add single-shot solving option

[rkaminsk]

See also potassco/clasp#64.

• add --single-shot option to enable some optimization that cannot be applied in the multi-shot case
• raise an error if more than one step is started in single-shot mode
• add unit tests

[ssardina]

@rkaminsk question on the --single-shot and the Python API: can the option be set via the configuration of the Control? I couldn't find it but maybe I am missing it?

(sorry I follow-up here just in case somebody else find it)

[rkaminsk]

The option has to be set upon creation of the control object. It cannot be set via the dynamic configuration.

[ssardina]

wow, thanks for the quick reply!

The option has to be set upon creation of the control object. It cannot be set via the dynamic configuration.

You mean via the arguments option of the Control class like this, right?

control = clingo.Control(arguments="--single-shot")

That is all good for my own application that creates a Control, but I couldn't see how to pass arguments if I use teh Application framework that comes with Clingo

Presumably the control object is created automatically, so is there any way of passing arguments like --single-shot?

[rkaminsk]

wow, thanks for the quick reply!

The option has to be set upon creation of the control object. It cannot be set via the dynamic configuration.

You mean via the arguments option of the Control class like this, right?

control = clingo.Control(arguments="--single-shot")

That is all good for my own application that creates a Control, but I couldn't see how to pass arguments if I use teh Application framework that comes with Clingo

Presumably the control object is created automatically, so is there any way of passing arguments like --single-shot?

For the application, it can be passed on the command line as with clingo.

In principle one can also inject it into the options befor calling clingo_main. It's a bit hacky, but might suite your purpose:

args = sys.argv[1:]
if not "--single-shot" in args:
    args.append("--single-shot")
clingo_main(App(), args)

[ssardina]

Ohh, I see... so is clingo_main() function the one that creates the Control object (and uses args as arguments) and passes it to main?