dhansen@btree.com (Dave Hansen) wrote:

>  If you have a bunch of these in
>existing code, it's tedious but not unreasonable (IMHO :) to fix any
>such assignment by inserting the apporpriate cast.

What about library code? A third-party library may very well use int for
bool because bool was not available. Third-party libraries are difficult
to patch because patches will have to re-applied every time a newer
version of the library becomes available. Also, the library might be on
CD-ROM. Even forgetting about 3rd party libraries, modifying a million
lines of code before a new compiler can be installed can sap a project
of more than one day of productivity. In the real-world of business, it
is, IMHO NOT reasable to force casts to be introduced into
previously-working code.

-------------------------------------------------------------
Pablo Halpern                   phalpern@truffle.ultranet.com

I am self-employed. Therefore, my opinions *do* represent
those of my employer.


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On 19 Sep 1996 10:32:55 PDT, Andrew Koenig wrote in comp.std.c++:


>An example of what breaks:

> int flag;
> flag = x > y;

>If the language is changed so that x > y is bool, rather than int,
>then it had better be possible to convert bool to int.

What I had suggested was that such conversions no longer be implicit.
The conversion would still be possible, but you must make the
conversion explicit in the source.  If you have a bunch of these in
existing code, it's tedious but not unreasonable (IMHO :) to fix any
such assignment by inserting the apporpriate cast.

Is this the issue?  That is, would a change of this sort be rejected
because it would require existing code to be modified in such a benign
way?

In the example above, what are you really trying to say?  IMHO, given
only this snippet, I would say flag should be a bool rather than an
int.  This more closely reflects the semantics of the variable.  I see
how flag is set.  How is it used?

Best Regards.

     -=Dave
     dhansen@btree.com

I can barely speak for myself, so I certainly can't speak for B-Tree



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Dave Hansen (dhansen@btree.com) wrote:
[Looking for an example where boolean types are used as ints.]

int count_inversions(int sample[], size_t count) {
 int inversions = 0;

 for (int index = 1; index < count; index++)
  inversions += sample[index - 1] > sample[index];

 return inversions;
}

Getting rid of the implicit conversion would break a fair bit of code and
while it might not be too painful to fix on an individual basis, its a lot
of pain when totaled up.

-Z-


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In article <199609192019.PAA05859@T-Rex.Minn.Net> dhansen@btree.com writes:

> > int flag;
> > flag = x > y;

> >If the language is changed so that x > y is bool, rather than int,
> >then it had better be possible to convert bool to int.

> What I had suggested was that such conversions no longer be implicit.
> The conversion would still be possible, but you must make the
> conversion explicit in the source.  If you have a bunch of these in
> existing code, it's tedious but not unreasonable (IMHO :) to fix any
> such assignment by inserting the apporpriate cast.

> Is this the issue?  That is, would a change of this sort be rejected
> because it would require existing code to be modified in such a benign
> way?

Exactly.  The committee was given the option to allow the conversion or
not, and voted to allow it (by roughly a 2-1 margin, if I remember right).


--
    --Andrew Koenig
      ark@research.att.com


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