On 3/10/22 07:18, Farley, Peter x23353 wrote:
Where, for instance, in the documentation that you linked to is there information on whether the python "open()" function for files will or will not support direct access to MVS datasets without transferring them down to the Unix file system? I.E., are either of these calls to the open() function valid or not:Myfile = open("//'MVS.DATA.SET.NAME", "rt", ccsid="1047") Myfile = open("//:DDNAME", "rt", ccsid="1047") # This of course assumes that a call to "bpxunix" (or by other means) has been used to establish a DD allocation in the AS where the python program is executing
This will *never* happen. If you read the doc WRT tagging behaviors you will understand why https://www.ibm.com/docs/en/python-zos/3.9?topic=translation-tagging-behaviors. Rocket's Python port supported reading MVS data sets but it was not a documented feature and was used with great care. Patching the Python core I/O libraries to support MVS data sets is not a great idea. It's much better to write a specific library that *only* support MVS data sets and not z/OS UNIX files. A good reference implementation is the JZOS ZFile class. If you open an RFE IBM may do this. Or maybe the community can contribute? Either way it's going to be implemented as a specific package.
Porting tools to support MVS data sets in trivial. They use open() because it's a low-level API and read/write support sockets, FIFO's, pipes etc. It's not just a case of replacing open with fopen(). Python implements a fdopen() https://docs.python.org/3/library/os.html#os.fdopen method for wrapping file descriptors.
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