Polymorphism: Difference between revisions

Line 3,239:

You could embed routine_ids in the structures to emulate virtual functions.

There are no private members here; for that I would write something that returns integer ids to the outside world.

<lang Phix>type point(object o)

return sequence(o) and length(o)=2 and atom(o[1]) and atom(o[2])

end type

function new_point(atom x=0, atom y=0)

type point(object o)

return {x,y}

return sequence(o) and length(o)=2 and atom(o[1]) and atom(o[2])

end function

end type

function new_point(atom x=0, atom y=0)

return {x,y}

end function

type circle(object o)

return sequence(o) and length(o)=2 and point(o[1]) and atom(o[2])

end type

function new_circle(object x=0, atom y=0, atom r=0)

if point(x) then

r = y -- assume r got passed in y

return {x,r} -- {point,r}

end if

return {{x,y},r} -- {point,r}

-- (or {new_point(x,y),r} if you prefer)

end function

point p = new_point(4,5)

circle c1 = new_circle(p,6),

c2 = new_circle(4,5,6}

?c1

?c2

type circle(object o)

return sequence(o) and length(o)=2 and point(o[1]) and atom(o[2])

end type

function new_circle(object x=0, atom y=0, atom r=0)

if point(x) then

r = y -- assume r got passed in y

return {x,r} -- {point,r}

end if

return {{x,y},r} -- {point,r}

-- (or {new_point(x,y),r} if you prefer)

end function

point p = new_point(4,5)

circle c1 = new_circle(p,6),

c2 = new_circle(4,5,6}

?c1

?c2</lang>

<pre>

Line 3,276:

Line 3,280:

Destructors are not shown, a procedure ~Point() would work but is not formally documented or guaranteed to be called in a timely fashion, should (eg) print() happen to be hanging on to a reference to it, until you print something else or unless you invoke an explicit delete(''instance'').

<lang Phix>class Point

atom x, y

function Point(object x, atom y=0)

if Point(x) then

this.x = x.x

this.y = x.y

else

this.x = x

this.y = y

end if

return this

end function

function get_x() return x end function

function get_y() return y end function

procedure set_x(atom x) this.x = x end procedure

procedure set_y(atom y) this.y = y end procedure

procedure show()

printf(1,"point (%g,%g)\n",{x,y})

end procedure

end class

class Circle extends Point

class Point

atom r

atom x, y

function Circle(object x, atom y=0, r=0)

function Point(object x, atom y=0)

if Circle(x) then

if Point(x) then

this.x = x.x

this.x = x.x

this.y = x.y

this.y = x.y

this.r = x.r

else

elsif Point(x) then

this.x = x

r = y -- assume r got passed in y

this.y = y

this.x = x.x

end if

this.y = x.y

return this

this.r = r

end function

else

function get_x() return x end function

this.x = x

function get_y() return y end function

this.y = y

procedure set_x(atom x) this.x = x end procedure

this.r = r

procedure set_y(atom y) this.y = y end procedure

end if

procedure show()

return this

printf(1,"point (%g,%g)\n",{x,y})

end function

end procedure

function get_r() return r end function

end class

procedure set_r(atom r) this.r = r end procedure

procedure show()

printf(1,"circle (%g,%g,%g)\n",{x,y,r})

end procedure

end class

class Circle extends Point

Point p1 = new({4,5}),

atom r

p2 = new({p1})

function Circle(object x, atom y=0, r=0)

p1.y = 7

if Circle(x) then

Circle c1 = new({p1,9}),

this.x = x.x

c2 = new({c1}),

this.y = x.y

c3 = new({10,11,12})

this.r = x.r

c1.r = 8

elsif Point(x) then

p1.show()

r = y -- assume r got passed in y

p2.show()

this.x = x.x

c1.show()

this.y = x.y

c2.show()

this.r = r

c3.show()</lang>

else

this.x = x

this.y = y

this.r = r

end if

return this

end function

function get_r() return r end function

procedure set_r(atom r) this.r = r end procedure

procedure show()

printf(1,"circle (%g,%g,%g)\n",{x,y,r})

end procedure

end class

Point p1 = new({4,5}),

p2 = new({p1})

p1.y = 7

Circle c1 = new({p1,9}),

c2 = new({c1}),

c3 = new({10,11,12})

c1.r = 8

p1.show()

p2.show()

c1.show()

c2.show()

c3.show()

<pre>