Simple .NET/ASP.NET PDF document editor web control SDK

Sequences are useful when you want to work with a collection of values. You might have a sequence representing a person in a database, with the first element being their name, and the second their age. Written as a list (the items of a list are separated by commas and enclosed in square brackets), that would look like this: >>> edward = ['Edward Gumby', 42] But sequences can contain other sequences, too, so you could make a list of such persons, which would be your database: >>> edward = ['Edward Gumby', 42] >>> john = ['John Smith', 50] >>> database = [edward, john] >>> database [['Edward Gumby', 42], ['John Smith', 50]] This chapter begins with some operations that are common to all sequences, including lists and tuples. These operations will also work with strings, which will be used in some of the examples, although for a full treatment of string operations, you have to wait until the next chapter. After dealing with these basics, we start working with lists and see what s special about them. After lists, we come to tuples, which are very similar to lists, except that you can t change them.

winforms pdf 417 reader, winforms qr code reader, winforms upc-a reader, winforms data matrix reader, winforms ean 128 reader, winforms ean 13 reader, itextsharp remove text from pdf c#, c# replace text in pdf, winforms code 39 reader, itextsharp remove text from pdf c#,

The initialize method sets up each newly created object and uses the options hash to populate two class variables, @name and @data. External access to @name is provided courtesy of attr_reader. File.open, along with the read method, opens the data file and reads in the full contents to be processed by the YAML library. YAML.load converts the YAML data into the original hash data structure and assigns it to the @data class variable. If the data file opening or YAML processing fails, an exception is raised, as the bot cannot function without data. Now you can create the greeting and farewell methods that display a random greeting and farewell message from the bot s data set. These methods are used when people first start to use the bot or just before the bot client exits.

In order to align your own assumptions about communication with what researchers accept about the way human memory works, you ll need to drop the old pipeline metaphor and pick up a new metaphor the eye of the needle, as shown in Figure 2-7..

def greeting @data[:responses][:greeting][rand(@data[:responses][:greeting].length)] end def farewell @data[:responses][:farewell][rand(@data[:responses][:farewell].length)] end

excellent opportunity to create a private method that retrieves a random phrase from a selected response group:

2

private def random_response(key) random_index = rand(@data[:responses][key].length) @data[:responses][key][random_index].gsub(/\[name\]/, @name) end

Note Python has a basic notion of a kind of data structure called a container, which is basically any object that can contain other objects. The two main kinds of containers are sequences (such as lists and tuples) and mappings (such as dictionaries). While the elements of a sequence are numbered, each element in a mapping has a name (also called a key). You learn more about mappings in 4. For an example of a container type that is neither a sequence nor a mapping, see the discussion of sets in 10.

This method simplifies the routine of taking a random phrase from a particular phrase set in @data. The second line of random_response performs a substitution so that any responses that contain [name] have [name] substituted for the bot s name. For example, one of the demo greeting phrases is Hi. I m [name]. Want to chat However, if you created the bot object and specified a name of Fred, the output would appear as Hi. I m Fred. Want to chat

FIGURE 2-7 The limited capacity of working memory to process new information creates a narrow pas-

Note Remember that a private method is a method that cannot be called from outside the class itself.

As random_response is only needed internally to the class, it s a perfect candidate to be a private method.

When stated like this, subclasses and superclasses are easy to understand. But in objectoriented programming, the subclass relation has important implications because a class is defined by what methods it supports. All the instances of a class have these methods, so all the instances of all subclasses must also have them. Defining subclasses is then only a matter of defining more methods (or, perhaps, overriding some of the existing ones). For example, Bird might supply the method fly while Penguin (a subclass of Bird) might add the method eatFish. When making a penguin class, you would probably also want to override a method of the superclass, namely the fly method. In a Penguin instance, this method should either do nothing, or possibly raise an exception (see 8), given that penguins can t fly.

sage much like the eye of a needle that stands between the information you present sensory memory and the information that is integrated into long-term memory.

Let s update greeting and farewell to use random_response:

Isn t separating common functionality into distinct methods great These methods now look a lot simpler and make immediate sense compared to the jumble they contained previously.