使用Go的日志包以默认格式设置PANIC

Question

When logging in Go with log.Println, I frequently get

2012/05/13 16:45:50 evaluating %v(PANIC=3)

I'm not sure how to determine what I've done wrong, I assume that somewhere fmt.Println has caught a panic generated by one of my own Stringer interface implementations, so as not to crash my program due to logging failure.

How do I work out what's going on? Why am I getting this erroneous message?

Answer 1

You are right, there is a panic in a String method. But it has nothing to do with the log package. Println uses %v, and %v means running String method. Having a panic in the String method invokes catchPanic. Here in your output 3 is the value of your panic.