ruby的异常处理和java很相似
begin
...
rescue
...
end
rescue默认只会接受StandardError
irb(main):001:0> begin
irb(main):002:1* 1 / 0
irb(main):003:1> rescue
irb(main):004:1> puts "divide 0"
irb(main):005:1> end
divide 0
但是像SyntaxError并不是继承StandardError的，就无法被resuce
irb(main):001:0> begin
irb(main):002:1* eval("1 +")
irb(main):003:1> rescue
irb(main):004:1> puts "syntax error"
irb(main):005:1> end
SyntaxError: (eval):1:in `irb_binding': compile error
(eval):1: syntax error, unexpected $end
from (irb):2
from (irb):2
from :0
这种情况必须指定相应的Error或者是所有异常的基类Exception
irb(main):001:0> begin
irb(main):002:1* eval("1 +")
irb(main):003:1> rescue Exception
irb(main):004:1> puts "syntax error"
irb(main):005:1> end
syntax error
最后附上Exception Hierarchy
Exception
NoMemoryError
ScriptError
LoadError
NotImplementedError
SyntaxError
SignalException
Interrupt
StandardError
ArgumentError
IOError
EOFError
IndexError
LocalJumpError
NameError
NoMethodError
RangeError
FloatDomainError
RegexpError
RuntimeError
SecurityError
SystemCallError
SystemStackError
ThreadError
TypeError
ZeroDivisionError
SystemExit
fatal
