicode_ljust(PyUnicodeObject *self, PyObject *args)
 {
     int width;
-    if (!PyArg_ParseTuple(args, "i:ljust", &width))
+    Py_UNICODE fillchar = ' ';
+
+    if (!PyArg_ParseTuple(args, "i|O&:ljust", &width, convert_uc, &fillchar))
         return NULL;
 
     if (self->length >= width && PyUnicode_CheckExact(self)) {
         Py_INCREF(self);
         return (PyObject*) self;
     }
 
-    return (PyObject*) pad(self, 0, width - self->length, ' ');
+    return (PyObject*) pad(self, 0, width - self->length, fillchar);
 }
 
 PyDoc_STRVAR(lower__doc__,
@@ -5552,24 +5582,26 @@ unicode_rindex(PyUnicodeObject *self, PyObject *args)
 }
 
 PyDoc_STRVAR(rjust__doc__,
-"S.rjust(width) -> unicode\n\
+"S.rjust(width[, fillchar]) -> unicode\n\
 \n\
 Return S right justified in a Unicode string of length width. Padding is\n\
-done using spaces.");
+done using the specified fill character (default is a space).");
 
 static PyObject *
 unicode_rjust(PyUnicodeObject *self, PyObject *args)
 {
     int width;
-    if (!PyArg_ParseTuple(args, "i:rjust", &width))
+    Py_UNICODE fillchar = ' ';
+
+    if (!PyArg_ParseTuple(args, "i|O&:rjust", &width, convert_uc, &fillchar))
         return NULL;
 
     if (self->length >= width && PyUnicode_CheckExact(self)) {
         Py_INCREF(self);
         return (PyObject*) self;
     }
 
-    return (PyObject*) pad(self, width - self->length, 0, ' ');
+    return (PyObject*) pad(self, width - self->length, 0, fillchar);
 }
 
 static PyObject*
