Contract programming syntax

[Denis Koroskin]

On Thu, 09 Apr 2009 00:51:49 +0400, Christopher Wright <dhasenan at gmail.com> wrote:

> bearophile wrote:
>> But isn't a syntax like the following better? To me it looks more  
>> logic, because in{} and out(){} are part of the function, and there's  
>> no need of a special syntax for the body (and the 'body' keyword):
>>  long squareRoot(long x) {
>>     in {
>>         assert(x >= 0);
>>     }
>>      out (result) {
>>         assert((result * result) <= x && (result+1) * (result+1) >= x);
>>     }
>>      return cast(long)std.math.sqrt(cast(real)x);
>> }
>
> No. This proposed syntax change is quite misleading. Contracts cannot  
> access the function's local variables, but it looks like they can.  
> Contracts are executed at particular times, but that syntax makes them  
> look like they execute wherever they are written.
>
> I believe you can put "body" before each function body, even with no  
> contracts, if it makes you happier.
>
>> Bye,
>> bearophile

Does scope(exit) also make you feel that it is executed immediately?

I see nothing wrong with local variables to be available in "out", but in most cases "out" is defined /before/ function body so no variables will be visible this way.

It also looks like you can have multiple in{} and out{} sections this way. This is a nice bonus, btw!