[Cgl] Re: [Coin-discuss] generateCpp()

[John J Forrest]

fmargot at andrew.cmu.edu wrote on 10/03/2006 03:32:57 PM:

> 
> 
> On Mon, 2 Oct 2006, John J Forrest wrote:
> 
> > Whom else!
> >
> > If a cut generator (or heuristic etc) is modified from its default
> > constructor and then this is called  a series of lines of code is 
output
> > which changes the default generator to the current state.
> >
> 
> Except that there is some kind of key associated with the lines of code:
> I see lines starting with
> 
> 0
> 3
> 4

The way it works is that just before going into CbcModel branch and cut 
the stand-alone solver sees that -cpp was set (or cpp if interactive).  It 
goes through all generators, heuristics CbcModel and associated solver 
asking them to write lines to file.  Then it calls a bit of code called 
generateCode (in CoinSolve.cpp).  This goes through file several times - 
first doing ones with 0, then 1 etc.  Some levels may be skipped so if cpp 
was just 1 then it does not put out commands where the generator has a 
default value (i.e. it only puts out level 3 and not level 4).  If you 
want the default changes (so you can modify them ) then you up the cpp 
value.
> 
> What is the meaning of these keys? Is it possible to have a line
> starting with other numbers? What about 1 and 2?

0,3,5 and 8 always go out (cpp==0)
1 and 6 go out if cpp==1
2 4 and 7 go out if cpp>1

You can see what they were meant to be if you search for std::string 
header in CoinSolve.cpp as those are the comments which go out in created 
code.


> 
> > I wrote it when feeling in need of light entertainment, however it has 
a
> > serious purpose.  If you use the stand-alone cbc (or any other solver)
> > then your commands may change the behavior of the cut generators. When
> > you like the result you add -cpp 1 (other numbers create more output) 
and
> > lo and behold  a driver is created which mimics those actions.
> >
> 
> I add "-cpp 1" to what? Command line of cbc?
> 
> Francois
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