The MASM Forum

Hi Guys,

I am trying to make a simple STRUCT and I am finding that if I have a member 'Width' I get compilation errors.

Is 'Width' a reserved thing?

This wont compile


LLDXGI_MODE_DESC STRUCT
Width DWORD 0
Height DWORD 0
LLDXGI_MODE_DESC ENDS


But this will


LLDXGI_MODE_DESC STRUCT
someOtherWidth DWORD 0
Height DWORD 0
LLDXGI_MODE_DESC ENDS

Thanks :)

Quote from: Lonewolff on March 16, 2016, 05:02:27 PMIs 'Width' a reserved thing?

Yes, it's used with records. Use _Width instead - see Windows.inc for some examples.

Here is a keyword list, if you don't find it.

Cool. Thanks for the heads up :)

Having said that. If there is an item in the SDK that has a member 'width' and you prefix it as '_width', won't that break SDK compatibility and lead to further confusion?

Quote from: Lonewolff on March 17, 2016, 10:26:47 AM
Having said that. If there is an item in the SDK that has a member 'width' and you prefix it as '_width', won't that break SDK compatibility and lead to further confusion?

Inevitably! There are several examples in Windows.inc and elsewhere that use the "_" to overcome this problem:

SDK:
typedef struct NMLVSCROLL {
  NMHDR hdr;
  int   dx;
  int   dy;
} NMLVSCROLL, *LPNMLVSCROLL;

Windows.inc:
NMLVSCROLL STRUCT
   hdr                    NMHDR <>
   _dx                    DWORD ?
   dy                     DWORD ?
NMLVSCROLL ENDS

There is no other option: dx is a register, the lower half of edx :(

Effectively, the Microsoft Windows API is not compatible with the Microsoft Macro Assembler 8)

Fortunately, we simply got used to it :icon_mrgreen:

Hehe, fair enough.

It's probably too late now, but wouldn't it have been logical to prefix all members with _ and keep a standard across the whole library?

Quote from: Lonewolff on March 17, 2016, 10:58:53 AMwouldn't it have been logical to prefix all members with _ and keep a standard across the whole library?

It's really only a handful of cases. Having underscores all over the place would be very confusing.

Wouldn't uniform _'s across the whole API be less confusing than random occurances?

Things like 'width' are pretty common in structures.

To avoid those things i usually use a prefix for the struct mostly 1 character long.

for your Structure

LLDXGI_MODE_DESC STRUCT
Width DWORD 0
Height DWORD 0
LLDXGI_MODE_DESC ENDS

i would have used something like

LLDXGI_MODE_DESC STRUCT
mWidth DWORD 0
mHeight DWORD 0
LLDXGI_MODE_DESC ENDS[b]

(if there are other modes you could use an 'd' instead)
imo it also looks better.
But I've got a small question:
Why Init the Elements with 0? I thought it's more useful to create structs with unknown values ('?').
Or can i use the 0 (or any other value)as pre initialization?

Regards

Quote from: BolterVi on March 17, 2016, 10:38:53 PM
To avoid those things i usually use a prefix for the struct mostly 1 character long.
...
I thought it's more useful to create structs with unknown values ('?')

You can use whatever prefix you want for your own structures, but for documented Windows API structures it is a really bad idea to modify them. Unless you are forced to because in the language of your choice dx or Width are reserved words.

Re unknown values: dd ? is OK for most uses. Remember you do not allocate anything when you formulate a STRUCT. It is only when you write
myRc RECT <1, 2, 3, 4>
when memory gets reserved.