D - bit expression is not a boolean ??

Mike Wynn (15/15) Aug 20 2003 is this a compiler bug ? v0.69 win32

Walter (5/20) Aug 20 2003 This is not about bit types, but more about disallowing '=' as the opera...

Derek Parnell (12/36) Aug 20 2003 Or maybe ..

Mike Wynn (5/41) Aug 21 2003 able

Philippe Mori (12/52) Aug 21 2003 Maybe we should extend if (and also while) such to allows the

Derek Parnell (11/66) Aug 21 2003 Possibly, but I was thinking more along the lines of this ...
Mike Wynn (9/62) Aug 21 2003 i've
Matthew Wilson (11/23) Aug 29 2003 This is the ugly C++ workaround, but not good enough for D, methinks.

Walter (6/31) Sep 12 2003 Nope.

"Mike Wynn" <mike.wynn l8night.co.uk> writes:

is this a compiler bug ? v0.69 win32

int main( char[][] args ) {
 bit dostuff;
 if ( dostuff = (args.length > 2) ) {
  return 0;
 }
 return 1;
}

//bit_test.d(4): '=' does not give a boolean result

after all the bit is bool postings etc, I would have expected to be able to
write the above code
and not
 if ( (dostuff = (args.length > 2)) == true ) {
  return 0;
 }

Aug 20 2003

"Walter" <walter digitalmars.com> writes:

This is not about bit types, but more about disallowing '=' as the operator
for a boolean test, due to it being usually a typo for '=='.


"Mike Wynn" <mike.wynn l8night.co.uk> wrote in message
news:bi1me1$1n9p$1 digitaldaemon.com...
 is this a compiler bug ? v0.69 win32

 int main( char[][] args ) {
  bit dostuff;
  if ( dostuff = (args.length > 2) ) {
   return 0;
  }
  return 1;
 }

 //bit_test.d(4): '=' does not give a boolean result

 after all the bit is bool postings etc, I would have expected to be able

to
 write the above code
 and not
  if ( (dostuff = (args.length > 2)) == true ) {
   return 0;
  }

Aug 20 2003

Derek Parnell <derek.parnell no.spam> writes:

On Wed, 20 Aug 2003 23:21:09 -0700 (08/21/03 16:21:09)
, Walter <walter digitalmars.com> wrote:

 This is not about bit types, but more about disallowing '=' as the 
 operator
 for a boolean test, due to it being usually a typo for '=='.


 "Mike Wynn" <mike.wynn l8night.co.uk> wrote in message
 news:bi1me1$1n9p$1 digitaldaemon.com...
 is this a compiler bug ? v0.69 win32

 int main( char[][] args ) {
 bit dostuff;
 if ( dostuff = (args.length > 2) ) {
 return 0;
 }
 return 1;
 }

 //bit_test.d(4): '=' does not give a boolean result

 after all the bit is bool postings etc, I would have expected to be able

 to
 write the above code
 and not
 if ( (dostuff = (args.length > 2)) == true ) {
 return 0;
 }


Or maybe ..

  int main( char[][] args ) {
  bit dostuff;
  if ( dostuff = (args.length > 2), dostuff ) {
    return 0;
  }
  return 1;
  }


-- 
Derek

Aug 20 2003

"Mike Wynn" <mike.wynn l8night.co.uk> writes:

"Derek Parnell" <derek.parnell no.spam> wrote in message
news:oprt8s4jv759ej19 news.digitalmars.com...
 On Wed, 20 Aug 2003 23:21:09 -0700 (08/21/03 16:21:09)
 , Walter <walter digitalmars.com> wrote:

 This is not about bit types, but more about disallowing '=' as the
 operator
 for a boolean test, due to it being usually a typo for '=='.


 "Mike Wynn" <mike.wynn l8night.co.uk> wrote in message
 news:bi1me1$1n9p$1 digitaldaemon.com...
 is this a compiler bug ? v0.69 win32

 int main( char[][] args ) {
 bit dostuff;
 if ( dostuff = (args.length > 2) ) {
 return 0;
 }
 return 1;
 }

 //bit_test.d(4): '=' does not give a boolean result

 after all the bit is bool postings etc, I would have expected to be



able
 to
 write the above code
 and not
 if ( (dostuff = (args.length > 2)) == true ) {
 return 0;
 }


 Or maybe ..

   int main( char[][] args ) {
   bit dostuff;
   if ( dostuff = (args.length > 2), dostuff ) {
     return 0;
   }
   return 1;
   }

I personally hate that form, like that it does not look too bad, but i've
seen some "wonderful" uses of comma operator in if's in the past.

Aug 21 2003

"Philippe Mori" <philippe_mori hotmail.com> writes:

 This is not about bit types, but more about disallowing '=' as the
 operator
 for a boolean test, due to it being usually a typo for '=='.


 "Mike Wynn" <mike.wynn l8night.co.uk> wrote in message
 news:bi1me1$1n9p$1 digitaldaemon.com...
 is this a compiler bug ? v0.69 win32

 int main( char[][] args ) {
 bit dostuff;
 if ( dostuff = (args.length > 2) ) {
 return 0;
 }
 return 1;
 }

 //bit_test.d(4): '=' does not give a boolean result

 after all the bit is bool postings etc, I would have expected to be



 able
 to
 write the above code
 and not
 if ( (dostuff = (args.length > 2)) == true ) {
 return 0;
 }


 Or maybe ..

   int main( char[][] args ) {
   bit dostuff;
   if ( dostuff = (args.length > 2), dostuff ) {
     return 0;
   }
   return 1;
   }

 I personally hate that form, like that it does not look too bad, but i've
 seen some "wonderful" uses of comma operator in if's in the past.

Maybe we should extend if (and also while) such to allows the
following syntax (similar to for):

if (declaration; condition)
{
}

Otherwise yo can always do

{
    declarations;
    if (condition)
    {
    }
}

Aug 21 2003

Derek Parnell <derek.parnell no.spam> writes:

On Thu, 21 Aug 2003 10:01:43 -0400 (08/22/03 00:01:43)
, Philippe Mori <philippe_mori hotmail.com> wrote:

 This is not about bit types, but more about disallowing '=' as the
 operator
 for a boolean test, due to it being usually a typo for '=='.


 "Mike Wynn" <mike.wynn l8night.co.uk> wrote in message
 news:bi1me1$1n9p$1 digitaldaemon.com...
 is this a compiler bug ? v0.69 win32

 int main( char[][] args ) {
 bit dostuff;
 if ( dostuff = (args.length > 2) ) {
 return 0;
 }
 return 1;
 }

 //bit_test.d(4): '=' does not give a boolean result

 after all the bit is bool postings etc, I would have expected to be



 able
 to
 write the above code
 and not
 if ( (dostuff = (args.length > 2)) == true ) {
 return 0;
 }


 Or maybe ..

   int main( char[][] args ) {
   bit dostuff;
   if ( dostuff = (args.length > 2), dostuff ) {
     return 0;
   }
   return 1;
   }

 I personally hate that form, like that it does not look too bad, but 
 i've
 seen some "wonderful" uses of comma operator in if's in the past.

 Maybe we should extend if (and also while) such to allows the
 following syntax (similar to for):

 if (declaration; condition)
 {
 }

 Otherwise yo can always do

 {
 declarations;
 if (condition)
 {
 }
 }

Possibly, but I was thinking more along the lines of this ...

As the form if ( <EXPRESSION> )  is valid then it might be just simple 
enough to do ...

  if ( (a = b) )

in other words, if the assignment expression is enclosed in its own 
parenthesis, it is considered to be a simple single-term expression, which 
does provided a valid boolean result.

-- 
Derek

Aug 21 2003

"Mike Wynn" <mike.wynn l8night.co.uk> writes:

"Philippe Mori" <philippe_mori hotmail.com> wrote in message
news:bi2j25$31bd$1 digitaldaemon.com...
 This is not about bit types, but more about disallowing '=' as the
 operator
 for a boolean test, due to it being usually a typo for '=='.


 "Mike Wynn" <mike.wynn l8night.co.uk> wrote in message
 news:bi1me1$1n9p$1 digitaldaemon.com...
 is this a compiler bug ? v0.69 win32

 int main( char[][] args ) {
 bit dostuff;
 if ( dostuff = (args.length > 2) ) {
 return 0;
 }
 return 1;
 }

 //bit_test.d(4): '=' does not give a boolean result

 after all the bit is bool postings etc, I would have expected to be



 able
 to
 write the above code
 and not
 if ( (dostuff = (args.length > 2)) == true ) {
 return 0;
 }


 Or maybe ..

   int main( char[][] args ) {
   bit dostuff;
   if ( dostuff = (args.length > 2), dostuff ) {
     return 0;
   }
   return 1;
   }

 I personally hate that form, like that it does not look too bad, but


i've
 seen some "wonderful" uses of comma operator in if's in the past.

 Maybe we should extend if (and also while) such to allows the
 following syntax (similar to for):

 if (declaration; condition)
 {
 }

 Otherwise yo can always do

 {
     declarations;
     if (condition)
     {
     }
 }

and how exactly is that better (or different) from
if ( expr, var ) { .... }
and for IS an extended while!

my complaint was if ( bit_assign ) is an error
I agree `if ( object_assign ) ...` or `if ( int_assign ) ...` are not `if
( boolean )` and thus an error (or potential error.

Aug 21 2003

"Matthew Wilson" <matthew stlsoft.org> writes:

 Maybe we should extend if (and also while) such to allows the
 following syntax (similar to for):

 if (declaration; condition)
 {
 }

Wow, I thought it did support this!

It must do.

 Otherwise yo can always do

 {
     declarations;
     if (condition)
     {
     }
 }

This is the ugly C++ workaround, but not good enough for D, methinks.

Another imperfection in C++ is the fact that you can declare variables of
only one type in a for statement.

We would like to be able to do the following in D:

  for(int i = 0, j, k = 0, long l = 0, m, n = 0; ...)
 {

 } // i, j, k, l, m, n all cease to exist here

Walter, does this present any serious problem for the parser? (I'm assuming
it'd be a breeze for a man of your talent.)

Aug 29 2003

"Walter" <walter digitalmars.com> writes:

"Matthew Wilson" <matthew stlsoft.org> wrote in message
news:biojkj$ah0$1 digitaldaemon.com...
 Maybe we should extend if (and also while) such to allows the
 following syntax (similar to for):

 if (declaration; condition)
 {
 }

 Wow, I thought it did support this!

Nope.

 It must do.

Why?

 Otherwise yo can always do

 {
     declarations;
     if (condition)
     {
     }
 }

 This is the ugly C++ workaround, but not good enough for D, methinks.

 Another imperfection in C++ is the fact that you can declare variables of
 only one type in a for statement.

 We would like to be able to do the following in D:

   for(int i = 0, j, k = 0, long l = 0, m, n = 0; ...)
  {

  } // i, j, k, l, m, n all cease to exist here

 Walter, does this present any serious problem for the parser? (I'm

assuming
 it'd be a breeze for a man of your talent.)

There are some ambiguity problems using typedef'd names after the ,.

Sep 12 2003

D Programming

C/C++ Programming

Other

D - bit expression is not a boolean ??