• John Bell (11/11) Jul 22 2005 I am confused by this in the documentation:
• Stefan (10/21) Jul 23 2005 That's the same as:
• John Bell (7/19) Jul 23 2005 Thanks for the reply. I just thought D worked differently. The
• Manfred Nowak (7/10) Jul 23 2005 [...]

John Bell <jdwbell yahoo.com> writes:

I am confused by this in the documentation:

if (cast(B) o)
{
	// o is an instance of B
}
else
{
	// o is not an instance of B
}

Does this mean that a reference can be implicitly converted to a bool?

Thanks.

Stefan <Stefan_member pathlink.com> writes:

That's the same as:





where "if (ref)" is a shortcut for "if (ref is null)".
It's the same as in C.  if() works with any int, where int == 0 evaluates
to false and any int <> 0 to true. Hope this helps.

Regards,
Stefan


In article <dbsad1$23q7$1 digitaldaemon.com>, John Bell says...
I am confused by this in the documentation:

if (cast(B) o)
{
	// o is an instance of B
}
else
{
	// o is not an instance of B
}

Does this mean that a reference can be implicitly converted to a bool?

Thanks.

John Bell <jdwbell yahoo.com> writes:

Stefan wrote:
 That's the same as:
 



 
 where "if (ref)" is a shortcut for "if (ref is null)".
 It's the same as in C.  if() works with any int, where int == 0 evaluates
 to false and any int <> 0 to true. Hope this helps.
 
 Regards,
 Stefan


Thanks for the reply.  I just thought D worked differently.  The 
documentation states that the expression checked in an if statement must 
be a type that can be converted to a boolean.  And as I understand it a 
bool is a bit.  And I thought that while a bit could be implicitly 
converted to an int, an int could not be implicitly converted to a bit. 
So, the statement had me confused.

Manfred Nowak <svv1999 hotmail.com> writes:

John Bell <jdwbell yahoo.com> wrote:

[...]
 The
 documentation states that the expression checked in an if
 statement must be a type that can be converted to a boolean. 

[...]

You are right and pointers cannot be converted implicitely to 
booleans. Therefore the documentation at least misses to describe an 
exceptional behaviour of the language, that is context dependent.

-manfred