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Clarify that #s(hash-table ...) doesn't always create a new hash table

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* doc/lispref/hash.texi (Creating Hash): Note that the printed
representation doesn't necessarily create a new table (bug#23417).

* doc/lispref/lists.texi (Rearrangement): Link to Self-Evaluating
Forms to further expand upon immutability.
This commit is contained in:
Lars Ingebrigtsen 2021-02-07 14:47:09 +01:00
parent e0c9399454
commit a1a31ecb40
2 changed files with 14 additions and 8 deletions
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9
doc/lispref/hash.texi
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@ -150,11 +150,11 @@ multiplied by an approximation to this value. The default for
@end table
@end defun
You can also create a new hash table using the printed representation
You can also create a hash table using the printed representation
for hash tables. The Lisp reader can read this printed
representation, provided each element in the specified hash table has
a valid read syntax (@pxref{Printed Representation}). For instance,
the following specifies a new hash table containing the keys
the following specifies a hash table containing the keys
@code{key1} and @code{key2} (both symbols) associated with @code{val1}
(a symbol) and @code{300} (a number) respectively.
@ -162,6 +162,11 @@ the following specifies a new hash table containing the keys
#s(hash-table size 30 data (key1 val1 key2 300))
@end example
Note, however, that when using this in Emacs Lisp code, it's
undefined whether this creates a new hash table or not. If you want
to create a new hash table, you should always use
@code{make-hash-table} (@pxref{Self-Evaluating Forms}).
@noindent
The printed representation for a hash table consists of @samp{#s}
followed by a list beginning with @samp{hash-table}. The rest of the

13
doc/lispref/lists.texi
View file

@ -1168,13 +1168,14 @@ x
@end group
@end example
However, the other arguments (all but the last) should be mutable lists.
However, the other arguments (all but the last) should be mutable
lists.
A common pitfall is to use a constant list as a non-last
argument to @code{nconc}. If you do this, the resulting behavior
is undefined. It is possible that your program will change
each time you run it! Here is what might happen (though this
is not guaranteed to happen):
A common pitfall is to use a constant list as a non-last argument to
@code{nconc}. If you do this, the resulting behavior is undefined
(@pxref{Self-Evaluating Forms}). It is possible that your program
will change each time you run it! Here is what might happen (though
this is not guaranteed to happen):
@smallexample
@group