Intro to Ruby Book Flashcards
variables
used to store information to be referenced and manipulated in a computer program, provide a way of labeling data with a descriptive name
like containers that hold info
variables
.chomp
used after any string to remove the extra characters at the end
method
(early defintion) pieces of reusable code that a program can execute many times
How is a block delimited?
IT is delimited by either { }, or do/end
Ruby methods ALWAYS return the evaluated result of the last line of the expression unless an explicit xxxx comes before it.
RETURN
Method analogy
Like a hammer in your backback
Does the pop method mutate the caller?
Yes, the original array variable is modified
How do you add an item back to an array permanently?
array.push
OR («)
The _____ method iterates over an array applying a block to each element of the array and returns a new array with those results.
map or collect method
Is a map/collect method destructive? (Does it mutate the caller)
No it does not mutate the caller
Object ID
Every Object has a unique object ID
x.object_id
How do you get two of the same object ID?
if 2 immutable objects have the same value they have the same object ID
The calling object
The object that the method is invoked upon
What can be passed to methods as arguments
Only objects (not variables)
Usually ____ have a “meaningful” return value that is meant to be “used” in some way
non-mutating methods
Map vs. Each
If you want to change your return value: use map. If you want to use the same return value that you started with use .each. (Each is more flexible).
What is the return value of .each?
The same value as the original array
What will the input be?
def speak(words)
puts words
end
speak(“There are around 700 separate programming languages”)
You can pass in a string as an argument without putting it in a local valuable first.
output: There are around 700 separate programming languages
year = 1986
def virus(year)
puts “The first computer virus was created in #{year}
end
virus
ERROR
default paramaters
you can invoke the method without passing an argument
Arguments are used in….
method invocations
Parameters are used in…
method definitions
