Hi,

I'm using boxes with relative ease and everything seems to be working properly. I have a problem with the Box.toString() method, though. Is there a way to make it work with objects or structs?

Thanks,
--AJG.

"AJG" <AJG_member@pathlink.com> wrote in message news:ddubsm$1llp$1@digitaldaemon.com...
> Hi,
>
> I'm using boxes with relative ease and everything seems to be working
> properly.
> I have a problem with the Box.toString() method, though. Is there a way to
> make
> it work with objects or structs?
>
> Thanks,
> --AJG.
>
>

I can't reproduce any problem with objects - perhaps you mean interfaces? With structs there's no default toString. Note when boxing an interface I think you need to explicitly cast it to Object before boxing but I'm not sure.

Hi,

So for example, what do you get here:

# class Test {
#     real m_Real;
#     this(real r) { m_Real = r; }
#     char[] toString() {
#          return (std.string.toString(m_Real));
#     }
# }

# import std.boxer;
#
# void main() {
#     Box b = box(new Test(4.2));
#     std.stdio.writefln("Test=" ~ b.toString());
# }

I get:
Test=nan

Or something like that. (Don't have a compiler available; please excuse any
typos in there).

I would like to get:
Test=4.2

------

Also, what does casting a struct to an Object do? Seems kinda weird, going from value to reference?

Thanks,
--AJG.


In article <ddviv4$2u8f$1@digitaldaemon.com>, Ben Hinkle says...
>"AJG" <AJG_member@pathlink.com> wrote in message news:ddubsm$1llp$1@digitaldaemon.com...
>> Hi,
>>
>> I'm using boxes with relative ease and everything seems to be working
>> properly.
>> I have a problem with the Box.toString() method, though. Is there a way to
>> make
>> it work with objects or structs?
>>
>> Thanks,
>> --AJG.
>>
>>
>
>I can't reproduce any problem with objects - perhaps you mean interfaces? With structs there's no default toString. Note when boxing an interface I think you need to explicitly cast it to Object before boxing but I'm not sure.
>
>

> Or something like that. (Don't have a compiler available; please excuse
> any
> typos in there).
>
> I would like to get:
> Test=4.2

I get Test=4.2 on Windows using dmd.129

> ------
>
> Also, what does casting a struct to an Object do? Seems kinda weird, going
> from
> value to reference?

If you are referring to my reply I said cast an interface to Object - not struct to Object. You can't cast a struct to Object as you probably guessed.

Hi,

>> Or something like that. (Don't have a compiler available; please excuse
>> any typos in there).
>> I would like to get:
>> Test=4.2
>I get Test=4.2 on Windows using dmd.129

Will have to try that again soon. Thanks.

>> Also, what does casting a struct to an Object do? Seems kinda weird, going
>> from
>> value to reference?
>
>If you are referring to my reply I said cast an interface to Object - not struct to Object. You can't cast a struct to Object as you probably guessed.

Whoops. Misread that sentence a little bit ;)

Though I was kind of interested in the struct to object casting, hypothetically. Could be a way to automagically pass from the stack to the GC heap.

Ok, anyway, then what is the expected result when you toString() a box with a struct? Is there a defined behaviour?

Thanks again,
--AJG.

> Though I was kind of interested in the struct to object casting,
> hypothetically.
> Could be a way to automagically pass from the stack to the GC heap.
>
> Ok, anyway, then what is the expected result when you toString() a box
> with a
> struct? Is there a defined behaviour?

I think it does whatever std.format.doFormat does with a struct - probably throw a FormatError exception.

ps - I wish Walter would do something about the Error vs Exception naming "convention"...

Hi,

First- you were right about Objects. There was a ridiculously diabolical bug in my code.

>> Ok, anyway, then what is the expected result when you toString() a box
>> with a
>> struct? Is there a defined behaviour?
>
>I think it does whatever std.format.doFormat does with a struct - probably throw a FormatError exception.

Hm... I even tried a toString() method in my struct and it still crashed and burnt. It would seem logical to me to call this method for a struct too.

>ps - I wish Walter would do something about the Error vs Exception naming "convention"...

Yes. This is entirely misleading.

Thanks,
--AJG.