/Doc/tutorial/appetite.rst
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- .. _tut-intro:
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- Whetting Your Appetite
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- If you do much work on computers, eventually you find that there's some task
- you'd like to automate. For example, you may wish to perform a
- search-and-replace over a large number of text files, or rename and rearrange a
- bunch of photo files in a complicated way. Perhaps you'd like to write a small
- custom database, or a specialized GUI application, or a simple game.
- If you're a professional software developer, you may have to work with several
- C/C++/Java libraries but find the usual write/compile/test/re-compile cycle is
- too slow. Perhaps you're writing a test suite for such a library and find
- writing the testing code a tedious task. Or maybe you've written a program that
- could use an extension language, and you don't want to design and implement a
- whole new language for your application.
- Python is just the language for you.
- You could write a Unix shell script or Windows batch files for some of these
- tasks, but shell scripts are best at moving around files and changing text data,
- not well-suited for GUI applications or games. You could write a C/C++/Java
- program, but it can take a lot of development time to get even a first-draft
- program. Python is simpler to use, available on Windows, Mac OS X, and Unix
- operating systems, and will help you get the job done more quickly.
- Python is simple to use, but it is a real programming language, offering much
- more structure and support for large programs than shell scripts or batch files
- can offer. On the other hand, Python also offers much more error checking than
- C, and, being a *very-high-level language*, it has high-level data types built
- in, such as flexible arrays and dictionaries. Because of its more general data
- types Python is applicable to a much larger problem domain than Awk or even
- Perl, yet many things are at least as easy in Python as in those languages.
- Python allows you to split your program into modules that can be reused in other
- Python programs. It comes with a large collection of standard modules that you
- can use as the basis of your programs --- or as examples to start learning to
- program in Python. Some of these modules provide things like file I/O, system
- calls, sockets, and even interfaces to graphical user interface toolkits like
- Tk.
- Python is an interpreted language, which can save you considerable time during
- program development because no compilation and linking is necessary. The
- interpreter can be used interactively, which makes it easy to experiment with
- features of the language, to write throw-away programs, or to test functions
- during bottom-up program development. It is also a handy desk calculator.
- Python enables programs to be written compactly and readably. Programs written
- in Python are typically much shorter than equivalent C, C++, or Java programs,
- for several reasons:
- * the high-level data types allow you to express complex operations in a single
- statement;
- * statement grouping is done by indentation instead of beginning and ending
- brackets;
- * no variable or argument declarations are necessary.
- Python is *extensible*: if you know how to program in C it is easy to add a new
- built-in function or module to the interpreter, either to perform critical
- operations at maximum speed, or to link Python programs to libraries that may
- only be available in binary form (such as a vendor-specific graphics library).
- Once you are really hooked, you can link the Python interpreter into an
- application written in C and use it as an extension or command language for that
- application.
- By the way, the language is named after the BBC show "Monty Python's Flying
- Circus" and has nothing to do with reptiles. Making references to Monty
- Python skits in documentation is not only allowed, it is encouraged!
- Now that you are all excited about Python, you'll want to examine it in some
- more detail. Since the best way to learn a language is to use it, the tutorial
- invites you to play with the Python interpreter as you read.
- In the next chapter, the mechanics of using the interpreter are explained. This
- is rather mundane information, but essential for trying out the examples shown
- later.
- The rest of the tutorial introduces various features of the Python language and
- system through examples, beginning with simple expressions, statements and data
- types, through functions and modules, and finally touching upon advanced
- concepts like exceptions and user-defined classes.