0713

Author: mimiron8080

finally.py

@@ -0,0 +1,16 @@
+#!/usr/bin/python
+# Filename: finally.py
+
+import time
+
+try:
+    f = file('poem.txt')
+    while True: # our usual file-reading idiom
+	line = f.readline()
+	if len(line) == 0:
+	    break
+	time.sleep(2)
+	print line,
+finally:
+    f.close()
+    print 'Cleaning up...closed the file'

picking.py

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+#!/usr/bin/python
+# Filename: picking.py
+
+import cPickle as p
+# import pickle as p
+
+shoplistfile = 'shoplist.data'
+# the name of the file where we will store the object
+
+shoplist = ['apple','mango','carrot']
+
+# Write to the file
+f = file(shoplistfile, 'w')
+p.dump(shoplist, f) # dump the object to a file
+f.close()
+
+del shoplist # remove the shoplist
+
+# Read back from the storage
+f = file(shoplistfile)
+storedlist = p.load(f)
+print storedlist

poem.txt

@@ -0,0 +1,4 @@
+Programming is fun
+When the work is done
+if you wanna make your work also fun:
+    	use Python!

raising.py

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+#!/usr/bin/python
+# Filename: raising.py
+
+class ShortInputException(Exception):
+    '''A user-defined exception class.'''
+    def __init__(self, length, atleast):
+	Exception.__init__(self)
+ 	self.length = length
+	self.atleast = atleast
+
+try:
+    s = raw_input('Enter something --> ')
+    if len(s) < 3:
+	raise ShortInputException(len(s), 3)
+    # Other work can continue as usual here
+except EOFError:
+    print '\nWhy did you do an EOF on me?'
+except ShortInputException, x:
+    print 'ShortInputException: The input was of length %d, \
+          was expecting at least %d' % (x.length, x.atleast)
+else:
+    print 'No exception was raised.'

shoplist.data

@@ -0,0 +1,8 @@
+(lp1
+S'apple'
+p2
+aS'mango'
+p3
+aS'carrot'
+p4
+a.

try_except.py

@@ -0,0 +1,15 @@
+#!/usr/bin/python
+# Filename: try_except.py
+
+import sys
+
+try:
+    s = raw_input('Enter something --> ')
+except EOFError:
+    print '\nWhy did you do an EOF on me?'
+    sys.exit() # exit the program
+except:
+    print '\nSome error/exception occurred.'
+    # here, we are not exiting the program
+
+print 'Done'

using_file.py

@@ -0,0 +1,23 @@
+#!/usr/bin/python
+# Filename: using_file.py
+
+poem='''\
+Programming is fun
+When the work is done
+if you wanna make your work also fun:
+    	use Python!
+'''
+
+f = file('poem.txt','w') # open for 'w' writing
+f.write(poem) # write text to file
+f.close() # close the file
+
+f = file('poem.txt')
+# if no mode is specified, 'r'ead mode is assumed by default
+while True:
+	line = f.readline()
+	if len(line) == 0: # Zero length indicates EOF
+	   break
+	print line,
+	# Notice comma to avoid automatic newline added by Python
+f.close() # close the file