Add truncate() method to StringIO objects.
This closes SourceForge bug #115527.
diff --git a/Lib/StringIO.py b/Lib/StringIO.py
index 02eb7c8..334bf85 100644
--- a/Lib/StringIO.py
+++ b/Lib/StringIO.py
@@ -13,6 +13,7 @@
buf = f.read(n) # read up to n bytes
buf = f.readline() # read until end of line ('\n') or EOF
list = f.readlines()# list of f.readline() results until EOF
+f.truncate([size]) # truncate file at to at most size (default: current pos)
f.write(buf) # write at current position
f.writelines(list) # for line in list: f.write(line)
f.getvalue() # return whole file's contents as a string
@@ -28,6 +29,7 @@
- There's a simple test set (see end of this file).
"""
+import errno
import string
class StringIO:
@@ -102,6 +104,17 @@
break
line = self.readline()
return lines
+ def truncate(self, size=None):
+ if self.closed:
+ raise ValueError, "I/O operation on closed file"
+ if size is None:
+ size = self.pos
+ elif size < 0:
+ raise IOError(errno.EINVAL,
+ "Negative size not allowed")
+ elif size < self.pos:
+ self.pos = size
+ self.buf = self.getvalue()[:size]
def write(self, s):
if self.closed:
raise ValueError, "I/O operation on closed file"