Ruby Pocket Reference

Reserved Words

Table 1 lists Ruby’s reserved words or keywords.

Table 1. Ruby’s reserved words

Reserved word	Description
BEGIN	Code, enclosed in { }, to run before the program runs.
END	Code, enclosed in { }, to run when the program ends.
alias	Creates an alias for an existing method, operator, or global variable.
and	Logical operator; same as && except and has lower precedence.
begin	Begins a code block or group of statements; closes with end.
break	Terminates a while or until loop, or a method inside a block.
case	Compares an expression with a matching when clause; closes with end. See when.
class	Defines a class; closes with end.
def	Defines a method; closes with end.
defined?	A special operator that determines whether a variable, method, super method, or block exists.
do	Begins a block, and executes code in that block; closes with end.
else	Executes following code if previous conditional is not true, set with if, elsif, unless, or case. See if, elsif.
elsif	Executes following code if previous conditional is not true, set with if or elsif.
end	Ends a code block (group of statements) started with begin, class, def, do, if, etc.
ensure	Always executes at block termination; use after last rescue.
false	Logical or Boolean false; instance of FalseClass; a pseudovariable. See true.
for	Begins a for loop; used with in.
if	Executes code block if conditional statement is true. Closes with end. Compare unless, until.
in	Used with for loop. See for.
module	Defines a module; closes with end.
next	Jumps to the point immediately before ...