Cleanup Issue DEFSTRUCT-SLOTS-CONSTRAINTS-NUMBER
- Status
- Passed, 1988 (not sure which meeting)
- Category
- CHANGE
- References
- CLtL p.307 & 86-003 p.4
Problem Description
Structures defined by defstruct currently are required to have at least one slot. This seems to have been a mistake in the design of the language.Proposal (ALLOW-ZERO)
Allow a call to defstruct to have zero slot-descriptions. i.e. change the + to a * in the syntax of calls to defstruct given at the bottom of page 307 of CLtL.Test Cases
(defstruct s), which is not allowed according to CLtL, would be allowed.Rationale
The current restriction is in marked contrast to the generality allowed elsewhere in the language. And removing it slightly increases the usefulness of defstruct - by allowing the zero slot case when it may be deemed useful and by not requiring a check for it when it doesn't matter.Current Practice
KCL allows zero slots.Cost to Implementors
None for implementations that currently allow zero slots. Very slight for others.Cost to Users
None.Benefits
Slightly increases the usefulness of defstruct and is aesthetic.Aesthetics
In general, it is more aesthetic to allow for generality rather than to specifically prohibit a particular case. And the generality in this case is consistent with that of many other features of the language, such as that arrays can be empty, functions like + and list can take zero arguments, etc.Discussion
Although this issue was mentioned in Guy's original issues file, it has not been officially discussed since.Edit History
- Revision 1 by Skona Brittain 05/13/88