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ST 4U 314: Reading Collections with Streams

November 28, 2012 9:59:10.964

Today's Smalltalk 4 You looks at readng objects from collections in Smalltalk - streams are hardly limited to strings. If you have trouble viewing it here in the browser, you can also navigate directly to YouTube. To watch now, click on the image below:

read streams.

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Today we'll have a look at reading arbitrary collections via streams. In Smalltalk, streams can be used to read any collection (not just strings). For example: here we set up a ByteArray, and then read from it:

stream := #[12 23 34 78 99] readStream.
collection := OrderedCollection new.
collection add: stream next.
collection skip: 2.
collection add: stream next.

If you inspect the results, you'll see the collection #(12 78). You can do the same with collections of disparate objects:

stream2 := #('one' 2 'four' 16.2 $F 81) readStream.
collection2 := OrderedCollection new.
collection2 add: stream2 next.
collection2 skip: 2.
collection2 add: stream2 next.

Inspecting the results will give you the collection #('one' 16.2). Next time, we'll look at writing collections using streams.

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posted by James Robertson

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