Question

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Why are exclamation marks used in Ruby methods?

Hi All,

In ruby/rails I have seen some methods ended up with ! sign like

before_filter :authenticated!

just wonder what does mean by authenticated!, ‘!’ sign

thanks in advance

cheers

sameera

Answer 1

As a convention, identifier? are used as predicate names, and identifier! are used for the more destructive (or more dangerous) methods than the method which have same name without !.

Source

Example:

lstrip will return a new string with leading spaces removed thus original string is un-modified.
lstrip! will modify the string-in place