Ruby Error Handling and exceptions

I. Common anomalies

Exception name	Common causes	How to Throw
RuntimeError	Default exception thrown by raise	Raise
Nomethoderror	Object cannot find a corresponding method	A=oject.new A.jackmethod
Nameerror	The interpreter encounters an identifier that cannot be resolved to a variable or method name	A=jack
IOError	Reads a closed stream, writes a read-only stream, or a similar operation	Stdin.puts ("Cannot write")
Errno::error	A class of errors related to file IO	File.Open (-10)
TypeError	Method accepts a parameter that it cannot handle	a=3+ "ABC"
Argumenterror	Error passing the number of parameters	def o (x) End O (All-you-do)

Second, catch the exceptioncatching exceptions with rescue#用rescue捕获异常beginResult=20/0puts resultRescueZerodivisionerrorputs "Zero Error"RescuePuts "Unknow error"EndOutput: Zero Error three,raise throws an exceptiondef divide (x) Raise Argumenterror if X==0end begindivide (0) Rescue argumenterrorputs "Argumenterror" End output: Argumenterror Iv. Save the exception to the variable def divide (x) Raise Argumenterror if X==0end begindivide (0)Rescue =>ePuts E.to_send output: Argumenterror v. Create exception classthrowexceptionl<exceptionPuts "error L" End Beginraise throwexceptionl, "Got error" rescue throwexceptionl=>eputs "error #{e}" End output: Error lerror Got error

Sample Ruby exception handling structure code:

1. Begin #开始
2. Raise. #抛出异常
3. Rescue [Exceptiontype =
   Standardexception]
   #捕获指定类型的异常 Default value is Standardexception
4. $! #表示异常信息
5. [Email protected] #表示异常出现的代码位置
6. else #其余异常
7. ..
8. Ensure #不管有没有异常, enter the code block
9. End #结束

Can be combined with $! error causes, and [email protected] Error location to do a bug capture and prompt the small program, such as:

1. Begin
2. Puts
3. Puts "file: #{name = argv.shift}"
4. File = open (name)
5. i = 0
6. File.read.each_line
   {|line| puts "#{i+=1}.#{line}"}
7. Rescue
8. Puts "error:#{$!} At:#{[email protected]} "
9. Ensure
10. File.close
11. End

Ruby Error Handling and exceptions