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# note that elem is accessible outside of the for loop
elem # => 3
# good
arr.each { |elem| puts elem }
# elem is not accessible outside each block
elem # => NameError: undefined local variable or method `elem'
----
=== `then` in Multi-line Expression [[no-then]]
Do not use `then` for multi-line `if`/`unless`/`when`/`in`.
[source,ruby]
----
# bad
if some_condition then
# body omitted
end
# bad
case foo
when bar then
# body omitted
end
# bad
case expression
in pattern then
# body omitted
end
# good
if some_condition
# body omitted
end
# good
case foo
when bar
# body omitted
end
# good
case expression
in pattern
# body omitted
end
----
=== Condition Placement [[same-line-condition]]
Always put the condition on the same line as the `if`/`unless` in a multi-line conditional.
[source,ruby]
----
# bad
if
some_condition
do_something
do_something_else
end
# good
if some_condition
do_something
do_something_else
end
----
=== Ternary Operator vs `if` [[ternary-operator]]
Prefer the ternary operator(`?:`) over `if/then/else/end` constructs.
It's more common and obviously more concise.
[source,ruby]
----
# bad
result = if some_condition then something else something_else end
# good
result = some_condition ? something : something_else
----
=== Nested Ternary Operators [[no-nested-ternary]]
Use one expression per branch in a ternary operator.
This also means that ternary operators must not be nested.
Prefer `if/else` constructs in these cases.
[source,ruby]
----
# bad
some_condition ? (nested_condition ? nested_something : nested_something_else) : something_else
# good
if some_condition
nested_condition ? nested_something : nested_something_else