Mercurial > repos > other > SevenLanguagesInSevenWeeks
annotate 2-Io/day1-self-study.io @ 38:e8407d4e72dd
Add code on reflection - basically involves the object returned by "proto" message
| author | IBBoard <dev@ibboard.co.uk> |
|---|---|
| date | Wed, 13 Sep 2017 20:11:52 +0100 |
| parents | 15eb99e79dd4 |
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| rev | line source |
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| 35 | 1 #Truthiness: |
| 2 # We already know that 0 is truthy | |
| 3 (true and 0) println | |
| 4 # Empty strings are apparently truthy | |
| 5 (true and "") println | |
| 6 # As are empty lists | |
| 7 (true and list()) println | |
| 8 # But nil is falsey | |
| 9 (true and nil) println | |
| 10 # So basically anything except `false` and `nil` is truthy | |
| 11 | |
| 12 # = vs := vs ::= | |
| 13 # Obvious part so far is that you must create with := before being able to assign with plain = | |
| 14 myvar := Object clone | |
| 15 myvar println | |
| 16 myvar = Object clone | |
| 17 # Docs say: | |
| 18 # ::= Creates slot, creates setter, assigns value | |
| 19 # := Creates slot, assigns value | |
| 20 # = Assigns value to slot if it exists, otherwise raises exception | |
| 21 # But what is a "setter" in this context? | |
| 22 myvar foo ::= Object clone | |
| 23 myvar println | |
| 24 # It seems we get a "setX" method, which helps us do some things in certain contexts: | |
| 25 # https://stackoverflow.com/a/5977757 | |
| 26 | |
| 27 # What slots does a prototype support? Direct ones are human readable in the output | |
| 28 myvar proto println | |
| 29 # But they're not listed indirectly | |
| 30 SubClass := Object clone | |
| 31 myvar2 := SubClass clone | |
| 32 myvar2 proto println | |
| 33 # Can we find it out programattically? | |
| 34 # It's not recursive, but the type should tell us: | |
| 35 myvar2 type proto println | |
| 36 # Except the value of `type` is just a string (or Sequence in Io), so it doesn't | |
| 37 myvar2 type proto type println | |
| 38 # Or, of course, a Prototype is a named object that starts with a capital letter | |
| 39 # So we can just use slotNames to get them programmatically (but that only shows direct slots) | |
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36
15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
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changeset
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40 myvar slotNames println |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
35
diff
changeset
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41 # And to get the parent ones then we just chain "proto" |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
35
diff
changeset
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42 myvar proto slotNames println |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
35
diff
changeset
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43 myvar proto proto slotNames println |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
35
diff
changeset
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44 # If I knew enough Io then I'd do a recursion loop and walk up until proto == Object |
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38
e8407d4e72dd
Add code on reflection - basically involves the object returned by "proto" message
IBBoard <dev@ibboard.co.uk>
parents:
36
diff
changeset
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45 # Update: See day2-reflection.io! |
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36
15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
35
diff
changeset
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46 |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
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diff
changeset
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47 |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
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diff
changeset
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48 |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
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changeset
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49 #Execute methods by slot name - use "perform" |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
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changeset
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50 SubClass method1 := method("Method 1 was called" println) |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
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diff
changeset
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51 SubClass method2 := method("Method 2 was called" println) |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
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changeset
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52 myvar2 perform("method1") |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
35
diff
changeset
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53 myvar2 perform("method2") |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
35
diff
changeset
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54 |
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15eb99e79dd4
Call methods by name and fix slot name printing
IBBoard <dev@ibboard.co.uk>
parents:
35
diff
changeset
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55 |
| 35 | 56 |
| 57 # Is Io strongly or weakly typed? | |
| 58 (1 + 1) println | |
| 59 (1 + "one") println | |
| 60 # Exception: argument 0 to method '+' must be a Number, not a 'Sequence' | |
| 61 # Therefore strongly typed |