AbstractConstraint

subclasses:

Constraint, SeenBefore,  IsIn, IsNotIn, Every,  Not, Any, Xor, CountLimit, IsEven, IsOdd, IsNil, NotNil

Constraints let you specify conditions in an OOP fashion.

You can perform logical operations on the constraint object itself to further 

filter or refine your query.

(

// Create a constraint.

c = 

Constraint({ arg obj; obj.even  })

and: Constraint({ arg obj; obj % 4 == 0 })

and: (Constraint({ arg obj; obj == 8 }).not);

)

c is now a constraint object that can be used to validate that an input

is even, divisible by 4 and is not the number 8.

c.value(3)

c.value(8)

c.value(4)

c.value(12)

This can be used any place a function that returns true/false is required.

eg. select, reject, every, any

(

// run numbers through it

50.do({

n = 40.rand;

[n,c.value(n)].postln

});

)

It can be used in place of a function for 

SequenceableCollections, Streams and Patterns

(

// filter a collection

Array.fill(100,{ 100.rand })

.select(c) // acts like a function

.do({ arg num; num.postln; });

)

(

// Use to filter a Pattern

p = Pseries(0,1,100)

.select(c);

)

// Unfiltered

Pseries(0,1,100).asStream.all.do({arg num; num.postln;})

// Filtered

p.asStream.all.do({ arg num; num.postln });

(

// and here is everybody that gets rejected by the constraint

p = Pseries(0,1,100)

.reject(c);

)

p.asStream.all.do({ arg num; num.postln });

The below example is expressed using only Constraint.

(

c = 

Constraint({ arg obj; obj.even  })

and: Constraint({ arg obj; obj % 4 == 0 })

and: (Constraint({ arg obj; obj == 8 }).not);

)

It could also be expressed this way

(

c = 

IsEven.new and:  Constraint({ arg obj; obj % 4 == 0 })

and: Constraint({ arg obj; obj != 8 });

)

Constraints respond to

.not

.or(aConstraint)

.and(aConstraint)

.xor(aConstraint)

.reject(aConstraint)

.select(aConstraint)

by returning a new compound constraint that expresses that logic.

(

c = IsEven.new;

d = Constraint({ arg num; num == 3 });

e = c or: d; // if its even or it is the number 3

)

(

c = IsEven.new;

d = Constraint({ arg num; num == 4 });

e = c.reject(d); // if its even and also reject it if it is the number 4

)