From dc03983c28af0625dea7b35dbb7f34967e95dc1f Mon Sep 17 00:00:00 2001 From: Mark Pilgrim Date: Tue, 4 Aug 2009 20:09:54 -0700 Subject: [PATCH] typography fiddling --- your-first-python-program.html | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/your-first-python-program.html b/your-first-python-program.html index e929da7..2997927 100755 --- a/your-first-python-program.html +++ b/your-first-python-program.html @@ -275,7 +275,7 @@ SyntaxError: non-keyword arg after keyword arg 
if size < 0:
     raise ValueError('number must be non-negative')
-

The syntax for raising an exception is simple enough. Use the raise statement, followed by the exception name, and an optional human-readable string for debugging purposes. The syntax is reminiscent of calling a function. (In reality, exceptions are implemented as classes, and this raise statement is actually creating an instance of the ValueError class and passing the string 'number must be non-negative' to its initialization method. But we’re getting ahead of ourselves ! ) +

The syntax for raising an exception is simple enough. Use the raise statement, followed by the exception name, and an optional human-readable string for debugging purposes. The syntax is reminiscent of calling a function. (In reality, exceptions are implemented as classes, and this raise statement is actually creating an instance of the ValueError class and passing the string 'number must be non-negative' to its initialization method. But we’re getting ahead of ourselves!)

☞You don’t need to handle an exception in the function that raises it. If one function doesn’t handle it, the exception is passed to the calling function, then that function’s calling function, and so on “up the stack.” If the exception is never handled, your program will crash, Python will print a “traceback” to standard error, and that’s the end of that. Again, maybe that’s what you want; it depends on what your program does.