1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
|
<html><head><title>XLISP rplaca</title>
<link rel="stylesheet" type="text/css" href="reference.css">
</head>
<body>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
<a href="../manual/contents.htm">Contents</a> |
<a href="../tutorials/tutorials.htm">Tutorials</a> |
<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>
<hr>
<h1>rplaca</h1>
<hr>
<p><table cellpadding="0" cellspacing="0" style="margin-left:10px"><tbody>
<tr valign="top">
<td><nobr>Type:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>function (subr)</nobr></td>
</tr>
<tr valign="top">
<td><nobr>Source:</nobr></td>
<td><nobr> - </nobr></td>
<td width="100%"><nobr>xllist.c</nobr></td>
</tr>
</tbody></table></p>
<h2>Syntax</h2>
<dl>
<dt>(rplaca <i>list expr</i>)</dt>
<dd><i>list</i> - the list to destructively modify<br>
<i>expr</i> - the expression to replace <a href="car.htm">car</a>
of <i>list</i><br>
returns - the list node after updating the
<a href="car.htm">car</a></dd>
</dl>
<h2>Description</h2>
<p>The 'rplaca' function destructively modifies the
<a href="car.htm">car</a> of 'list' and replaces it with the
'expr'. The destructive aspect of this operation means that the actual
symbol value is used in the list-modifying operations, not a copy. 'list'
must evaluate to a valid list.</p>
<p>An atom or <a href="nil.htm">NIL</a> for 'list' will result in
an error:</p>
<pre class="example">
<font color="#AA0000">error: bad argument type</font>
</pre>
<h2>Examples</h2>
<pre class="example">
(setq a '(1 2 3)) <font color="#008844">; make A with value (1 2 3)</font>
(setq b '(1 2 3)) <font color="#008844">; make B with value (1 2 3)</font>
(setq c a) <font color="#008844">; make C point to A's value</font>
(rplaca a 'new) <font color="#008844">; returns (NEW 2 3)</font>
(print a) <font color="#008844">; prints (NEW 2 3)</font>
<font color="#008844">; note that A is modified</font>
(print b) <font color="#008844">; prints (1 2 3)</font>
<font color="#008844">; note that B is not modified</font>
(print c) <font color="#008844">; prints (NEW 2 3)</font>
<font color="#008844">; note that C is modified too</font>
(setq a '(1 2 3)) <font color="#008844">; reset A to value (1 2 3)</font>
(rplaca a '(the sub list)) <font color="#008844">; returns ((THE SUB LIST) 2 3)</font>
(rplaca '(1 2 3) 'more) <font color="#008844">; returns (MORE 2 3)</font>
(rplaca 'a 'b) <font color="#008844">; error: bad argument type</font>
(rplaca NIL 'b) <font color="#008844">; error: bad argument type</font>
</pre>
<p>See the
<a href="../manual/xlisp-man-017.htm#rplaca">rplaca</a>
function in the <nobr>XLISP 2.0</nobr> manual.</p>
<p><nobr> <a href="#top">Back to Top</nobr></a></p>
<hr>
<a href="../start.htm">Nyquist / XLISP 2.0</a> -
<a href="../manual/contents.htm">Contents</a> |
<a href="../tutorials/tutorials.htm">Tutorials</a> |
<a href="../examples/examples.htm">Examples</a> |
<a href="reference-index.htm">Reference</a>
</body></html>
|
