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| Figure 2 . Output from the script in Listing 4. |
|---|
C:\jnk\6>echo off
34
76
Press any key to continue . . . |
Then the value 6 is printed by the last statement in the script, which is not part of the group. (Note that the last statement is not indented.)
Now, let's make a change to the script. The script shown in Listing 5 is identical to the one in Listing 4 except that I switched the values of A and B to cause the group of indentedstatements to be bypassed ( B is no longer greater than A ).
| Listing 5 . Another sample script. |
|---|
A = 4
B = 3if B>A:
print(A) # begin groupprint(B)
print(A + B) # end groupA = 6 # not part of above group
print(A)#============================================================
#The output, which is not part of the script, is shown below.6 |
In this case, only one value (6) is printed because the three print statements in the group were bypassed asa group.
The important point here is that the three indented statements in Listing 4 and Listing 5 constitute a group because of their common indentation level .
I personally don't like the idea of using indentation to create grouping. Although it sounds nice in theory, it can be very labor intensive in practice.Once you have written a script, one simple change can often require you to go back and modify the indentation level of almost every statement in the script.
I guess the good news is that this will encourage you to write your script as a series of short, concise independent modules rather than as asingle long rambling script.
I am also concerned about the accessibility or lack thereof that grouping based on indentation level provides for blind and visually impaired students.
Leading whitespace (spaces and tabs) at the beginning of a logical line is used to compute the indentation level of the line. This, in turn, is used todetermine the grouping of statements.
My advice is to avoid the use of tabs altogether. Use spaces instead, and use the same number of spaces for each statement in the group.
However, if you must use tabs, you should go to the Python Language Reference -- 2.1.8. Indentation and make certain that you understand how Python deals with tabs.
Use spaces to cause the indentation level of all statements in a group of statements to be indented to the same level.Statements in a group are either all executed, or all bypassed by the program logic.
I will provide a visualization of the behavior of indentation in the module titled Itse1359-1065-Visualizing Python in this book .
This section contains a variety of miscellaneous information.
Financial : Although the Connexions site makes it possible for you to download a PDF file for thismodule at no charge, and also makes it possible for you to purchase a pre-printed version of the PDF file, you should beaware that some of the HTML elements in this module may not translate well into PDF.
I also want you to know that, I receive no financial compensation from the Connexions website even if you purchase the PDF version of the module.
In the past, unknown individuals have copied my modules from cnx.org, converted them to Kindle books, and placed them for sale on Amazon.com showing me as the author. Ineither receive compensation for those sales nor do I know who does receive compensation. If you purchase such a book, please beaware that it is a copy of a module that is freely available on cnx.org and that it was made and published withoutmy prior knowledge.
Affiliation : I am a professor of Computer Information Technology at Austin Community College in Austin, TX.
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