birt code 128

birt code 128

birt code 128

birt code 128

birt code 128

birt code 128,
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birt code 128,
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birt code 128,
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birt code 128,
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birt code 128,
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As you know from the previous section, creating functions is central to structured programming. So how do you define a function With the def (or function definition ) statement: def hello(name): return 'Hello, ' + name + '!' After running this, you have a new function available, called hello, which returns a string with a greeting for the name given as the only parameter. You can use this function just like you used the built-in ones: >>> print hello('world') Hello, world! >>> print hello('Gumby') Hello, Gumby! Pretty neat, huh Consider how you would write a function that returned a list of Fibonacci numbers. Easy! You just use the code from before, and instead of reading in a number from the user, you receive it as a parameter: def fibs(num): result = [0, 1] for i in range(num-2): result.append(result[-2] + result[-1]) return result After running this statement, you ve basically told the interpreter how to calculate Fibonacci numbers so now you don t have to worry about the details anymore. You simply use the function fibs: >>> [0, >>> [0, fibs(10) 1, 1, 2, 3, 5, 8, 13, 21, 34] fibs(15) 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377]

Figure 12-2. Profile Wizard When you are ready to create the CSV file, click the Run Profile link located on the left navigation bar. Click Run Profile in Popup to start the exporting, which creates a pop-up window that displays debug messages for you to view. When that is complete, navigate to the /var/export/ directory (unless you changed the export path in the Profile Wizard) and you ll see the newly created CSV file.

Next, for the many-to-many mapping between the authors and books, add the has_and_belongs_to_many mapping to app/models/book.rb as follows: class Book < ActiveRecord::Base has_and_belongs_to_many :authors belongs_to :publisher end

The names num and result are quite arbitrary in this example, but return is important. The return statement is used to return something from the function (which is also how we used it in the preceding hello function).

Open the file up in your favorite editor or spreadsheet application. All the columns should be labeled. From this point on, it s pretty self-explanatory. Add a new row with your new products and repeat. If you use a spreadsheet application, make sure that you select Save As CSV when you are complete.

Note ActiveRecord tries to guess the name of the join table, authors_books, by combining the two table names. In our example, ActiveRecord will look for a table named authors_books, not books_authors, since the string authors comes before books when compared in lexical order.

Note If your client already has a CSV file with product information, you have to create a script that will read the

If you want to document your functions so that you re certain that others will understand them later on, you can add comments (beginning with the hash sign, #). Another way of writing comments is simply to write strings by themselves. Such strings can be particularly useful in some places, such as right after a def statement (and at the beginning of a module or a class you learn more about those later in the book). If you put a string at the beginning of a function, it is stored as part of the function and is called a docstring. The following code demonstrates how to add a docstring to a function: def square(x): 'Calculates the square of the number x.' return x*x The docstring may be accessed like this: >>> square.__doc__ 'Calculates the square of the number x.'

We also want to be able to access the books from the author s side of the relationship, so change app/models/author.rb as follows: class Author < ActiveRecord::Base has_and_belongs_to_many :books validates_presence_of :first_name, :last_name def name "#{first_name} #{last_name}" end end That takes care of the ActiveRecord mappings, but we also want to make sure only valid books are stored in the database. This can be done with validations, which we introduced in 2.

file and map it to the same columns as Magento s CSV file. (This is a simple programming task, but we won t cover it here.)

underscores in the attribute name mean that this is a special attribute. Special or magic attributes like this are discussed in 9.