Mercurial > repos > other > SevenLanguagesInSevenWeeks

annotate 2-Io/day1-singletons.io @ 34:3d41d9d72cc9

Find changesets by keywords (author, files, the commit message), revision number or hash, or revset expression.
Add Day 1 code for Singletons (including booleans)
author IBBoard <dev@ibboard.co.uk>
date Wed, 06 Sep 2017 19:29:20 +0100
parents
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
34
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
1 # Conditions are simple and like most languages
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
2 # Not mentioned yet, but found by necessity: we can use brackets!
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
3 (4 < 5) println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
4 # Unlike Python, Io uses lower case for booleans
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
5 (true and false) println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
6 # Truthy values are more like Python than C:
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
7 (true and 6) println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
8 (true and 0) println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
9
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
10 # But true, false and nil are all just objects
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
11 # Albeit special "singleton" objects where cloning gets the same object
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
12 true clone println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
13 false clone println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
14 nil clone println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
15 (true == true clone) println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
16
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
17 # We can create our own singletons by altering the clone method to return the class
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
18 # Highlander: THERE CAN BE ONLY ONE!
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
19 Highlander := Object clone
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
20 Highlander clone := Highlander
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
21 Highlander println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
22 Highlander clone println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
23 highlander1 := Highlander clone
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
24 highlander2 := Highlander clone
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
25 (highlander1 == highlander2) println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
26 # Normally cloning gives different objects with different IDs
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
27 obj1 := Object clone
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
28 obj2 := Object clone
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
29 (obj1 == obj2) println
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
30
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
31 # And with great power comes great responsibility.
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
32 # Object is not special. It is not protected in any way.
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
33 # DO NOT do this in real code!
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
34 Object clone := "Ooops!"
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
35 obj3 := Object clone
3d41d9d72cc9 Add Day 1 code for Singletons (including booleans)
IBBoard <dev@ibboard.co.uk>
parents:
diff changeset
36 obj3 println