Conventions Used in This Book

Here is a typical Code sample.

Example 1. Typical Python Example

combo = { } 
1

for i in range(1,7):
    for j in range(1,7):
        roll= i+j
        combo.setdefault( roll, 0 ) 
2

        combo[roll] += 1
for n in range(2,13):
    print "%d %.2f%%" % ( n, combo[n]/36.0 ) 
3

1

This creates a Python dictionary, a map from key to value. If we initialize it with something like the following: combo = dict( [ (n,0) for n in range(2,13) ] ), we don't need the setdefault function call below.

2

This assures that the rolled number exists in the dictionary with a default frequency count of 0.

3

Print each member of the resulting dictionary. Something more obscure like [ (n,combo[n]/36.0) for n in range(2,13)] is certainly possible.

The output from the above program will be shown as follows:

2 0.03%
3 0.06%
4 0.08%
5 0.11%
6 0.14%
7 0.17%
8 0.14%
9 0.11%
10 0.08%
11 0.06%
12 0.03%

Tool completed successfully

We will use the following type styles for references to a specific Class, method function, attribute, which includes both class variables or instance variables.

Tip

There will be design tips, and warnings, in the material for each exercise. These reflect considerations and lessons learned that aren't typically clear to starting OO designers.