[Swift-devel] Multiple output files

[Michael Wilde]

Mihael, All,

I'd like to propose a Swift/K feature to provide a reasonable solution 
to this very common need for an app to return a dynamically determined 
set of files.

file dynarry[ ] <runtime; prefix="myoutput.", suffix=".out", indexes="int">;

dynarry = myApp(myArgs);

The "runtime" mapper should initially have the same arguments and 
semantics (roughly) as simple_mapper, except for two new arguments:

  "indexes" which determines how the matched file names will be indexed 
in the returned array
"int" | "string" | "sequential"
sequential: return the matched files as consecutive integer indices 
starting with 0
int: expect the filename component between prefix and suffix to be 
convertible to an integer, and use that as the index
eg myfile.012.out and myfile.204.out will return an array with the 
mapped files at indices 12 and 204.
string: similar to int but return a string-indexed associative array.
"sequential" is simplest and should be the default.

"paths" which determines if the match names will be absolute or relative 
to the job dir
paths="relative" | "absolute"
(may not be needed if this can be determined uniquely based on the 
location argument.

swiftwrap will allow array variables mapped in this manner to have any 
number of files, including zero. I.e. "runtime-mapped" files should not 
be listed in the expected output list for an app invocation. Its up to 
the users app to ensure that some files match the pattern. An additional 
arg could set e.g. minfiles and/or maxfiles, in which case the wrapper 
code needs to validate the count of files matched and returned, but not 
their exact names.

We can call this mapper "experimental" until we validate its usability 
and suitability as a permanent feature. But as we hope to revise the 
entire mapper family and semantics, in a sense all mappers are subject 
to change.

Mihael, is the definition sound, and how long would it take you to 
develop it?

Thanks,

- Mike