x = StandardError.new(:hello) y = StandardError.new(:hello) x == y # => true x === y # => true begin raise x rescue x puts "ok" # gets printed end begin raise x rescue y puts "ok" # doesn't get printed end
为什么不打印第二个“ok”？我无法弄清楚.我已经读过here,ruby使用===运算符来匹配rescue子句的异常,但表面上并非如此.
我正在使用Ruby 1.9.3
编辑：所以看起来像是在提升x之后,x == y和x === y不再持有.似乎是因为x和y no longer have the same backtrace.
解决方法
我只想在表格中添加一些东西：OP代码表明两个例外是相同的但它们不是 – 而且我想说明OP的意思：
So it seems like that after doing raise x,x == y and x === y no longer hold. It seems to because x and y no longer have the same backtrace.
x = StandardError.new(:hello)
y = StandardError.new(:hello)
class Object
def all_equals(o)
ops = [:==,:===,:eql?,:equal?]
Hash[ops.map(&:to_s).zip(ops.map {|s| send(s,o) })]
end
end
puts x.all_equals y # => {"=="=>true,"==="=>true,"eql?"=>false,"equal?"=>false}
begin
raise x
rescue
puts "ok" # gets printed
end
puts x.all_equals y # => {"=="=>false,"==="=>false,"equal?"=>false}