• Nick Sabalausky (Abscissa) (5/5) Mar 07 2018 I'm having trouble finding the documentation for what exactly the unary
• ketmar (3/8) Mar 07 2018 https://dlang.org/spec/operatoroverloading.html#boolean_operators
• Nick Sabalausky (Abscissa) (9/22) Mar 07 2018 Ah, thanks.
• ketmar (8/11) Mar 07 2018 exactly. if you want to convert object to a pointer safely, do this:
• Steven Schveighoffer (8/29) Mar 08 2018 One thing to keep in mind, assert(someObject) does more than just check
• Nick Sabalausky (Abscissa) (7/17) Mar 08 2018 Turns out it wasn't a class at all: As Jacob pointed out in my other

"Nick Sabalausky (Abscissa)" <SeeWebsiteToContactMe semitwist.com> writes:

I'm having trouble finding the documentation for what exactly the unary 
"not" operator does when applied to a class/interface object. Does this 
documentation exist somewhere?

I know at least part of it involves "is null", but I seem to remember 
hearing there was more to it than just that.

ketmar <ketmar ketmar.no-ip.org> writes:

Nick Sabalausky (Abscissa) wrote:

 I'm having trouble finding the documentation for what exactly the unary 
 "not" operator does when applied to a class/interface object. Does this 
 documentation exist somewhere?

 I know at least part of it involves "is null", but I seem to remember 
 hearing there was more to it than just that.

https://dlang.org/spec/operatoroverloading.html#boolean_operators

"Class references are converted to bool by checking to see if the class
reference is null or not."

"Nick Sabalausky (Abscissa)" <SeeWebsiteToContactMe semitwist.com> writes:

On 03/08/2018 12:05 AM, ketmar wrote:
 Nick Sabalausky (Abscissa) wrote:
 
 I'm having trouble finding the documentation for what exactly the 
 unary "not" operator does when applied to a class/interface object. 
 Does this documentation exist somewhere?

 I know at least part of it involves "is null", but I seem to remember 
 hearing there was more to it than just that.

 
 https://dlang.org/spec/operatoroverloading.html#boolean_operators
 
 "Class references are converted to bool by checking to see if the class 
 reference is null or not."

Ah, thanks.

But are we CERTAIN that's all there is to it? I have a non-reduced 
situation right now where outputting the address of a class reveals a 
non-null address, and yet assert(!!theObjectInQuestion) is failing. 
(this is occurring during stack unwinding, if that makes a difference)

(Or does &someObject return the address of the *reference* to the object 
rather than the address of the object?...You can see just how often I do 
OO in D ;) )

ketmar <ketmar ketmar.no-ip.org> writes:

Nick Sabalausky (Abscissa) wrote:

 (Or does &someObject return the address of the *reference* to the object 
 rather than the address of the object?...You can see just how often I do 
 OO in D ;) )

exactly. if you want to convert object to a pointer safely, do this:

	MyObject o;
	void* p = *cast(void**)&o;

this magic construct guarantees that you won't hit `opCast()` in 
`MyObject` (yes, somebody *can* write weird `opCast` for `void*`! ;-).

doing just `&o` gives you the address of a variable (on a stack, or in a 
tls), which is, obviously, never `null`. ;-)

Steven Schveighoffer <schveiguy yahoo.com> writes:

On 3/8/18 1:00 AM, Nick Sabalausky (Abscissa) wrote:
 On 03/08/2018 12:05 AM, ketmar wrote:
 Nick Sabalausky (Abscissa) wrote:

 I'm having trouble finding the documentation for what exactly the 
 unary "not" operator does when applied to a class/interface object. 
 Does this documentation exist somewhere?

 I know at least part of it involves "is null", but I seem to remember 
 hearing there was more to it than just that.

 https://dlang.org/spec/operatoroverloading.html#boolean_operators

 "Class references are converted to bool by checking to see if the 
 class reference is null or not."

 
 Ah, thanks.
 
 But are we CERTAIN that's all there is to it? I have a non-reduced 
 situation right now where outputting the address of a class reveals a 
 non-null address, and yet assert(!!theObjectInQuestion) is failing. 
 (this is occurring during stack unwinding, if that makes a difference)

One thing to keep in mind, assert(someObject) does more than just check 
if it's not null, it also runs the object's invariant to see if it's valid.

I'm not sure about assert(!!someObject), probably this is just checking 
for non-null, but I'm not sure if the compiler folds this into 
assert(someObject) (which would be a bug, but may explain things). To be 
more pedantic, I'd recommend assert(someObject !is null)

-Steve

"Nick Sabalausky (Abscissa)" <SeeWebsiteToContactMe semitwist.com> writes:

On 03/08/2018 05:31 AM, Steven Schveighoffer wrote:
 On 3/8/18 1:00 AM, Nick Sabalausky (Abscissa) wrote:
 But are we CERTAIN that's all there is to it? I have a non-reduced 
 situation right now where outputting the address of a class reveals a 
 non-null address, and yet assert(!!theObjectInQuestion) is failing. 
 (this is occurring during stack unwinding, if that makes a difference)


Turns out it wasn't a class at all: As Jacob pointed out in my other 
thread, it *used* to be a class/interface in a previous lib version 
(vibe's TCPConnection) but got changed to a struct without my noticing. 
Hence the seemingly weird behaviours.

 
 One thing to keep in mind, assert(someObject) does more than just check 
 if it's not null, it also runs the object's invariant to see if it's valid.
 

Ahh, right! *That's* the part I knew I'd heard about and was trying to 
remember.