# HG changeset patch
# User nishanth
# Date 1284713932 -19800
# Node ID 234b393cbc85a9e16927b278c80f66976291a98a
# Parent  e75538bca17804756776f1934e95a8697e69eb74
initial commit tuples

diff -r e75538bca178 -r 234b393cbc85 tuples.rst
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/tuples.rst	Fri Sep 17 14:28:52 2010 +0530
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+Hello friends and welcome to the tutorial on Tuples
+
+{{{ Show the slide containing title }}}
+
+{{{ Show the slide containing the outline slide }}}
+
+In this tutorial, we shall learn
+
+ * what are tuples
+ * their similarities and dissimilarities with lists
+ * why are they needed
+
+Let`s get started by defining a tuple. A tuple is defined by enclosing
+parantheses around a sequence of items seperated by commas. It is similar to
+defining a list except that parantheses are used instead of square brackets.
+::
+
+    t = (1, 2.5, "hello", -4, "world", 1.24, 5)
+    t
+
+defines a tuple. The items in the tuple are indexed using numbers and can be 
+accessed by using their position.
+::
+
+    t[3]
+
+prints -4 which is the fourth item of the tuple.
+
+::
+
+    t[1:5:2]
+
+prints the corresponding slice
+
+This is the behaviour similar as to lists. But the difference can be seen when
+we try to change an element in the tuple.
+::
+
+    t[2] = "Hello"
+
+We can see that, it raises an error saying tuple does not support item
+assignment. It only implies that tuples are immutable or in simple words,
+tuples cannot be changed.
+
+But what is the use of tuples!!!
+
+We shall understand that soon. But let us look at a simple problem of swapping
+values.
+
+{{{ Pause here and try out the following exercises }}}
+
+%% 1 %% a = 5 and b = 7. swap the values of a and b
+
+{{{ continue from paused state }}}
+::
+
+    a = 5
+    b = 7
+
+    a
+    b
+
+We define the two values
+::
+    temp = a
+    a = b
+    b = temp
+
+    a
+    b
+
+This is the traditional approach
+
+Now let us do it the python way
+::
+
+    a
+    b
+
+    a, b = b, a
+
+    a
+    b
+
+We see that the values are swapped.
+This idiom works for different datatypes also.
+::
+
+    a = 2.5
+    b = "hello"
+
+    a
+    b
+
+Moreover this type of behaviour is straight forward and what you would expect
+should happen naturally.
+
+This is possible because of the immutability of tuples. This process is called
+tuple packing and unpacking.
+
+Let us first see what is tuple packing. Type
+::
+
+    5,
+
+What we see is a tuple with one element.
+::
+
+    5, "hello", 2.5
+
+Now it is a tuple with two elements.
+
+So when we are actually typing two or more elements seperated by commas, those
+elements are packed and a tuple is made from them.
+
+When you type
+::
+
+    a, b = b, a
+
+First the values of b and a are packed into a tuple on the right side and then
+unpacked into the variables a and b.
+
+Immutability of tuples ensures that the values are not changed during the
+packing and unpacking.
+
+{{{ Show summary slide }}}
+
+This brings us to the end of the tutorial.
+we have learnt
+
+ * How to define tuples
+ * The similarities of tuples with lists, like indexing and iterability
+ * The immutability of tuples
+ * The value swapping idiom in Python
+ * packing and unpacking of tuples
+
+{{{ Show the "sponsored by FOSSEE" slide }}}
+
+#[Nishanth]: Will add this line after all of us fix on one.
+This tutorial was created as a part of FOSSEE project, NME ICT, MHRD India
+
+Hope you have enjoyed and found it useful.
+Thankyou
+ 
+.. Author              : Nishanth
+   Internal Reviewer 1 : 
+   Internal Reviewer 2 : 
+   External Reviewer   :