Parametric polymorphism: Difference between revisions

=={{header|REXX}}==

This REXX programming example is modeled after the   '''D'''   example.

<lang rexx>/*REXX program demonstrates a method of parametric polymorphism in REXX.*/

call newRoot 1.00, 3 /*new root and indicate 3 stems. */

/* [↓] no need to label the stems*/

call addStem 1.10 /*new stem and its initial value.*/

call addStem 1.11 /* " " " " " " */

call addStem 1.12 /* " " " " " " */

call addStem 1.20 /* " " " " " " */

call addStem 1.21 /* " " " " " " */

call addStem 1.22 /* " " " " " " */

call sayNodes /*display nicely formatted values*/

call modRoot 50 /*MOD will added 50 to all stems.*/

call sayNodes /*display nicely formatted values*/

exit /*stick a fork in it, we're done.*/

/*──────────────────────────────────MODROOT─────────────────────────────*/

modRoot: do j=1 for nodes /*traipse through all the nodes. */

do k=1 for stems; _=root.j.k; ?=datatype(_,'N')

if ? then root.j.k=_+arg(1) /*can stem be added to?*/

end /*k*/ /* [↑] only add if it's numeric.*/

end /*j*/

return

/*──────────────────────────────────NEWROOT─────────────────────────────*/

newRoot: stems=arg(2); nodes=-1; /*set NODES to a kind of "null". */

call addStem copies('─',9); call addStem arg(1)

return

/*──────────────────────────────────SAYNODES────────────────────────────*/

sayNodes: say; do j=0 to nodes; _= /*each node gets shown*/

do k=1 for stems; _=_ right(root.j.k,9); end /*k*/

say substr(_,2) /*ignore the 1st blank*/

end /*j*/

say left('', stems*9+stems) || '('nodes" nodes)" /*also show # of nodes*/

return

/*──────────────────────────────────ADDSTEM─────────────────────────────*/

addStem: nodes=nodes+1; do j=1 for stems; root.nodes.j=arg(1); end /*j*/

return</lang>

'''output'''

<pre>

───────── ───────── ─────────

1.00 1.00 1.00

1.10 1.10 1.10

1.11 1.11 1.11

1.12 1.12 1.12

1.20 1.20 1.20

1.21 1.21 1.21

1.22 1.22 1.22

(7 nodes)

───────── ───────── ─────────

51.00 51.00 51.00

51.10 51.10 51.10

51.11 51.11 51.11

51.12 51.12 51.12

51.20 51.20 51.20

51.21 51.21 51.21

51.22 51.22 51.22

(7 nodes)

</pre>