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class Object
# Invokes the public method whose name goes as first argument just like
# +public_send+ does, except that if the receiver does not respond to it the
# call returns +nil+ rather than raising an exception.
#
# This method is defined to be able to write
#
# @person.try(:name)
#
# instead of
#
# @person ? @person.name : nil
#
# +try+ returns +nil+ when called on +nil+ regardless of whether it responds
# to the method:
#
# nil.try(:to_i) # => nil, rather than 0
#
# Arguments and blocks are forwarded to the method if invoked:
#
# @posts.try(:each_slice, 2) do |a, b|
# ...
# end
#
# The number of arguments in the signature must match. If the object responds
# to the method the call is attempted and +ArgumentError+ is still raised
# otherwise.
#
# If +try+ is called without arguments it yields the receiver to a given
# block unless it is +nil+:
#
# @person.try do |p|
# ...
# end
#
# Please also note that +try+ is defined on +Object+, therefore it won't work
# with instances of classes that do not have +Object+ among their ancestors,
# like direct subclasses of +BasicObject+. For example, using +try+ with
# +SimpleDelegator+ will delegate +try+ to the target instead of calling it on
# delegator itself.
def try(*a, &b)
if a.empty? && block_given?
yield self
else
public_send(*a, &b) if respond_to?(a.first)
end
end
# Same as #try, but will raise a NoMethodError exception if the receiving is not nil and
# does not implemented the tried method.
def try!(*a, &b)
if a.empty? && block_given?
yield self
else
public_send(*a, &b)
end
end
end
class NilClass
# Calling +try+ on +nil+ always returns +nil+.
# It becomes specially helpful when navigating through associations that may return +nil+.
#
# nil.try(:name) # => nil
#
# Without +try+
# @person && !@person.children.blank? && @person.children.first.name
#
# With +try+
# @person.try(:children).try(:first).try(:name)
def try(*args)
nil
end
def try!(*args)
nil
end
end
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