[PRL] Contracts vs aspects

[Matthias Felleisen]

Correct. And as I found out, there are a number of such pieces of work,  
and some have been published already. -- Matthias


On Apr 29, 2005, at 12:45 PM, Pengcheng Wu wrote:

>
> On Thu, 28 Apr 2005, Mitchell Wand wrote:
>
>> Adrian Collyer writes (at
>> http://www.aspectprogrammer.org/blogs/adrian/2005/04/ 
>> aspects_as_auto.html):
>>
>>  We'll need a requirement to work from. Let's take good old
>>  foobar. Everyone knows that foo comes before bar. What if we wanted
>>  to write an aspect to make sure that was true? More precisely, let's
>>  write an aspect to enforce the following rule:
>>
>>     Every call to bar() within an action must be preceded by at least
>>     one call to foo(). After any call to bar(), foo() must be called
>>     at least once before bar() can be called again.
>
> Seems to me that Collyer's solution is much less elegant than the trace
> matching solution by Oege de Moor et al, which is very declarative and
> doesn't put the burden of state maintenance on the programmers' side.
>
> They have a tech. report at:
>
>  http://abc.comlab.ox.ac.uk/documents/abc-2005-1.pdf
>
> Using their approach, I could come up with an aspect checker of the  
> above
> rules as easy as the following (I didn't actually run it):
>
> tracematch() {
>   sym notfoocall after: call(!foo(..));
>   sym foocall after: call(foo(..));
>   sym barcall before: call(bar(..));
>   sym barcallafter after: call(bar(..));
>
>   notfoocall* barcall {
>      error("bar without foo");//rule 1 violation
>   }
>
>   barcallafter notfoocall* barcall {
>      error("bar calls without foo in the middle");//rule 2 violation
>   }
> }
>
> Their compiler will generate the corresponding state transition code.
>
> --Pengcheng
>
>
>
>
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