ISBN links

When mentioning books in a document it s handy for a reader to have a link to an online resource about that book. Linking to an online bookstore with product descriptions is probably the best way to achieve this.

For ease of use, again we want to find a macro that allows us to simplify things as much as possible. A usage pattern like \BOOK<Title> would be sufficient, but to build the link we need something unique to each book. ISBN numbers are well suited for this purpose, so a parameter can take it: \BOOK{isbn=0596000278}<Programming Perl> (which produces this link: " Programming Perl").

And here is a macro definition for this:

    +BOOK:\L{url="http://www.amazon.com/gp/product/__isbn__" target=_blank}<__body__>

More sophisticated versions could add even more convenience. For example, all book references could be collected and re-presented in a final "books" chapter, or literature list. See the Collections example for ideas.

As an additional benefit of macro use, it is easy to adapt the links to a certain country or to another bookstore. As a macro is defined in one place, all one has to do is to make the definition conditional:

    ? flagSet(booksus)
  
    +BOOK:\L{url="http://www.amazon.com/gp/product/__isbn__" target=_blank}<__body__>
  
    ? flagSet(booksde)
  
    +BOOK:\L{url="http://www.amazon.de/exec/obidos/ASIN/__isbn__" target=_blank}<__body__>
  
    ? 1

Of course the principle of this macro is not only suitable for books, but adaptable to various other product categories with online informations.