HDC调试需求开发（15万预算）,能者速来！>>>

刚刚看到 @moli 写的代码，get 到 try 方法很好用。于是顺便贴一下其 API
try(*a, &b)
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 .name if@person
try calls can be chained:
@person .try( :spouse ).try( :name )
instead of
@person .spouse.name if@person && @person .spouse
try will also return nil if the receiver does not respond to the method:
@person .try( :non_existing_method ) # => nil
instead of
@person .non_existing_method if@person .respond_to?( :non_existing_method ) # => 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 in case of argument mismatch.
If try is called without arguments it yields the receiver to a given block unless it is nil :
@person .try do|p|
...
end
You can also call try with a block without accepting an argument, and the block will be instance_eval'ed instead:
@person .try { upcase.truncate( 50 ) }
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 .