Ex. 37 - Keyword Flashcards
BEGIN
Run this block when the script starts
BEGIN { puts “hi” }
END
Run this block when the script is done
END {puts “hi” }
alias
Create another name for a function.
alias X Y
and
Logical and, but lower priority than &&.
puts “Hello” and “Goodbye”
begin
Start a block, usually for exceptions.
begin end
break
Break out of a loop right now.
while true; break; end
case
Case style conditional, like an if.
case X; when Y; else; end
class
Define a new class.
class X; end
def
Define a new function.
def X( ); end
defined?
Is this class/function/etc. defined already?
defined? Class == “constant”
do
Create a block that maybe takes a parameter.
(0..5).each do |x| puts x end
else
Else conditional.
if X; else; end
elsif
Else if conditional
if X; elsif Y; else; end
end
Ends blocks, functions, classes, everything
begin end # many others
ensure
Run this code whether an exception happens or not.
begin ensure end
for
For loop syntax. The .each syntax is preferred.
for X in Y; end
if
If conditional.
if X; end
in
In part of for-loops.
for X in Y; end
module
Define a new module
module X; end
next
Skip to the next element of a .each iterator.
(o..5).each { |y| next }
not
Logical not. But use ! instead.
not true == false
or
Logical or.
puts “Hello” or “Goodbye”
redo
Rerun a code block exactly the same.
(0..5).each { |i| redo if i > 2 }
rescue
Run this code if an exception happens.
begin rescue X; end
retry
In a rescue clause, says to try the block again.
(0..5).each { |i| retry if i > 2 }
return
Returns a value from a function. Mostly optional.
return X
self
The current object, class, or module.
defined? self == “self”
super
The parent class of this class.
super
then
Can be used with if optionally.
if true then puts “hi” end
undef
Remove a function definition from a class.
undef X
unles
Inverse of if.
unless false then puts “not” end
until
Inverse of while, execute block as long as false.
until false; end
when
Part of case conditionals.
Case X; when Y; else; end
while
While loop.
while true; end
yield
Pause and transfer control to the code block.
yield
