Re: [Help-smalltalk] Correct way to throw exceptions/errors from C to ST

[Paolo Bonzini]

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On 07/04/2015 18:24, Roland Plüss wrote:
> 
> 
> On 04/06/2015 06:45 PM, Holger Hans Peter Freyther wrote:
>> On Sun, Apr 05, 2015 at 05:47:29PM +0200, Roland Plüss wrote:
>> 
>>> What you mean with "C-style error"? A C++ exception (that
>>> doesn't work it looks like)? The cCall is of void return type
>>> so I can't return anything. And smalltalk side can't check the
>>> arguments as the information required to perform the checks is
>>> sometimes located deep inside the engine code base.
>> "C-style" error.. a non zero return code and maybe setting a 
>> variable with the semantic of errno. The return type of "void" is
>> your decision? Can't you return something to indicate success or
>> failure?
> I sure can decide the return type. I just considered it quite quick
> and easy if I could return an #int if I link to a function
> actually returning an integer. I certainly could return nil but
> then I have no idea what error really happened nor can I properly
> catch it (well... besides ifNotNil: ). Since Smalltalk has already
> an exception/error system why not using it? I don't like wrangling
> a language unless there's no other choice.

You can return an exception object and throw it from Smalltalk.  It
certainly can work with methods that would return #void (return nil if
there is no exception), it is a bit more complicated for methods that
could either return a value or throw an exception.

Paolo

> 
> And as far as I know I can't include any code into a <primitive> 
> declared method.
> 
> I once did the trick with errno type error handling in a module I
> made for Smalltalk but it's cumbersome to use and error prone.
> 
> 
> 
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> 
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