Originally posted by: HorstS

Hello!

I have a model in OPL using IBM ILOG CPLEX Optimization Studio 12.2.
Now I would like to add a new user-defined global constraint to my model.
Hence, I would like to write my own propagator (e.g., an 'alldifferent' that requires all variables to have a different value except if their value is 0).

From the documentation on 'writing complex custom constraints' I know
that this is feasible when using the C++/Java interface (e.g.,
by defining a new class of type 'IlcConstraint').

But is there a way to define a new propagtor directly within OPL?
And if not, is it possible to 'include' an externally defined propagtor in JAVA/C++ in an OPL model? Or is using the JAVA/C++ interface to OPL the only possibility to define a new propagator?

Cheers,
Horst
#CPOptimizer
#DecisionOptimization

Originally posted by: ArnaudS

Hi,

You should write the custom constraint in Java and add it to your model
in the main block (see flow control in the doc) using external java calls:

.mod file:

using CP; 

int n = 5; dvar 

int x[0..n] in 1..123465; dvar 

int y[0..n];   constraints 
{ allDifferent(x); 
}   main 
{ thisOplModel.generate();   IloOplImportJava(
"E:/workspace-OPL/CustomConstraint/bin");   
// add custom constraint to the model IloOplCallJava(
"mypackage.MyClass", 
// class name 
"addConstraint",            
// method name 
"",                  
// signature omitted, no ambiguity thisOplModel,
"x",
"y",thisOplModel.n+1);       
// parameters   

if ( cp.solve() ) 
{ thisOplModel.postProcess(); writeln(
"x: ", thisOplModel.x); writeln(
"y: ", thisOplModel.y); 
} 

else 
{ writeln(
"No solution!"); 
} 
}

Java class:

package mypackage;   

import ilog.concert.IloConstraint; 

import ilog.concert.IloException; 

import ilog.concert.IloIntVar; 

import ilog.concert.IloIntVarMap; 

import ilog.cp.IloCP; 

import ilog.cp.IloCustomConstraint; 

import ilog.opl.IloOplModel;   

public 

class MyClass 
{   

static 

public 

class MyCustomConstraint 

extends IloCustomConstraint 
{ 

private 

final IloIntVar _x; 

private 

final IloIntVar _y;   

public MyCustomConstraint(IloCP cp, IloIntVar x, IloIntVar y) 

throws IloException 
{ 

super(cp); _x = x; _y = y; this.addVar(x); this.addVar(y); 
}   

public 

void execute() 
{ setRange(_y, getMin(_x) * 2, getMax(_x) * 2); 
} 
}   

public 

static 

void addConstraint(IloOplModel model, String intMap1, String intMap2, 

int size) 

throws IloException 
{ IloIntVarMap xArr = model.getElement(intMap1).asIntVarMap(); IloIntVarMap yArr = model.getElement(intMap2).asIntVarMap();   IloCP cp = model.getCP();   

for (

int i = 0; i < size; i++) 
{ IloIntVar x = xArr.get(i); IloIntVar y = yArr.get(i); IloConstraint ct = 

new MyClass.MyCustomConstraint(cp, x, y); cp.add(ct); 
} 
} 
}

Hope this helps.

Bye,
Arnaud
#CPOptimizer
#DecisionOptimization