[Python-bugs-list] [ python-Bugs-701135 ] except: grammar is incorrect

[SourceForge.net]

Bugs item #701135, was opened at 2003-03-10 21:15
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=701135&group_id=5470

Category: Documentation
Group: None
>Status: Closed
>Resolution: Invalid
Priority: 5
Submitted By: Mark Ferris (mferris1)
>Assigned to: Michael Hudson (mwh)
Summary: except: grammar is incorrect

Initial Comment:
In the Python Language Reference manual, it shows the try-
except grammar as:
try_exc_stmt::= "try" ":" 
suite
("except" [expression ["," target]] ":" 
suite)+

This implies that this is a valid except 
stanza:
except TypeError or VaueError or 
KeyError:

This syntax does not produce any errors, but it 
doesn't work as one would expect either.  It only "excepts" the first 
exception in the expression; i.e. TypeError in this 
example.

I am assuming the grammar doc just needs to be 
updated and this is not the intented syntax for except.


----------------------------------------------------------------------

>Comment By: Michael Hudson (mwh)
Date: 2003-03-11 10:37

Message:
Logged In: YES 
user_id=6656

No, the grammar is correct.

>>> TypeError or VaueError or KeyError 
<class exceptions.TypeError at 0x8106504>

It may not be what you expected, but it's what's allowed:

/>> def e():
|..     import random
|..     return random.choice([KeyError, TypeError])
\__ 
/>> def f():
|..     try:
|..         {}[2]
|..     except e():
|..         print "caught 1"
|..     except:
|..         print "caught 2"
\__ 
->> f()
caught 1
->> f()
caught 1
->> f()
caught 2
->> f()
caught 2
->> f()
caught 1
->> 

... and so on.


----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=701135&group_id=5470