Re: What c.l.py's opinions about Soft Exception?

On 9 Mrz., 09:30, Lie <Lie.1...@xxxxxxxxx> wrote:
On Mar 9, 12:05 pm, Kay Schluehr <kay.schlu...@xxxxxxx> wrote:

On 9 Mrz., 04:51, Lie <Lie.1...@xxxxxxxxx> wrote:

A more through implementation would start from the raiser inspecting
the execution stack and finding whether there are any try block above
it, if no try block exist it pass silently and if one exist it will
check whether it have a matching except clause. This also circumvents
a problem that simple implementation have, as described below.

This will not be easy in particular in the presence of inheritance and
dynamism. There is no way to statically decide whether an exception
BException has the type AException and will be caught by the except
clause in

try:
BLOCK
except AException, e:
print "SoftException %s caught"%e
A feasible solution was to invert the try...except statement and
creating a continuation.

catch AException, a:
print "SoftException A: %s"%a
catch BException , b:
print "SoftException B: %s"%b
...
in:
BLOCK

Here each SoftException is raised initially when a catch clause is
entered and a continuation is created that returns to the catch block
of the raised SoftException if required. When a SoftException is
raised within BLOCK a lookup will be made and if a corresponding
SoftException was found that was raised by a catch-clause the current
control flow will be suspended and the continuation is called.

I'd rather want to avoid any syntax changes, as I wished that Soft
Exception can be added to the language silently[1] so that new
programmers doesn't _need_ to know about it (although knowing it could
change the way they write codes to be more structured and simple).

I just tried to save your proposal from being unimplementable. Maybe
you can comment on it?

I know of course that syntax is Pythons holy cow but I'm not Guidos
mouthpiece and have a different perspective on some aspects of the
system for obvious reasons [1]. I appreciate when people in the Python
community talk about what is useful for them and not what the
imaginary Pythonista superego thinks about them and how it will be
standardized in the end - if anyhow.

I'd like to know if SoftExceptions would make programs more reliable
in the end because people won't use them sparingly but for all kinds
of events that are somewhat "irregular" ( i.e. warnings ) not just for
obvious errors. It's an interesting idea to have an advanced warning
system that is more responsive than just this kind of logging which is
currently implemented. And I'd surely discriminate them from the
current exception handling at least in the design phase. Later
language changes could still be "dissolved".

[1] http://www.fiber-space.de/EasyExtend/doc/EE.html

.

Relevant Pages

  • Re: What c.l.pys opinions about Soft Exception?
    ... entered and a continuation is created that returns to the catch block ... of the raised SoftException if required. ... current syntax could be used, we could just use it (except if there is ... a strong reason why it shouldn't be done). ...
    (comp.lang.python)
  • Re: What c.l.pys opinions about Soft Exception?
    ... print "SoftException %s caught"%e ... entered and a continuation is created that returns to the catch block ... Exception can be added to the language silentlyso that new ... You can't inspect the call stack for this ...
    (comp.lang.python)
  • Re: What c.l.pys opinions about Soft Exception?
    ... check whether it have a matching except clause. ... BException has the type AException and will be caught by the except ... print "SoftException %s caught"%e ... entered and a continuation is created that returns to the catch block ...
    (comp.lang.python)