[Info-vax] Roadmap

[Arne Vajhøj]

On 1/6/2019 5:15 PM, gezelter at rlgsc.com wrote:
> On Sunday, January 6, 2019 at 12:16:48 PM UTC-5, Arne Vajhøj wrote:
>> On 1/6/2019 11:16 AM, gezelter at rlgsc.com wrote:
>>> In the case of floating point, perhaps all (repeat ALL) OpenVMS
>>> compilers should support a non-standard keyword "IEEE754" as an
>>> adjunct to REAL and DOUBLE. A "C"-ish example would be:
>>>
>>> IEEE754 float X; IEEE754 double Y;
>>>
>>> in FORTRAN:
>>>
>>> IEEE754 REAL*4 X; IEEE754 REAL*8 Y;
>>>
>>> This would allow the clarity in documenting mixed representation
>>> programs, e.g., programs which read/write one format while working
>>> internally in another. Often, such situations are, as I have noted
>>> elsewhere, not a voluntary choice. Historical data exists, libraries
>>> expect certain formats, etc.
>>>
>>> Doing this consistently across multiple compilers is, I admit, a
>>> chore. However, it is also a problem best addressed in a consistent
>>> manner, than ad hoc for each different compiler.
>>>
>>> My apologies to John for adding to his work queue.
>>
>> It would also make the code non-portable.
>>
>> Probably not a problem for Basic, Pascal etc..
>>
>> But for C, Fortran etc. then I see it as a problem.

> Having written a large amount of portable code over the years, I can
> assure you that portability (to different platforms) is not an issue
> in these cases.
Really?

John Reagan introduces IEEE754 keyword in VMS Fortran,
I write a program that use it, I move that program to Linux
and tries to compile it. What happens?

> However, the need that I noted is very common. Data compatibility is
> frequently needed, and data morphing is a common need.
The need to read and write foreign formats is common. VMS also
has some support for it.

The solution you provided is not common.

> In some languages (e.g., C/C++) the portability issue can be handled with lexical macros.

It is often possible to make C/C++ code "portable" by adding a number of
#ifdef/#define.

Quotation marks on "portable" on purpose.

Arne