github.com/Bytom/bytom@v1.1.2-0.20210127130405-ae40204c0b09/errors/doc.go (about)

     1  /*
     2  Package errors implements a basic error wrapping pattern, so that errors can be
     3  annotated with additional information without losing the original error.
     4  
     5  Example:
     6  
     7  	import "chain/errors"
     8  
     9  	func query() error {
    10  		err := pq.Exec("SELECT...")
    11  		if err != nil {
    12  			return errors.Wrap(err, "select query failed")
    13  		}
    14  
    15  		err = pq.Exec("INSERT...")
    16  		if err != nil {
    17  			return errors.Wrap(err, "insert query failed")
    18  		}
    19  
    20  		return nil
    21  	}
    22  
    23  	func main() {
    24  		err := query()
    25  		if _, ok := errors.Root(err).(sql.ErrNoRows); ok {
    26  			log.Println("There were no results")
    27  			return
    28  		} else if err != nil {
    29  			log.Println(err)
    30  			return
    31  		}
    32  
    33  		log.Println("success")
    34  	}
    35  
    36  When to wrap errors
    37  
    38  Errors should be wrapped with additional messages when the context is ambiguous.
    39  This includes when the error could arise in multiple locations in the same
    40  function, when the error is very common and likely to appear at different points
    41  in the call tree (e.g., JSON serialization errors), or when you need specific
    42  parameters alongside the original error message.
    43  
    44  Error handling best practices
    45  
    46  Errors are part of a function's interface. If you expect the caller to perform
    47  conditional error handling, you should document the errors returned by your
    48  function in a function comment, and include it as part of your unit tests.
    49  
    50  Be disciplined about validating user input. Programs should draw a very clear
    51  distinction between user errors and internal errors.
    52  
    53  Avoid redundant error logging. If you return an error, assume it will be logged
    54  higher up the call stack. For a given project, choose an appropriate layer to
    55  handle error logging.
    56  */
    57  package errors