10 - COLLECTION IDIOMS

Summary

If you have read The Smalltalk Best Practice Patterns, you can see in this column the beginnings of the section in the book on collections. Once again, I mined the material from the image. Thinking back, I'm amazed at how important reading the image has been to me. I can remember being incredibly frustrated at having to spend all day looking for the method or class that I wanted, but then realizing at the end of the day that I had gotten more accomplished with six hours of reading and ten minutes of typing than I used to accomplish with ten hours of typing.

We may underestimate the value of a shared body of literature (the image) in creating and sustaining the Smalltalk culture. Perhaps that's why the visual “wire-and-fire” front-ends failed to have much impact-there was no corpus of visual code that everyone routinely consulted.

Our previous column focused on enumeration methods and how to use all of them to advantage. This column covers the common collection classes, how they are implemented, when you should use them, and when you should be careful.

COLLECTION CLASSES

ARRAY

Use an Array if you know the size of the collection when you create it and if the indices into the elements (the first argument to at: and at:put:) are consecutive integers between one and the size of the array.