The RemovePermanent command removes the permanent entry for which key is the key.  The cache table can be given directly as cache, or cache can refer to a procedure that has, or can have, a cache remember table.  If such a procedure is given and it has a cache remember table, the permanent entry is removed from that table.  If the procedure does not have a table, no action is taken.

To handle an expression sequence as a key, key must be given in a list.  The actual key used for the entry is op(key).

Calling RemovePermanent is the only way to remove a permanent entry from a cache table.

To add a permanent entry to a cache table, use AddPermanent.

For more information on cache tables, see Cache Package.

$\mathrm{c1}≔\mathrm{Cache}\left(\right)$

$\mathrm{c1}≔\mathrm{Cache}\left(512\right)$

$\mathrm{Cache}:-\mathrm{AddPermanent}\left(\mathrm{c1}\,\left[x\right]\,y\right)$

$\mathrm{Cache}:-\mathrm{AddPermanent}\left(\mathrm{c1}\,\left[y\right]\,z\right)$

$\mathrm{eval}\left(\mathrm{c1}\right)$

$\mathrm{Cache}\left(512\,'\mathrm{permanent}'=\left[y=z\,x=y\right]\right)$

$\mathrm{Cache}:-\mathrm{RemovePermanent}\left(\mathrm{c1}\,\left[x\right]\right)$

$\mathrm{eval}\left(\mathrm{c1}\right)$

$\mathrm{Cache}\left(512\,'\mathrm{permanent}'=\left[y=z\right]\right)$

$\mathrm{Cache}:-\mathrm{RemovePermanent}\left(\mathrm{c1}\,\left[y\right]\right)$

$\mathrm{eval}\left(\mathrm{c1}\right)$

$\mathrm{Cache}\left(512\right)$

p := proc(x,y) option cache; x+y; end proc;

$p≔\mathbf{proc}\left(x\,y\right)\mathbf{option}\mathrm{cache}\;x\+y\mathbf{end\; proc}$

$p\left(1\,1\right)$

$2$

$\mathrm{Cache}:-\mathrm{AddPermanent}\left(p\,\left[2\,2\right]\,8\right)$

$\mathrm{Cache}:-\mathrm{AddPermanent}\left(p\,\left[1\,2\right]\,5\right)$

$p\left(2\,2\right)$

$8$

$p\left(1\,2\right)$

$5$

$\mathrm{Cache}:-\mathrm{RemovePermanent}\left(p\,\left[2\,2\right]\right)$

$p\left(2\,2\right)$

$4$

$\mathrm{op}\left(4\,\mathrm{eval}\left(p\right)\right)$

$\mathrm{Cache}\left(512\,'\mathrm{temporary}'=\left[\left(1\,1\right)=2\,\left(2\,2\right)=4\right]\,'\mathrm{permanent}'=\left[\left(1\,2\right)=5\right]\right)$

$\mathrm{Cache}:-\mathrm{RemovePermanent}\left(p\,\left[1\,2\right]\right)$

$p\left(1\,2\right)$

$3$

$\mathrm{op}\left(4\,\mathrm{eval}\left(p\right)\right)$

$\mathrm{Cache}\left(512\,'\mathrm{temporary}'=\left[\left(1\,2\right)=3\,\left(1\,1\right)=2\,\left(2\,2\right)=4\right]\right)$