Beginning Programming with Python for Dummies, 3rd Edition – Page 2

In Praise of Dual Monitors

This is an update of a post that originally appeared on February 5, 2014.

In reading many of my old blog posts, I’m finding that many of the things I said way back when apply equally well today. I’ve received email from budding developers who use their smartphone to code. Just how they perform this trick is beyond me because I squint at the screen performing the simplest of tasks and often find that my fingers are two sizes too big. I have tried coding on a tablet, a laptop, and (oddly enough) my television. While they do work, they’re not particularly efficient, so I’ll stick with my dual-monitor desktop system for coding.

Yes, I know that some developers use more than just two monitors, but I find that two monitors work just fine. The first monitor is my work monitor—the monitor I use for actually typing code. The second monitor is my view monitor. When I run the application, the output appears on the second monitor so that I can see the result of changes I’ve made. Using two monitors lets me easily correlate the change in code to the changes in application design. Otherwise, I’d be wasting time switching between the application output and my IDE.

I also use two monitors when writing my books. The work monitor contains my word processor, while my view monitor contains the application I’m writing about. This is possibly one time when a third monitor could be helpful—one to hold the word processor, one to hold the IDE, and one to view the application output. However, in this case, a third monitor could actually slow things down because the time spent viewing the output of an example is small when compared to creating a production application.

The concept of separating work from the source of information used to perform the work isn’t new. People have used the idea for thousands of years, in fact. For example, when people employed typewriters to output printed text, the typist employed a special stand to hold the manuscript being typed. The idea of having a view of your work and then another surface to actually work on is used quite often throughout history because it’s a convenient way to perform tasks quickly. By employing dual monitors, I commonly get between a 15 percent to 33 percent increase in output, simply because I can see my work and its associated view at the same time.

Working with dual monitors not only saves time, but can also reduce errors. By typing as I view the output of applications, I can more reliably relate the text of labels and other information the application provides. The same holds true when viewing information sources found in other locations. Seeing the information as I type it is always less likely to produce errors.

Don’t get the idea that I support using dual monitors in every situation. Many consumer-oriented computer uses are served just fine with a single monitor. For example, there isn’t a good reason to use two monitors when viewing e-mail in many cases—at least, not at the consumer level (you could make a case for using dual monitors when working with e-mails and a calendar to manage tasks, for example). Dual monitors commonly see use in the business environment because people aren’t necessarily creating their own information source—the information comes from a variety of sources that the user must view in order to use reliably.

Do you see yourself using dual monitors? If you use such a setup now, how do you employ it? Let me know at [email protected].

Choosing Variable Names

This is an update of a post that originally appeared on January 17, 2014.

It often surprises me that developers seem to choose completely useless variable names like MyVariable when creating an application. Although MyVariable could be an interesting variable name for an example in a book, it never has a place in any sort of production code. Even then, I try to create book examples with meaningful variable names, especially when getting past the initial “Hello World” example. Variable names are important because they tell others:

What sort of information the variable stores
When the variable is commonly used
Where the variable is used
How to use the variable correctly
Why the variable is important

In some cases, the variable name could even indicate who created the variable; although, this sort of information is extremely rare. If you never thought a variable name should contain all that information, then perhaps you haven’t been choosing the best variable names for your application.

Even with these restrictions in place, choosing a variable name can be uncommonly hard if you want to maximize the name’s value to both yourself and other developers. Some organizations make the selection process easier by following certain conventions. If you don’t have an organizational style guide for variable naming, modern programming languages like Python commonly provide a style guide for you to use. These style guides often consider a great deal more than simply variable naming and include issues like the amount of indentation to use. In some respects, they become quite draconian in their approach. Other style guides, like the one for C#, are less time consuming to learn, which is a good thing because most developers have better things to do with their time than to learn some of these nitpicky details. A few languages suffer from an abundance of style guides, like C++. It’s best to choose one of them, such as the Google C++ Style Guide, and stick with it.

However, let’s say that you want to create your own style guide for your organization to use because you use multiple languages and having a different style guide for each language seems just a bit absurd, not to mention adding needless complexity. In this case, you need to ask yourself a series of questions to determine how you want the style guide to work, such as these:

What sort of casing do you want to use for what types of variables?
What information does the variable contain (such as a list of names)?
How is the variable used (such as locally or globally, or to contain coordinates, or a special kind of object)?
When appropriate, what kind of information does the variable contain (such as a string or the coordinate of a pixel on screen)?
Is the variable used for a special task (such as data conversion)?
What case should prefixes, suffixes, and other naming elements appear in when a language is case sensitive?

The point is that you need to choose variable names with care so that you know what they mean later. Carefully chosen variable names make it possible for you to read your code with greater ease and locate bugs a lot faster. They also make it easier for others to understand your code and for you to remember what the code does months after you’ve written it. However, most important of all, useful variable names help you see immediately that a variable is being using the wrong way, such as assigning the length of a name string to a coordinate position on screen (even though both variables are integer values). Let me know your thoughts about variable naming at [email protected].

Sending Comments on My Books

This is an update of a post that originally appeared on February 23, 2012.

I regularly receive a stack of e-mail about my books. Readers question everything and it makes me happy to see that they’re reviewing my books so closely. It means that I’m accomplishing my principle goal, helping you understand computers in every possible way so that you can be more productive and accomplish tasks with less effort. When I make something easier for someone and they tell me about it, the grin extends from one side of my face to another. It really makes my day.

Some readers are still asking me if it’s OK to send me comments. I definitely want to see any constructive comment that you have. Anything that helps me understand your needs better makes it possible for me to write better books. I really do want to hear from you. The main element that I need to obtain a usable comment is that it’s constructive. A comment that lacks details isn’t helpful because I’ve written so many books. Emotional comments without any substance are especially hard to deal with because they leave me wondering what you need from me. Here are some of the things you can do to create a constructive comment:

What is the title of the book you’re reading (be sure to include the edition number, which is usually right on the cover unless it’s a first edition)?
Are you using the downloadable source code if this is a programming book?
Did you install the recommended version of any required software using the instructions found in the book?
Which page contains the error (if you’re using Kindle or other electronic media, please provide a chapter number and section title as a minimum)?
What do you view as an error on that page?
How would you fix the error?
What sort of system are you running?
When did you encounter the problem?

The more information you provide, the easier it is for me to understand the issue and provide you with feedback. In many cases, I’ll upload the fix to my blog so that everyone can benefit from the response (so be sure you keep an eye on my blog for new entries). I work hard to ensure that my books are as error free as possible, but everyone makes mistakes. Also remember that sometimes mitigating factors, such as differences in software versions or anticipated hardware, make it appear that there is an error in the book when you’re really looking at a different in environment. Help me provide you with better books—send me comments!

There are a few things that I won’t do for you. I won’t help you pass an exam at school. Your learning experience is important to me, which means that I want you to continue your education by working through the instruction on your own. I also don’t provide free consulting. This means I won’t check the code that you created on your own for errors. In addition, if you don’t use the downloadable source, be sure to read Verifying Your Hand Typed Code for restrictions on the level of support that I provide. I’ll help you with any book-specific question, but I draw the line at that point. Let me know if you have any input or insights on my books at [email protected].

Book Reviews – Doing Your Part

This is an update of a post that originally appeared on October 4, 2013.

Readers contact me quite a lot about my books. On an average day, I receive around 65 reader e-mails about a wide range of book-related topics. Many of them are complimentary about my books and it’s hard to put down in words just how much I appreciate the positive feedback. Often, I’m humbled to think that people would take time to write.

There is another part to reader participation in books, however, and it doesn’t have anything to do with me—it has to do with other readers. When you read one of my books and find the information useful, it’s helpful to write a review about it so that others can know what to expect. I want to be sure that every reader who purchases one of my books is happy with that purchase and gets the most possible out of the book. The wording that the publisher’s marketing staff and I use to describe a book represents our viewpoint of that book and not necessarily the viewpoint of the reader. The only way that other readers will know how a book presents information from the reader perspective is for other readers to write reviews. A good review will tell:

What you liked about the book
How it met your needs
What it provides in the way of usable content
Whether you liked any intangibles, such as the author’s writing style
When you used the content to obtain a new job or learn a new skill
Who recommended the book to you

The review should also present any negatives (obviously, I want to know about the flaws, too, so that I can correct them in the next edition of the book and also discuss them on my blog):

Did the book provide enough detailed procedures needed to accomplish a task?
Are significant technical flaws and why do you feel they’re an issue?
Are there enough graphics to augment the text and make it clearer?
Is the source code useful?

Many reviewing venues, such as the one found on Amazon, also ask you to provide a rating for the book. You should rate the book based on your experience with other books and on how this particular book met your needs in learning a new topic. The kind of review to avoid writing is a rant or one that isn’t actually based on reading the whole book. As always, I’m here (at [email protected]) to answer any questions you have and many of your questions have appeared as blog posts when the situation warrants.

So, just where do you make these reviews? The publishers sometimes provide a venue for expressing your opinion and you can certainly go to the publisher site to create such a review. I personally prefer to upload my reviews to Amazon because it’s a location that many people frequent to find out more about books. You can go to the site, click Write a Customer Review (near the bottom of the page), and then provide your viewpoint about the book.

Thank you in advance for taking the time and effort required to write a review. I know it’s time consuming, but it’s an important task that only you can perform.

Using the Set Command to Your Advantage

This is an update of a post that originally appeared on February 24, 2014.

A short while ago, I created a post about the Windows path. A number of people wrote me about that post with questions. Yes, you can use the technique for setting the Path environment variable to set any other environment variable. The Windows Environment Variables dialog box works for any environment variable—including those used by language environments such as Java, JavaScript, and Python. Windows doesn’t actually care what sort of environment variable you create using the method that I discuss in that post. The environment variable will appear in every new command prompt window you create for either a single user or all users of a particular system, depending on how you create the environment variable.

A few of you took me to task for not mentioning the Set command. This particular command appears in Microsoft Windows Command Line Administration Instant Reference. It’s a useful command because you can temporarily configure a command prompt session to support a new set of settings. When the session is ended, the settings are gone. Only those settings you create as part of Environment Variables window have any permanence. There are other tricks you can use, but using Set for temporary environment variables and the Environment Variables window for permanent environment variables are the two most common approaches.

In order to see the current environment variables you simply type Set and press Enter at the command line. If you add a space and one or more letters, you see just the matching environment variables. For example, type Set U and press Enter to see all of the environment variables that begin with the letter U.

To set an environment variable, you add the name of the variable, an equals sign (=), and the variable value. For example, to set the value of MyVariable to Hello, you type Set MyVariable=Hello and press Enter. To verify that MyVariable does indeed equal Hello, you type Set MyVariable and press Enter. The command prompt will display the value of MyVariable. When you’re done using MyVariable, you can type Set MyVariable= and press Enter. Notice the addition of the equals sign. If you ask for the value of MyVariable again, the command prompt will tell you it doesn’t exist.

Newer versions of the command prompt provide some additional functionality. For example, you might set MyVariable within a batch file and not know what value it should contain when you create the batch file. In this case, you can prompt the user to provide a value using the /P command line switch. For example, if you type Set /P MyVariable=Type a value for my variable: and press Enter, you’ll see a prompt to enter the variable value.

It’s also possible to perform math with Set using the /A command line switch. There is a whole list of standard math notations you can use. Type Set /? and press Enter to see them all. If you write application code at all, you’ll recognize the standard symbols. For example, if you want to increment the value of a variable each time something happens, you can use the += operator. Type Set /A MyVariable+=1 and press Enter to see how this works. The first time you make the call, MyVariable will equal 1. However, on each succeeding call, the value will increment by 1 (for values of 2, 3, and so on).

Environment variables support expansion and you can see this work using the Echo command. For example, if you type Echo %MyVariable%, you see the value of MyVariable.

However, you might not want the entire value of MyVariable. Newer versions of the command prompt support substrings. The variable name is followed by a :~, the beginning position, a comma, and the ending position. For example, if you place Hello World in MyVariable, and then type Echo %MyVariable:~0,5% and press Enter, you see Hello as the output, not Hello World. Adding a negative sign causes the expansion to occur from the end of the string. For example, if you type Echo %MyVariable:~-5% and press Enter, you see World as the output.

The Set command is a valuable addition to both the administrator’s and programmer’s toolkit because it lets you set environment variables temporarily. The Set command figures prominently in batch file processing and also provides configuration options for specific needs. Let me know about your environment variable questions as they pertain to my books at [email protected].

Python Used for Common User Interface Needs

This is an update of a post that originally appeared on September 12, 2014.

Beginning Programming with Python For Dummies, 3rd Edition describes how to start working with Python. You discover how to perform all the basics and I provide a few real world examples. However, once you’re done with the book, you might ask how Python can be used for real world programming of the sort that you need to do. One of the most common tasks is creating a user interface. Just about every application out there requires a user interface and it has become popular to make user interfaces touchable. Fortunately, Python developers have access to a huge number of libraries to make seemingly hard tasks simple. In fact, that’s one of the advantages of using Python—the immense number of really practical and useful libraries at your disposal. It’s possible to find a library for just about any need.

One of the more interesting libraries available for Python is Kivy. This library makes it possible to create multitouch applications without having to do all the heavy lifting yourself. The interesting thing about using Kivy for this task is that it helps you avoid some of the problems with other sort of multitouch application environments, such as using a combination of HTML5, CSS3, and JavaScript (where a less than compatible browser can ruin your chances of making the application work properly). This is a native code library that works on the Linux, Windows, OS X, Android and iOS platforms, so you have a good chance of finding precisely the support you need in a package that will perform well on the chosen platforms. Like all Python applications, the application you create on the Mac will work just fine on Windows too.

Of course, there are tons of libraries for Python, so why did I choose to talk about this particular library? It turns out that Kivy is proactive about obtaining as much developer support as possible. I’ll admit it, I was bedazzled looking at all the eye candy on this site. What I thought was a five minute scan of the example applications turned out to be more than an hour of perusing what’s possible with Kivy and Python. All you need to do to try one of the applications out is to click its link, download the code, and start running it. Nothing could be easier (or time consuming as it turns out). Soon, you’ll find your days consumed by checking out Kivy applications too.

Fortunately, Kivy is also free. All you need to do is download the copy for your platform and install it. So, you get this great library that you can use for your business applications and it doesn’t cost you a dime. What I’d most like to hear about is whether someone is using Kivy in a large scale business application and how its performing for them. Speed is always an issue with Python, despite all the other amazing features it provides, so finding libraries that use every bit of speed Python has to offer is essential.

I take a lot of time looking for various tools, libraries, applications, and other resources for readers to use with my books. I’m not looking for anything cheesy, crippled, or difficult to use—I want well written, popular, and preferably free resources I can share. If you are a developer who is using an outstanding library or tool that specifically meets the needs of my readers, please let me know about it at [email protected]. Please, no vendors! I want to hear from people not associated with an organization who are actually using the tool or library in question for development purposes.

Python Community Support

This is an update of a post that originally appeared on October 13, 2014.

There are many issues to consider when choosing a programming language. Python is no exception. Just because I feel it’s the right tool to meet some of my needs doesn’t mean it will work well for you. That’s why the Understanding Why Python is So Cool section of Chapter 1 in Beginning Programming with Python For Dummies, 3rd Edition is so important. This section tells you why I see Python as an important programming language and why you might want to use it too. I break the problem into three parts: what Python can do for your application needs, how Python can benefit you personally, and which organizations are using Python for specific tasks. Between the three sections, you can make an intelligent decision as to whether Python will actually serve your particular needs. I really don’t want you to take my word for it—I would rather know that you selected Python based on your own research.

No matter how interesting a language is, no matter how many features it provides, and no matter how much you personally like it—you can’t typically learn a language that lacks broad community support with any ease. If no one else is using the language and contributing to it in some major way, the language will eventually die. Fortunately, Python doesn’t have this problem. Chapter 21 of my book discusses ten essential libraries for Python, none of which come with the language when you download it. In fact, the introduction to this chapter lists a number of places where you can find even more libraries to use.

The thing is that Python keeps attracting ever more attention. A recent Dev article, 10 Best Tools Python Programmers Can Learn in 2023, provides you with access to tools you really need to know about. The point about tools is that they represent an essential form of community support. As people use a language, they start to build places where others can discuss it with them. However, that’s only one form of community support. Tools represent a significant increase in support because creating, debugging, and supporting a tool requires time and effort that most developers don’t have in abundance. Someone really has to believe in a language to provide this sort of language support.

The fact is that Python has become a “must learn” language. It has great community support, provides a broad range of functionality through libraries and tools, and is fully supported by the academic community. Even though other languages have had these advantages and eventually failed, the chances are far less likely that Python will experience problems. In fact, many rankings sites show Python as being the most popular language out there right now.

Community support is an essential determinant of programming language popularity. How do you rank Python in your toolbox and why? Let me know at [email protected]. Tell me about your favorite Python library or tool and how you use it as well. (No vendor emails please, I want to hear from developers who are actually using products.) I’m interested in discovering just what makes some languages so incredibly popular (Python being one of the most popular).

Adding a Location to the Windows Path

This is an update of a post that originally appeared on February 17, 2014.

A number of my books tell the reader to perform tasks at the command line. What this means is that the reader must have access to applications stored on the hard drive. Windows doesn’t track the location of every application. Instead, it relies on the Path environment variable to provide the potential locations of applications. If the application the reader needs doesn’t appear on the path, Windows won’t be able to find it. Windows will simply display an error message. So, it’s important that any applications you need to access for my books appear on the path if you need to access them from the command line.

You can always see the current path by typing Path at the command line and pressing Enter. What you’ll see is a listing of locations, each of which is separated by a semicolon as shown here (your path will differ from mine).

Using the Path command displays the current path.

In this case, Windows will begin looking for an application in the current folder. If it doesn’t find the application there, then it will look in C:\Python33\, then in C:\Program Files (x86)\NVIDIA Corporation\PhysX\Common, and so on down the list. Each potential location is separated from other locations using a semicolon as shown in the figure.

There are a number of ways to add a location to the Windows path. If you only need to add a path temporarily, you can simply extend the path by setting it to the new value, plus the old value. For example, if you want to add C:\MyApp to the path, you’d type Path=C:\MyApp;%Path% and press Enter. Notice that you must add a semicolon after C:\MyApp. Using %Path% appends the existing path after C:\MyApp. Here is how the result looks on screen.

Adding a path is a relatively simple process using the Path= command

Of course, there are times when you want to make the addition to the path permanent because you plan to access the associated application regularly. In this case, you must perform the task within Windows itself. The following steps tell you how.

1. Right click This Computer (or Computer) and choose Properties from the context menu or select Settings (or System in the Control Panel). You see the a Settings (System) window similar to the one shown here open (precisely what you see depends on which version of Windows you have, the figure shows Windows 10).

2. Click Advanced System Settings. You see the Advanced tab of the System Properties dialog box shown here.

The Advanced tab provides access to your permanent path in Windows.

3. Click Environment Variables. You see the Environment Variables dialog box shown here. Notice that there are actually two sets of variables. The top set affects only the current user. So, if you plan to use the application, but don’t plan for others to use it, you’d make the Path environment variable change in the top field. The bottom set affects everyone who uses the computer. This is where you’d change the path if you want everyone to be able to use the application.

There are paths that affect only the current user and those that affect the system as a whole.

4. Locate the existing Path environment variable in the list of variables for either the personal or system environment variables and click Edit. If there is no existing Path environment variable, click New instead. You see a dialog box similar to the one shown here when working with Windows 10 (other versions of Windows will show a different dialog box, but the purpose is the same, to edit the path).

Each path location appears on a separate line to make it easy to edit.

When you open a new command prompt, you’ll see the new path in play. Changing the environment variable won’t change the path for any existing command prompt windows. Having the right path available when you want to perform the exercises in my books is important. Let me know if you have any questions about them at [email protected].

Antiquated Technology Making Developers Faster

This is an update of a post that originally appeared on November 7, 2014.

I often wonder when I create a blog post whether the technology I’m describing will stand the test of time. In this case, I asked whether the reader would like to be able to type application code faster and with fewer keystrokes. The article, The 100 Year Old Trick to Writing at 240 Words Per Minute, probably has some good advice for you—at least, if you’re willing to learn the technique. It turns out that stenography isn’t only useful for court typists and people who print out the text for the hearing impaired on television, it’s also quite useful for developer. Yes, your IDE probably has more than a few tricks available for speeding up your typing, but I guarantee that these tricks only go so far. My personal best typing speed is 110 wpm and that’s flat out typing as fast as my fingers will go.

Since that original post, someone has come out with a book called Learn Plover! that describes how to use this stenographic technique in more detail. There is also a site devoted to Plover now.

Naturally, I haven’t ever used one of the devices mentioned in the article. However, a stenographer named Mirabai Knight has tried one of the devices and reproduced a 140 keystroke Python application using only 50 keystrokes. By the way, she has produced a series of interesting videos that you may want to review if you really think that Plover is for you. I don’t know of any IDE that can provide that sort of efficiency. Of course, it’s one thing for a trained stenographer to produce these sorts of results, but I’d like to hear from any developer who has used the technique to hear about how well it worked for them. Please contact me about your experiences at [email protected]. (Oddly enough, I did hear from at least one developer who uses it successfully.)

The part that interested me most though is that the system, called Plover, is written in Python. (If you want to see Plover in action, check out the video at http://plover.stenoknight.com/2014/10/longer-plover-coding-snippet-in-python.html. A number of Beginning Programming with Python For Dummies, 3rd Edition readers have written to ask me how they can use their new found programming skills. The book contains sections that tell you about all sorts of ways in which Python is being used, but many of these uses are in large corporations. This particular use is by a small developer—someone just like you. Yet, it has a big potential for impacting how developers work. Just imagine the look on the boss’ face when you turn in your application in half the time because you can type it in so much faster? So, Python isn’t just for really large companies or for scientists—it’s for everyone who needs a language that can help them create useful applications of the sort that Python is best suited to target (and I describe all of these uses in my book).

Understanding the Continuing Need for C++

This is an update of a post that originally appeared on February 23, 2015.

I maintain statistics on all my books, including C++ All-In-One for Dummies, 4th Edition. These statistics are based on reader e-mail and other sources of input that I get. I even take the comments on Amazon.com into account. One of the most common C++ questions I get (not the most common, but it’s up there) is why someone would want to use the language in the first place. It’s true, C++ isn’t the language to use if you’re creating a database application and schools now prefer Python as an introductory programming language for older children. However, it is the language to use if you’re writing low-level code that has to run fast. C++ also sees use in a vast number of libraries because library code has to be fast. For example, check out the Python libraries at some point and you’ll find C++ staring back at you. In fact, part of the Python documentation discusses how to use C++ to create extensions.

I decided to look through some of my past notes to see if there was some succinct discussion of just why C++ is a useful language for the average developer to know. That’s when I ran across an InfoWorld article entitled, “Stroustrup: Why the 35-year-old C++ still dominates ‘real’ dev.” Given that the guy being interviewed is Bjarne Stroustrup, the inventor of C++, it’s a great source of information. The interview is revealing because it’s obvious that Bjarne is taking a measured view of C++ and not simply telling everyone to use it for every occasion (quite the contrary, in fact).

The bottom line in C++ development is speed. Along with speed, you also get flexibility and great access to the hardware. As with anything, you pay a price for getting these features. In the case of C++, you’ll experience increased development time, greater complexity, and more difficulty in locating bugs. Some people are taking a new route to C++ speed though and that’s to write their code in one language and move it to C++ from there. For example, some Python developers are now cross-compiling their code into C++ to gain a speed advantage. You can read about it in the InfoWorld article entitled, Python to C converter tool.

A lot of readers will close a message to me asking whether there is a single language they can learn to do everything well. Unfortunately, there isn’t any such language and given the nature of computer languages, I doubt there ever will be. Every language has a niche for which it’s indispensable. The smart developer has a toolbox full of languages suited for every job the developer intends to tackle.

Do you find that you really don’t understand how the languages in my books can help you? Let me know your book-specific language questions at [email protected]. It’s always my goal that you understand how the material you’ve learned while reading one of my books will eventually help you in the long run. After all, what’s the point of reading a book that doesn’t help you in some material way? Thanks, as always, for your staunch support of my writing efforts!