er在这里代表什么？

Question

try: 
    os.execvp('sqlite3', args) 
except OSError, er: 
    if er.errno == 2: #file not found 
        raise OSError, _("sqlite3 executable not found. Is it installed?") 
    else: 
        raise 
except: 
    raise 

In the above code, the except statement catches the OSError but what does the er variable stand for?

EDIT: this one only excepts OSError ; is there a way to except any error and get the exception object for it?

Answer 1

As others have said, er is the instantiated form of the exception, OSError .

If it's helpful, here's an alternative, somewhat more explicit syntax, using the as keyword:

try: 
    os.execvp('sqlite3', args) 
except OSError as er: 
    if er.errno == 2: #file not found 
        raise OSError(_("sqlite3 executable not found. Is it installed?"))
    else: 
        raise 
except: 
        raise 

Which, to me, says that er will be an OSError .

As as er syntax was added in Python 2.6, by the way.

Answer 2

er是被except子句捕获的实际异常对象。

Answer 3

er是异常对象本身。

Answer 4

看起来er是一个异常对象（OSError类型也看起来包含错误。ER可能代表错误。