Re: [Reuseware-devel] type casting in composition programs

[Sven K. <s78...@in...>]

Hello again!

We could do something which compares attribute types of two fragment 
types to determine if a cast is possible. And if the attributes are 
compatible we could create a new fragment of the type to which  we want 
to cast having the same values as the old fragment. But this is in fact 
not casting, it is more like cloning or converting, since casting (in 
the classical java sence) allways threats one object/fragment which 
might be referenced by different variables/fragmentlists.

 >However, I'm guessing that this situation will appear in other scenarios
 >in the future as well. So, the question is what we should do.

It happend allready to me, but I thought the string concatenation was 
the way to go because it was implemented and used in some examples.

Sven.




Jakob Henriksson schrieb:
> Hi,
>
> They might not be type compatible, I'm not really sure. What I'm sure  
> about is that I want a solution which doesn't step outside the type system  
> (which is currently the case). Maybe a solution for Modular Xcerpt is  
> possible to find, by using different types from Xcerpt, not to use  
> componentmodel.Location etc. I don't know exactly in this very moment how  
> it can be solved, but probably somehow.
>
> However, I'm guessing that this situation will appear in other scenarios  
> in the future as well. So, the question is what we should do.
>
> Going back to the example. What I want to bind is a QuotedString (i.e. the  
> slot). What I have is a Location. The value of a location is a string. If  
> you define a QuotedString to be:
>
> QuotedString	=	"\"" value:S "\"";
>
> (or something to that effect), then the values of Location and  
> QuotedString are really the same. Here, the '"'s are really just concrete  
> syntax, aren't they? Somehow it seems that the values from the different  
> types in this case can be cast to each other (it might not always be  
> possible, but in this case it is, which is why we could successfully  
> employ a cast).
>
> Anyway, discussion will hopefully continue.
>
> Please CC "Reuseware Developer"  
> <reu...@li...> on all mailing discussions so  
> that everybody can follow the discussions and so that it will end up in  
> the mailing list archives later on. It will be interesting to have. It  
> also shows some activity to the outside world ;)
>
> Cheers,
> Jakob
>
>
> On Fri, 07 Sep 2007 17:37:20 +0200, Sven Karol  
> <s78...@in...> wrote:
>
>   
>> Hi!
>>
>> I really dont know if a simple cast would be the right solution here,  
>> since "componentmodel.Location" and  "xcerpt.QuotedString" are not type  
>> compatible (aren't they?). Because of that, you really need  that  
>> information  about concrete syntax as it is used by the string  
>> concatenation,  so something like
>>
>>     > bind moduleID on qtWrapper with  
>> (xcerpt.QuotedString)'"'moduleID'"'.mxcerpt;
>>
>> is possible to be implemented. If we really want to have
>>
>>     > bind moduleID on qtWrapper with (xcerpt.QuotedString)moduleID;
>>
>> reuseware would have to check all concrete Syntaxes registered as  
>> parser/printer for "xcerpt.QuotedString" for prefixes and suffixes ('"'  
>> and '"' in the case of mxcerpt) and do the string concatenation  
>> internally. Of course this would work in some very special cases only  
>> and has no clear semantics to the user. Additionally I currently do not  
>> know if the concrete Syntax is accessible as far as one would need for  
>> implementation of that feature, but I guess not.
>>
>>
>> greetz,
>>     Sven.
>>     
>
>
>
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