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

[Stephen Hoffman]

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 


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.



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