Variable Scope in Ruby

an intro into variables and variable scope

Transcript

1. variable scope in ruby a techno-preso-blogpost 16.10.13 charlotte chang
2. first, the preamble the hardest thing about writing anything is the examples. ...picking good examples carries a book, right? If the examples are bad, you hate them. If the examples are engaging...they teach you the right things, then they keep your attention. -sandy metz Ruby Rogues
3. many myriad missive mischievous multifarious massive multitudinous macabre mayhem merry magnificent marauding Mixed Metaphors
4. Part I. mini journey into the veritable variable
5. Variables are like nicknames. Remember when everyone used to call you Stinky Pete? People would say, “Get over here, Stinky Pete!” And everyone miraculously knew that Stinky Pete was you." -Why’s Poignant Guide to Ruby
6. plain lowercase words can include letters, digits and _ syntax kale fat_puggle fly_hitops snuggie sarcasm _8tracks pink_scrunchie accordion bear_trap
7. something you want to use frequently && you don’t want to type it over and over and over and over and over and over and over and over and over and over and over over ove why?
8. something you want to use frequently this is a function but it could be... else?
9. beaker beaker these are variables where you could put
10. beaker beaker 6 * volume(beaker) == 2 * volume(beaker)
11. 1 * volume(beaker)
12. variables can be named anything you want but they should be relevant and by the way, naming your variables with the same name is a bad idea.
13. types of variables global $ instance @ or self. local [a-z] or _ constant [A-Z] class @@
14. Part II. How I Learned to Stop Worrying and Love the Ruling Class
15. newb’s journey into variable scope 5.steps do | easy | .hold
16. newb’s journey into variable scope 5.steps do | easy | 1 5 Bourgeoisie Obamacare
17. newb’s journey into variable scope 5.steps do | easy | 1 2 3 4 5 Bourgeoisie BenevolentBourgeoisie Canada OnePercent Obamacare
19. can the baker use the brewmaster’s tools? can the carpenter use the baker’s bandages? local variable scope 1
20. what do you notice about the medicine(s)? local variable scope 1
21. DRY Don’t Repeat Yourself The Pragmatic Programmer Andy Hunt and Dave Thomas 1
23. 2 class instance variable scope who has the medicine? who can use the medicine? when is medicine used?
24. Do one thing. curly’s law 2
26. 3 constant scope when would the brewmaster get medicine? when would the brewmaster go to the doctor?
27. 3 constant scope who has to use wait_time? when/how does the brewmaster have to wait_time?
28. 3 constant scope what if there was a wait for beer? next year, the wait time increases to 10 weeks, what happens?
29. 3 No magic numbers. Steve McConnell
31. 4 class variable scope do the brewmaster and the carpenter go to the same doctor? can the doctor prescribe medicine independent of a pharmaceutical company? if a doctor gets sued, where can s/he get money from?
32. 4 Class instance variables should usually be preferred over class variables. Github's Ruby Styleguide
34. 5 global variable scope who can access healthcare? can new instances of America have healthcare? does America know where healthcare comes from?
35. 1. what is a variable? 2. what are the types of variables? 3. what is variable scope? 4. what are the types of variable scope? recap 1 2 3 4 5 Bourgeoisie BenevolentBourgeosie Canada OnePercent Obamacare local class instance constant class global
36. <%= some_witty_ending %>