我知道这是旧的，但它可能对其他人有帮助，因为这是我在谷歌上搜索这个问题时出现的第一件事。我“借用”了try的代码并实现了我自己的try_method方法，它的作用就像try一样，只是它在调用send之前首先检查该方法是否存在。我在 Object 中实现了它并将其放入初始化程序中，现在我可以在任何对象上调用它。
class Object
# Invokes the method identified by _method_, passing it any
# arguments specified, just like the regular Ruby <tt>Object#send</tt> does.
#
# *Unlike* that method however, a +NoMethodError+ exception will *not* be raised
# if the method does not exist.
#
# This differs from the regular Ruby <tt>Object#try</tt> method which only
# suppresses the +NoMethodError+ exception if the object is Nil
#
# If try_method is called without a method to call, it will yield any given block with the object.
#
# Please also note that +try_method+ is defined on +Object+, therefore it won't work with
# subclasses of +BasicObject+. For example, using try_method with +SimpleDelegator+ will
# delegate +try_method+ to target instead of calling it on delegator itself.
#
# ==== Examples
#
# Without +try_method+
# @person && @person.respond_to?(:name) && @person.name
# or
# (@person && @person.respond_to?(:name)) ? @person.name : nil
#
# With +try_method+
# @person.try_method(:name)
#
# +try_method+ also accepts arguments and/or a block, for the method it is trying
# Person.try_method(:find, 1)
# @people.try_method(:collect) {|p| p.name}
#
# Without a method argument try_method will yield to the block unless the receiver is nil.
# @person.try_method { |p| "#{p.first_name} #{p.last_name}" }
#--
# +try_method+ behaves like +Object#send+, unless called on +NilClass+ or a class that does not implement _method_.
def try_method(method=nil, *args, &block)
if method == nil && block_given?
yield self
elsif respond_to?(method)
__send__(method, *args, &block)
else
nil
end
end
end
class NilClass
# Calling +try_method+ on +nil+ always returns +nil+.
# It becomes specially helpful when navigating through associations that may return +nil+.
#
# === Examples
#
# nil.try_method(:name) # => nil
#
# Without +try_method+
# @person && @person.respond_to(:children) && !@person.children.blank? && @person.children.respond_to(:first) && @person.children.first.respond_to(:name) && @person.children.first.name
#
# With +try_method+
# @person.try_method(:children).try_method(:first).try_method(:name)
def try_method(*args)
nil
end
end