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manual:chapter6:stack:cmd_stkdrop [2019/10/09 09:43]
claudio |
manual:chapter6:stack:cmd_stkdrop [2019/11/03 15:17] (current)
jojo1973 |
| ==== STKDROP ==== | ==== STKDROP ==== |
| ---- | ---- |
| <callout type="primary" color="" icon="fa fa-comment" title="Description"> | <callout type="primary" color="" icon="fa fa-book" title="Synopsis"> |
| ---- | ---- |
| Drop a stack snapshot from the top of the "stack of stacks". The snapshot contents will be lost. | Drop a snapshot from the top of the Undo stack |
| </callout> | </callout> |
| |
| <callout color="crimson" icon="fa fa-indent" title="Stack Diagram"> | <callout color="green" icon="fa fa-indent" title="Stack Diagram"> |
| ---- | ---- |
| ^ __Input Stack__ ^ ^ __Output Stack__ ^ | ^ __Input Stack__ ^ ^ __Output Stack__ ^ |
| | | **→** | | | | | **→** | | |
| | //Level 1// | **→** | //Level 1// | | | //Level 1// | //→// | //Level 1// | |
| |
| {{page>manual:chapter6:aux:legend&nofooter&noeditbtn&inline}} | {{page>manual:chapter6:aux:legend&nofooter&noeditbtn&inline}} |
| |
| | {{fa>times?lg&color=red}} **Support for inclusion in symbolic expressions** | | |**Type**| [[manual:chapter5:basics#commands|Command]] || |
| | {{fa>times?lg&color=red}} **Support for parallel list processing** | | |**Parallel list processing**| [[manual:chapter5:listproc#group-1commands-that-cannot-parallel-process|Group 1]] || |
| | {{fa>times?lg&color=red}} **Affected by flags** | | |**Affected by flags**| None || |
| </callout> | </callout> |
| |
| <callout type="warning" icon="fa fa-thumbs-down" title="Compatibility"> | <callout color="orangered" icon="fa fa-comment" title="Description"> |
| ---- | ---- |
| This command is new in newRPL, does not exist in userRPL. | The ''STKDROP'' command deletes the snapshot on the top of the Undo stack and subsequently all remaining snapshots drop one place. |
| | |
| | The command has little utility in interactive mode, because before ''STKDROP'' is executed a snapshot of the stack is pushed on the Undo stack: the only effect of ''STKDROP'' would be to delete the copy that was just made, leaving the Undo stack unchanged (except for the fact that its level 8 would have been lost in the process). |
| | </callout> |
| | |
| | <callout type="danger" icon="true" title="Compatibility"> |
| | ---- |
| | This command is new in newRPL and does not exist in userRPL. |
| </callout> | </callout> |
| |
| <callout type="info" icon="true" title="Usage"> | <callout type="info" icon="true" title="Usage"> |
| ---- | ---- |
| The following program: | The following program |
| <code> | <code> |
| « 123 | « "ABC" |
| | STKPUSH |
| | CLEAR |
| | 123 |
| 456 | 456 |
| 789 | 789 |
| 999 | 999 |
| STKDROP | STKDROP |
| | STKPOP |
| » | » |
| </code> | </code> |
| A snapshot containing numbers 123, 456, 789 will be pushed onto the "stack of stacks", then removed from the stack with ''CLEAR''. Finally, the snapshot will be removed from the "stack of stacks". | creates the following stack (before ''STKDROP'' is executed) |
| | <code> |
| | 1: 999 |
| | …………………………………………………………………………………… |
| | </code> |
| | The effect of ''STKPOP'' is to replace it with |
| | <code> |
| | 1: "ABC" |
| | …………………………………………………………………………………… |
| | </code> |
| </callout> | </callout> |
| |
| <callout color="darkslategray" icon="fa fa-hand-o-right" title="Related Commands"> | <callout color="darkgray" icon="fa fa-hand-o-right" title="Related Commands"> |
| | ---- |
| {{page>manual:chapter6:stack&nofooter&noeditbtn&inline}} | {{page>manual:chapter6:stack&nofooter&noeditbtn&inline}} |
| </callout> | </callout> |