1.6 What Are Python's Technical Strengths?

Naturally, this is a developer's question. If you don't already have a programming background, the words in the next few sections may be a bit baffling—don't worry, we'll explain all of these in more detail as we proceed through this book. For de-velopers, though, here is a quick introduction to some of Python's top technical features.

1.6.1 It's Object-Oriented

Python is an object-oriented language, from the ground up. Its class model supports advanced notions such as polymorphism, operator overloading, and multiple inheritance; yet in the context of Python's simple syntax and typing, OOP is remarkably easy to apply. In fact, if you don't understand these terms, you'll find they are much easier to learn with Python than with just about any other OOP language available.

Besides serving as a powerful code structuring and reuse device, Python's OOP nature makes it ideal as a scripting tool for object-oriented systems languages such as C++ and Java. For example, with the appropriate glue code, Python programs can subclass (specialize) classes implemented in C++ or Java. Of equal significance, OOP is an option in Python; you can go far without having to become an object guru all at once.

1.6.2 It's Free

Python is free. Just like other open source software, such as Tcl, Perl, Linux, and Apache, you can get the entire Python system for free on the Internet. There are no restrictions on copying it, embedding it in your systems, or shipping it with your products. In fact, you can even sell Python's source code, if you are so inclined.

But don't get the wrong idea: "free" doesn't mean "unsupported." On the contrary, the Python online community responds to user queries with a speed that most commercial software vendors would do well to notice. Moreover, because Python comes with complete source code, it empowers developers, and creates a large team of implementation experts. Although studying or changing a programming language's implementation isn't everyone's idea of fun, it's comforting to know that it's available as a final resort and ultimate documentation source. You're not dependent on a commercial vendor.

Python development is performed by a community, which largely coordinates its efforts over the Internet. It consists of Python's creator—Guido van Rossum, the officially anointed Benevolent Dictator For Life (BDFL) of Python—plus a cast of thousands. Language changes must both follow a formal enhancement procedure (known as the PEP process), and be scrutinized by the BDFL. Happily, this tends to make Python more conservative with changes than some other languages.

1.6.3 It's Portable

The standard implementation of Python is written in portable ANSI C, and compiles and runs on virtually every major platform in use today. For example, Python programs run today on everything from PDAs to supercomputers. As a partial list, Python is available on Unix systems, Linux, MS-DOS, MS Windows (95, 98, NT, 2000, XP, etc.), Macintosh (classic and OS X), Amiga, AtariST, Be-OS, OS/2, VMS, QNX, Vxworks, PalmOS, PocketPC and CE, Cray supercomputers, IBM mainframes, PDAs running Linux, and more.

Besides the language interpreter itself, the set of standard library modules that ship with Python are also implemented to be as portable across platform boundaries as possible. Further, Python programs are automatically compiled to portable byte code, which runs the same on any platform with a compatible version of Python installed (more on this in the next chapter).

What that means is that Python programs using the core language and standard libraries run the same on Unix, MS Windows, and most other systems with a Python interpreter. Most Python ports also contain platform-specific extensions (e.g., COM support on MS Windows), but the core Python language and libraries work the same everywhere. As mentioned earlier, Python also includes an interface to the Tk GUI toolkit called Tkinter, which allows Python programs to implement full-featured graphical user interfaces that run on all major GUI platforms without program changes.

1.6.4 It's Powerful

From a features perspective, Python is something of a hybrid. Its tool set places it between traditional scripting languages (such as Tcl, Scheme, and Perl), and systems development languages (such as C, C++, and Java). Python provides all the simplicity and ease of use of a scripting language, along with more advanced software engineering tools typically found in compiled languages. Unlike some scripting languages, this combination makes Python useful for large-scale development projects. As a preview, here are some of the main things we'll find in Python's toolbox:

Dynamic typing

Python keeps track of the kinds of objects your program uses when it runs; it doesn't require complicated type and size declarations in your code. In fact, as we'll see in Chapter 4, there is no such thing as a type or variable declaration anywhere to be found in Python.

Automatic memory management

Python automatically allocates and reclaims (" garbage collects") objects when no longer used, and most grow and shrink on demand. Python keeps track of low-level memory details so you don't have to.

Programming-in-the-large support

For building larger systems, Python includes tools such as modules, classes, and exceptions. These tools allow you to organize systems into components, use OOP to reuse and customize code, and handle events and errors gracefully.

Built-in object types

Python provides commonly used data structures such as lists, dictionaries, and strings, as an intrinsic part of the language; as we'll see, they're both flexible and easy to use. For instance, built-in objects can grow and shrink on demand, can be arbitrarily nested to represent complex information, and more.

Built-in tools

To process all those object types, Python comes with powerful and standard operations, including concatenation (joining collections), slicing (extracting sections), sorting, mapping, and more.

Library utilities

For more specific tasks, Python also comes with a large collection of pre-coded library tools that support everything from regular-expression matching to networking. Python's library tools are where much of the application-level action occurs.

Third-party utilities

Because Python is freeware, it encourages developers to contribute precoded tools that support tasks beyond Python's built-ins; you'll find free support for COM, imaging, CORBA ORBs, XML, database vendors, and much more.

Despite the array of tools in Python, it retains a remarkably simple syntax and design. The result is a powerful programming tool, which retains the usability of a scripting language.

1.6.5 It's Mixable

Python programs can be easily "glued" to components written in other languages, in a variety of ways. For example, Python's C API lets C programs call and be called by Python programs flexibly. That means you can add functionality to the Python system as needed, and use Python programs within other environments or systems.

For example, by mixing Python with libraries coded in languages such as C or C++, it becomes an easy-to-use frontend language and customization tool. As mentioned earlier, this also makes Python good at rapid prototyping; systems may be implemented in Python first to leverage its speed of development, and later moved to C for delivery, one piece at a time, according to performance demands.

1.6.6 It's Easy to Use

To run a Python program, you simply type it and run it. There are no intermediate compile and link steps like there are for languages such as C or C++. Python executes programs immediately, which makes for both an interactive programming experience and rapid turnaround after program changes.

Of course, development cycle turnaround is only one aspect of Python's ease of use. It also provides a deliberately simple syntax and powerful high-level built-in tools. In fact, some have gone so far as to call Python "executable pseudocode." Because it eliminates much of the complexity in other tools, Python programs are simpler, smaller, and more flexible than equivalent programs in language like C, C++, and Java.

1.6.7 It's Easy to Learn

This brings us to the topic of this book: compared to other programming languages, the core Python language is remarkably easy to learn. In fact, you can expect to be coding significant Python programs in a matter of days (and perhaps in just hours, if you're already an experienced programmer). That's good news both for professional developers seeking to learn the language to use on the job, as well as for end users of systems that expose a Python layer for customization or control. Today, many systems rely on the fact that end users can quickly learn enough Python to tailor their Python customization's code onsite, with little or no support.