Ruby on Rails latest stable (v4.0.2) - 5 notes - Class: Object
try(*a, &b) public

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


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|

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|

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.

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January 6, 2010
6 thanks

Doesn't return nil if the object you try from isn't nil.

Note that this doesn’t prevent a NoMethodError if you attempt to call a method that doesn’t exist on a valid object.

a = Article.new

a.try(:author) #=> #<Author ...>

nil.try(:doesnt_exist) #=> nil

a.try(:doesnt_exist) #=> NoMethodError: undefined method `doesnt_exist' for #<Article:0x106c7d5d8>

This is on Ruby 1.8.7 patchlevel 174

June 10, 2009
2 thanks

[:a, :b, :c].try([1]) ? The answer is No.

Correct way is this:

[:a, :b, :c].try(:at, 1)
July 24, 2012
2 thanks

rest of code is in NilClass#try

If you click “Show source” here, you may get confused. The logic for #try is shared between this method and NilClass#try . Both versions are currently implemented in the file activesupport/lib/active_support/core_ext/object/try.rb .

January 6, 2010
0 thanks


without using at

[:a, :b, :c].try(:[], 1)
September 13, 2013
0 thanks

Edge case

NilClass#try doesn’t check for methods on itself:

nil.blank?        #=> true
nil.try :blank?   #=> nil