Re: Predicate ordering when using current_predicate/1

[Sean Charles]

On 23 Nov 2013, at 11:28, Daniel Diaz <address@hidden> wrote:

Hi Sean

Well done !

Thanks. Praise indeed. Sadly lacking in the day job lately!

However, I don’t understand why you added the call to keysort/2 since setof/3 already sorts the list (this is the only difference between setof/ and bagof/3). You can remove it.

I wasn’t sure about that either because I am returning a pair with Line-Name i.e. line-number and test function and I wasn’t sure *how* the default sort would handle that so I rolled my own. Basically I was not sure what the collation order would be for my list. I don’t think the documentation says what it does to determine the ordering so I took no chances!

 I *will* take it out and see what happens though. In the documentation it says that it uses "sort(I,Instances)” but I couldn’t seem to relate that to my code. I will re-visit and try to understand again. One thing I know, it is worth getting good with the debugger which I am quite familiar with now.

PS: about sockets: I have put a version in the git which adds the SO_REUSEADDR option at socket creation. To get it:

git clone git://git.code.sf.net/p/gprolog/code gprolog-code

That’s nice to know… I will do a build today to get the “~” fix you did too. Getting the dreaded “address already in use” can be really irritating when you are rapid fire developing some server or client stuff.

BTW: if you write on the socket, you may to call flush_output(SO) to be sure the data is sent (and thus accessible on the other side).

I have done enough with sockets over the years to know flush() is your friend! I will add a flush to be safe.

Lunch beckons, that some basketball with my son but tonight I hack for England. Having learned Lisp, Erlang, Haskell I am starting to think that Prolog is what I have been “yearning for” all my life! Oh my god, did I just say that! Yes, you did, no go out and get a life 

:)

All the best,

Sean.

Le 22 nov. 2013 à 23:43, Sean Charles <address@hidden> a écrit :

Danieal,

Mission accomplished!

I ran with what you gave me and I now have a process that executes tests in the same order as they are declared in the source text. I had to learn (very quickly) about the A-B pair notation, something I had not seen before but as with the predicate indicator thing, once you know how it works the rest is easy…easier.

Here’s what I ended up with:

run_tests :-

        get_all_tests(AllTests),

        keysort(AllTests, SortedTests),

        maplist(exec_test, SortedTests),

The get_all_tests/1 predicate and the supporting acts look like this:

get_all_tests(Tests) :-

setof(Line-Name, get_one_test(Name, Line), Tests).

get_one_test(Name, Line) :-

current_predicate(Name/0),

atom_concat('test_', _, Name),

predicate_property(Name, prolog_line(Line)).

exec_test(_-TestFunction) :- /* omitted for brevity! */

Essentially I get all the test_ predicates then keysort/2 them into line number order and then maplist/2 over the exec_test/1 function which is now modified to accept a pair. Damn that’s useful to know!

So, once again, thank you very mud for your support in helping me out.

I am going to try to finish my Redis tests over the weekend and then I am going to update my “main” project with this improved code. in fact, I might even create a little github project and then include it as a dependency or something like that later on.

Have a great weekend!

:)

Sean.

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