[pypy-dev] Re: [pypy-svn] r8078 - pypy/trunk/src/pypy/interpreter

Christian Tismer tismer at stackless.com
Sun Jan 9 23:21:42 CET 2005

Armin Rigo wrote:

> Hi,
> On Fri, Jan 07, 2005 at 12:39:41PM +0100, holger krekel wrote:
>>>changed LOAD_GLOBAL to support the flow space better.
>>>In case of a NameError, where the space does not define NameError,
>>>we raise a real NameError with a message.
>>(...).  It seems the flow
>>object space could easily provide its own w_NameError and
>>then you can check the usual way, catching an OperationError and 
>>then for e.match(space, space.w_NameError) without changing 
>>the interpreter. 

No, I tried that in the last sprint, but Armin hit my
fingers and said "no no, we *want* to crash here!",
which is correct. So I thought to crash with a useful
message, instead.

> I guess the goal is to have the problem crash the program with a meaningful
> error message.  If the flow objspace provided a w_NameError, then it would
> become a normal exception within the flow graph, and you would end up
> compiling a program that contains an explicit "raise NameError".  In this case
> it's better just to crash the flow objspace clearly.

Exactly. An errorof this kind is usually a bug in the
source code, and actually I found one in _formatting.

> Maybe a nicer hack than Christian's can be found for this purpose, e.g.  
> setting w_NameError to a special value that would trigger an (interp-level)  
> AssertionError in the constructor of OperationError -- the advantage is that
> the AssertionError can provide the meaningful bit of information: the intended
> message of the faulty w_NameError.

Sure, there are better ways.
For me, having the real name error instead of a simple
crash was extremely helpful, because I finally wanted
to get that translation out of the door. :-)
But don't allow a NameError, because that is a violation
of the flow space's contract: Global names are constants
and must exist.

ciao - chris

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