Returns the first object in a mailbox.
mp
mailbox-peek mailbox => result, value-p
mailbox⇩ |
A mailbox. |
result⇩ |
Any object or nil . |
value-p⇩ | t or nil . |
The function mailbox-peek
returns the first object in the mailbox without removing it. If the mailbox is empty, nil
is returned.
If the mailbox mailbox is not empty, the function mailbox-peek
returns the first object in the mailbox without removing it. The second returned value value-p is t
.
If mailbox is empty, both return values result and value-p are nil
.
mailbox-peek
needs to lock the mailbox, which means it is significantly slower than mailbox-not-empty-p, and also may affect other processes. In most cases, mailbox-not-empty-p is sufficient and hence is preferable.
mailbox-empty-p
mailbox-not-empty-p
mailbox-send
mailbox-read
make-mailbox
19.6.3 Communication between processes and synchronization
LispWorks® User Guide and Reference Manual - 01 Dec 2021 19:30:51