Modeling Language: Plurals, Part 2

You can improve plural to work correctly with more words. If the project is not already open, please reload it. (The suggested file name was U2-Plural.)

  1. Abstraction: Make a on just one category, words that end with the letter h.
    • Start with a list of the words you want it to work for.
    • This specialist block should work correctly for words that fit its specialty because the plural block should never give words to plural-h unless those words end with h.
    • Test with a variety of words to make sure it works the way you want. Then use map to test it on the entire list you made earlier.
  2. Abstraction: Language often has special cases. In English, the plurals of some nouns add s; some add es; nouns like calf and fly become calves and flies, changing their final letters before adding es. And more. For a programming task this complex, it's (generally) best to break it into parts, handle each part separately with its own procedure (its own block), and then have the "top-level" block—in this case, plural, itself—use those specialists. That is, instead of coding every little detail directly in plural, it is cleaner and clearer to make plural look something like this.

    Showing the structure of the method—just the overall strategy—in the "top-level" block and leaving the details to separate blocks is one part of an important computer science idea called abstraction. Abstraction keeps your code clear, readable, and more easily debugged. It will also help your code be more flexible.

  3. When you trust your new specialist block, edit plural to use the specialist. Test (you can use map) to make sure plural still works for all the words it used to work for, as well as the new ones.
  4. Create plural-y to handle words like and
  5. Remember, any specialist can make mistakes if it's asked to do a job that isn't its specialty.

    Make sure plural gives it only the job it knows how to handle correctly.

  1. Because you know what
  2. Extend plural to handle another special case. Use a special-purpose block for your special case to keep plural from becoming cluttered.
  3. Right now, if plural is given a word with a space at the end, it leaves that space in the plural, like this: . You already have a block that specializes in making plurals of words that don't have a space at the end. Use it.
  4. Surprise! Once plural works for a single space at the end of a word, try giving it . That works!! But why?!