• bearophile (5/5) Oct 09 2010 A possible enhancement for Contract Programming:
• Tomek =?UTF-8?B?U293acWEc2tp?= (12/13) Oct 09 2010 by the class invariant.
• bearophile (12/22) Oct 09 2010 D2 has several ways to perform conditional compilation, so you may imple...
• bearophile (3/4) Oct 09 2010 Sorry, I meant, 'And ghost fields aren't very important to start with'.
• Tomek =?UTF-8?B?U293acWEc2tp?= (6/43) Oct 09 2010 OK, thx for explanation. But as you said, ghost fields aren't that impor...
• Denis Koroskin (4/16) Oct 09 2010 =

bearophile <bearophileHUGS lycos.com> writes:

A possible enhancement for Contract Programming:
http://d.puremagic.com/issues/show_bug.cgi?id=5027

This is not meant as a replacement for "old" (that allows to refer to the state
at the entry to the instance method).

Bye,
bearophile

Tomek =?UTF-8?B?U293acWEc2tp?= <just ask.me> writes:

bearophile napisał:

 The ghost fields may be used to store partial computations useful to reduce
the work done 

by the class invariant.

You can do:

class C {
  version(unittest) int temp;
  invariant() {
    // use temp
  }
}

Or am I missing something?

-- 
Tomek

bearophile <bearophileHUGS lycos.com> writes:

Tomek S.:

 You can do:
 
 class C {
   version(unittest) int temp;
   invariant() {
     // use temp
   }
 }
 
 Or am I missing something?

D2 has several ways to perform conditional compilation, so you may implement
hand-made ghost fields using a version(debug). And ghost fields are very
important to start with (I was not sure to submit an enhancement request).

There are two things that maybe you are missing. A field like:

version(unittest) int temp;

gets compiled when you use the -unittest, and gets removed otherwise. While the
presence of ghost fields is determined by the presence of active contracts,
that currently are run with the code is compiled in non-release build (so they
are not related to the -unittest switch).

The second problem is that inside a method foo() of that class C you may write:

    void foo() {
        version(unittest) temp++;
    }

But well implemented ghost fields are never visible inside the body of methods.
So if you try to use them inside foo() the compiler has to raise a compile
error.

Bye,
bearophile

bearophile <bearophileHUGS lycos.com> writes:

 And ghost fields are very important to start with (I was not sure to submit an
enhancement request).

Sorry, I meant, 'And ghost fields aren't very important to start with'.

Bye,
bearophile

Tomek =?UTF-8?B?U293acWEc2tp?= <just ask.me> writes:

bearophile napisał:

 Tomek S.:
 
 You can do:
 
 class C {
   version(unittest) int temp;
   invariant() {
     // use temp
   }
 }
 
 Or am I missing something?

 
 D2 has several ways to perform conditional compilation, so you may
 implement hand-made ghost fields using a version(debug). And ghost fields
 are very important to start with (I was not sure to submit an enhancement
 request).
 
 There are two things that maybe you are missing. A field like:
 
 version(unittest) int temp;
 
 gets compiled when you use the -unittest, and gets removed otherwise.
 While the presence of ghost fields is determined by the presence of active
 contracts, that currently are run with the code is compiled in non-release
 build (so they are not related to the -unittest switch).
 
 The second problem is that inside a method foo() of that class C you may
 write:
 
     void foo() {
         version(unittest) temp++;
     }
 
 But well implemented ghost fields are never visible inside the body of
 methods. So if you try to use them inside foo() the compiler has to raise
 a compile error.

OK, thx for explanation. But as you said, ghost fields aren't that important
and conditional 
compilation can provide a crude-but-working implementation, so I doubt the ROI
would be 
positive.

-- 
Tomek

"Denis Koroskin" <2korden gmail.com> writes:

On Sat, 09 Oct 2010 23:51:44 +0400, Tomek Sowi=C5=84ski <just ask.me> wr=
ote:

 bearophile napisa=C5=82:

 The ghost fields may be used to store partial computations useful to =


 =

 reduce the work done

 by the class invariant.

 You can do:

 class C {
   version(unittest) int temp;
   invariant() {
     // use temp
   }
 }

 Or am I missing something?

How often do you *run* your application with unittests enabled?