On 07/08/2013, at 9:34 PM, Paul Gilmartin <[email protected]> wrote:

> On Tue, 6 Aug 2013 12:39:09 +0800, David Crayford wrote:
>> 
>> I've always liked the nice abstraction with the z/OS C/C++ FILE I/O
>> implementation. fopen() is a factory function which returns a
>> semi-opaque structure with two function pointers to read/write routines
>> (methods) which handle all
>> the different access methods (QSAM, BSAM, VSAM, UNIX, Hiperspaces etc).
>> It's a good design and an example of OO done well in C using pointers in
>> structs ;).
>> 
> In fact, in Assembler the DCB has much this character.  OPEN updates
> the DCB by adding pointers to the access method entry points.
> 

Shame it doesn't support VSAM. Or maybe ACB should support QSAM, BSAM etc. 

> Alas, IBM developers abandoned this paradigm.  One writes to the
> operator's console not using QSAM, but WTO;  one writes to the TSO
> terminal not using QSAM to SYSTSPRT, but TPUT.  And I believe I have
> evidence that FTP given the DD: construct does not Do the Right Thing
> of OPENing a DCB on that DDNAME, but chases control blocks to suss
> out the underlying object and performs its own allocation, probably
> thwarting any attempt of the caller to override attributes, etc.
> 

I prefer the UNIX philosophy where everything is a file. Programming is 
difficult enough without inconsistent interfaces. 


> 
> On Wed, 26 Jun 2013 07:33:40 -0400, Shmuel Metz (Seymour J.) wrote:
>> 
>>> What went wrong?
>> 
>> It started early: George Mealy is alleged to have called it "The rape
>> of the design integrity of OS/360" and blamed it on a lack of
>> standards enforcement.
> 
> -- gil
> 
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