.NET/Java PDF, Tiff, Barcode SDK Library

The last important aspect of regular expressions you need to understand at this stage is character classes. These allow you to match against a specific set of characters. For example, you can scan through all the vowels in a string:

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By now you are probably wondering why anyone would ever want such a thing as an immutable (unchangeable) sequence. Can t you just stick to lists and leave them alone when you don t want them to change Basically, yes. However, there are two important reasons why you need to know about tuples: They can be used as keys in mappings lists can t be. (You may remember that mappings were mentioned in the chapter introduction. You ll learn more about them in 4.) They are returned by some built-in functions and methods, which means that you have to deal with them. As long as you don t try to change them, dealing with them most often means treating them just like lists (unless you need methods such as index and count, which tuples don t have). In general, lists will probably be adequate for all your sequencing needs.

"This is a test".scan(/[aeiou]/) { |x| puts x }

6

inside the square brackets, like so:

"This is a test".scan(/[a-m]/) { |x| puts x }

For a quick presentation for which you don t plan to print handouts, write short notes to yourself in the notes area of the slides of the storyboard. For now, spell out as much of your explanation as you can at this stage of the presentation if you re pressed for time, write what you can at this point and then expand on your text in more detail later. Or you can use a digital recorder to capture your thoughts as you re speaking about each slide and then transcribe the recording later and paste the text passages into the corresponding notes areas. You also might try using speech recognition software such as Dragon Naturally Speaking or one of the dictation services such as SpeakWrite Voice-toDocument Service that allow you to speak your narration into a telephone and then the service sends you an e-mail message with a transcription a short time later.

This scan matches all lowercase letters between a and m. Regular expressions can be complex and confusing, and entire books larger than this one have been dedicated to them. Most coders only need to understand the basics, as the more-advanced techniques will become apparent with time, but they re a powerful tool when you experiment with, and master, them. You ll be using, and expanding upon, all the techniques covered in this section in code examples throughout the rest of the book.

Let s review some of the most important concepts covered in this chapter: Sequences. A sequence is a data structure in which the elements are numbered (starting with zero). Examples of sequence types are lists, strings, and tuples. Of these, lists are mutable (you can change them), whereas tuples and strings are immutable (once they re created, they re fixed). Parts of a sequence can be accessed through slicing, supplying two indices, indicating the starting and ending position of the slice. To change a list, you assign new values to its positions, or use assignment to overwrite entire slices. Membership. Whether a value can be found in a sequence (or other container) is checked with the operator in. Using in with strings is a special case it will let you look for substrings. Methods. Some of the built-in types (such as lists and strings, but not tuples) have many useful methods attached to them. These are a bit like functions, except that they are tied closely to a specific value. Methods are an important aspect of object-oriented programming, which we look at later, in 7.

As with WEBrick and Mongrel, the XML-RPC server can also use other classes directly, as with WEBrick s servlets. For example:

class OurClass def some_method "Some test text" end end require 'xmlrpc/server' server = XMLRPC::Server.new(1234) server.add_handler(XMLRPC::iPIMethods('sample'), OurClass.new) trap("INT") { server.shutdown } server.serve