[Info-vax] GKS : gopwk problem with VSI's version of GKS

[Joukj]

Stephen Hoffman wrote:
> On 2021-03-17 11:59:22 +0000, Paul Hardy said:
> 
>> Joukj <joukj at hrem.nano.tudelft.nl> wrote:
>>> Hi all,
>>>
>>> I try to call GKS from a Fortran program. All worked fine with de "HP 
>>> GKS". However when upgrading to "VSI GKS" I got problems 
>>> initializing  GKS. It looks like the call to GOPWK should be adapted:
>>>
>>> What always worked was:
>>> CALL GOPWK(1, 0 , GWSDEF )
>>> It looks like the second parameter is not integer anymore in VSI-GKS 
>>> but a character string (I get the error "Invalid representation of 
>>> integer in translated string")
>>>
>>> I have no idea what to fill  in for the second parameter to get the 
>>> default connection ID. The examples the installation stored on disk 
>>> only  show an integer parameter here.Who can get me a hint on how to 
>>> call GOPWK in a proper way.
>>>
>>> I tried this on OpenVMS8.4-2L1 with VSI-GKS 7.3 (and HP-GKS V7.2 for 
>>> reference) and VSI Fortran V8.3-104957-50Q83 running on IA64.
>>> regards Jouk
>>>
>>
>> In terms of the GKS standard, the second parameter must be an integer 
>> passed into GOPWK and is CONID the connection identifier - described 
>> as the channel that the operating system will use to communicate with 
>> the workstation - probably originally the Fortran unit number.
>>
>> If VSI is expecting a string, then it’s a bug/ violation of standard.
> 
> Well, no.
> 
> The argument in question here is of variable type, with that type 
> dependent on the values of another.
> 
> Related info:
> http://ngwww.ucar.edu/fund/chp6-10/workstations.html
> https://linux.die.net/man/3/ncl_gopwk
> http://vtda.org/docs/computing/DEC/VMS/AA-MJ29A-TE_DEC_GKS_FORTRAN_Binding_Reference_Manual_Apr1989.pdf 
> 
> http://vtda.org/docs/computing/DEC/VMS/AA-HW44C-TE_DEC_GKS_Reference_Manual_Volume_II_Apr1989.pdf 
> (appendix A; there's something to be said for a manual that's ~half 
> appendix, too. Also see that CONID_DEFAULT is also language-specific, on 
> page A-3)
> 
> I find vanishingly few references to GWSDEF, so I might wonder if that's 
> a now-archaic DEC extension.  And I'd wonder whether GWSDEF might 
> default differently in this GKS.
> 
> One of the few references to GWSDEF is on page 230 here: 
> http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.907.5093&rep=rep1&type=pdf 
> 

GWSDEF is defined in the gks.f files which comes with the installation 
and is also used in all the examples:

Directory SYS$COMMON:[SYSLIB]

GKS.F;1

Total of 1 file.
$) search gks.f GWSDEF
       INTEGER     GWSDEF,     GMOUTP,     GMINPT,     GWSWIS,
       PARAMETER(  GWSDEF=0,   GMOUTP=2,   GMINPT=3 ,  GWSWIS=5,


> 
> The need for some Fortran code changes here would not be surprising.
> 
> DECwindows has one or two of these cases, too; where a locally-defined X 
> argument is different from what's locally-defined on most other 
> platforms. q.v. XtAppAddInput
> 
> Cue discussions of the complexity of compiler-time type checking with 
> some APIs, too.
> 
> And then there are the discussions of OpenGL and Vulkan, but those 
> discussions can sometimes get too Metal.
> 
> 
>