Mercurial > repos > other > SevenLanguagesInSevenWeeks
annotate 1-Ruby/logic.rb @ 103:98be775c533c default tip
An odd "non-determinism" example from StackOverflow
It is clever, but doesn't make much sense as to how it gets its results
| author | IBBoard <dev@ibboard.co.uk> |
|---|---|
| date | Sun, 14 Jul 2019 13:44:13 +0100 |
| parents | e5b84cc7bc29 |
| children |
| rev | line source |
|---|---|
| 8 | 1 #! /usr/bin/env ruby |
| 2 | |
| 3 x = 4 | |
| 4 | |
| 5 # "if" block is "if… end" - no "then" required | |
| 6 if x == 4 | |
| 7 puts "x equals 4" | |
| 8 end | |
| 9 | |
| 10 # Python- and Perl-like following logic also works | |
| 11 puts "x equals 4" if x == 4 | |
| 12 puts "x equals 4" unless x != 4 | |
| 13 | |
| 14 # Negation has many forms. | |
| 15 # Simple logic: | |
| 16 if x != 5 | |
| 17 puts "x not equal 5" | |
| 18 end | |
| 19 | |
| 20 # Two options on negation | |
| 21 if !(x == 5) | |
| 22 puts "x not equal 5" | |
| 23 end | |
| 24 | |
| 25 if not x == 5 | |
| 26 puts "x not equal 5" | |
| 27 end | |
| 28 | |
| 29 # "unless" blocks instead of "if" | |
| 30 unless x != 4 | |
| 31 puts "x equal 4" | |
| 32 else | |
| 33 puts "x not equals 4" | |
|
12
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
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34 end |
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e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
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35 |
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e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
|
36 # "then" is optional, except in single line statement |
|
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
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37 if x == 4 then puts "x equal 4" end |
|
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
|
38 if x == 4 then |
|
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
|
39 puts "x equal 4" |
|
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
|
40 end |
|
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
|
41 if x == 4 |
|
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
|
42 puts "x equal 4" |
|
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
|
43 end |
|
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
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44 # The following line gives: |
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e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
|
45 # logic.rb:…: syntax error, unexpected tIDENTIFIER, expecting keyword_then or ';' or '\n' |
|
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
|
46 # if x == 4 puts "x equal 4" end |
|
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
|
47 # |
|
e5b84cc7bc29
Update logic script re: "then" in "if else" statements
IBBoard <dev@ibboard.co.uk>
parents:
8
diff
changeset
|
48 # if x == 4 puts "x equal 4" end |