ReadStream in Smalltalk

Walk a collection with a cursor.

"A ReadStream walks a collection with a cursor."
| feed |
feed := ReadStream on: #('frisket' 'tympan' 'platen' 'chase').

Transcript show: 'First out: ', feed next; cr.
Transcript show: 'Then: ', feed next; cr.
Transcript show: 'Peek: ', feed peek; cr.
Transcript show: 'Still next: ', feed next; cr.

[feed atEnd] whileFalse: [
    Transcript show: 'Draining: ', feed next; cr].
Transcript show: 'Empty? ', feed atEnd printString; cr.

How it works

1. next consumes one element; peek looks without taking.
2. atEnd guards the draining loop.
3. Streams unify collections and files behind one protocol.

Keywords and builtins used here

• ReadStream
• Transcript
• atEnd
• cr
• next
• peek
• printString

The run, in numbers

Lines

12

Characters to type

431

Tokens

77

Three-star pace

60 tpm

At the three-star pace of 60 tokens a minute, this run takes about 77 seconds.

Type this snippet

Step 2 of 2 in Streams, step 25 of 31 in Language basics.

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