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
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<!--Converted with LaTeX2HTML 2002-2-1 (1.70)
original version by: Nikos Drakos, CBLU, University of Leeds
* revised and updated by: Marcus Hennecke, Ross Moore, Herb Swan
* with significant contributions from:
Jens Lippmann, Marek Rouchal, Martin Wilck and others -->
<HTML>
<HEAD>
<TITLE>Opaque</TITLE>
<META NAME="description" CONTENT="Opaque">
<META NAME="keywords" CONTENT="users_guide">
<META NAME="resource-type" CONTENT="document">
<META NAME="distribution" CONTENT="global">
<META NAME="Generator" CONTENT="LaTeX2HTML v2002-2-1">
<META HTTP-EQUIV="Content-Style-Type" CONTENT="text/css">
<LINK REL="STYLESHEET" HREF="users_guide.css">
<LINK REL="next" HREF="node58.html">
<LINK REL="previous" HREF="node56.html">
<LINK REL="up" HREF="node54.html">
<LINK REL="next" HREF="node58.html">
</HEAD>
<BODY >
<DIV CLASS="navigation"><!--Navigation Panel-->
<A NAME="tex2html1472"
HREF="node58.html">
<IMG WIDTH="37" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="next" SRC="next.png"></A>
<A NAME="tex2html1466"
HREF="node54.html">
<IMG WIDTH="26" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="up" SRC="up.png"></A>
<A NAME="tex2html1460"
HREF="node56.html">
<IMG WIDTH="63" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="previous" SRC="prev.png"></A>
<A NAME="tex2html1468"
HREF="node14.html">
<IMG WIDTH="65" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="contents" SRC="contents.png"></A>
<A NAME="tex2html1470"
HREF="node317.html">
<IMG WIDTH="43" HEIGHT="24" ALIGN="BOTTOM" BORDER="0" ALT="index" SRC="index.png"></A>
<BR>
<B> Next:</B> <A NAME="tex2html1473"
HREF="node58.html">Enumerations</A>
<B> Up:</B> <A NAME="tex2html1467"
HREF="node54.html">Fundamental Types</A>
<B> Previous:</B> <A NAME="tex2html1461"
HREF="node56.html">Strings</A>
<B> <A NAME="tex2html1469"
HREF="node14.html">Contents</A></B>
<B> <A NAME="tex2html1471"
HREF="node317.html">Index</A></B>
<BR>
<BR></DIV>
<!--End of Navigation Panel-->
<H2><A NAME="SECTION02433000000000000000"></A><A NAME="ssec:basics:fundamental:opaque"></A><A NAME="2175"></A><A NAME="2176"></A>
<BR>
Opaque
</H2>
<P>
The <TT><I CLASS="slanted">opaque</I></TT> type is dangerous, and rarely useful. However,
there are particular times when an opaque type is the only
way to solve a problem. When a SIDL file uses an
<TT><I CLASS="slanted">opaque</I></TT> type, Babel guarantees only bits will be
relayed exactly between caller and callee. If there is a need
to pass more information than an opaque provides, than the
developer can simply pass a pointer to that information.
<P>
Use of a <TT><I CLASS="slanted">opaque</I></TT> carries a heavy penalty.
When Babel matures enough to support distributed computing,
any method calls with <TT><I CLASS="slanted">opaque</I></TT> in the argument list
(or return type) will be restricted to in-process calls only.
<BR>
<IMG
WIDTH="477" HEIGHT="31" ALIGN="BOTTOM" BORDER="0"
SRC="img12.png"
ALT="\begin{rationale}
Since {\ttfamily\slshape {opaque}\/} is typically used for a p...
...equence of bits has no meaning outside of its own
process space.
\end{rationale}">
<BR>
<P>
<BR><HR>
<ADDRESS>
<br><br>babel-0.10.2<br>users_guide Last Modified 2005-03-23<br><br><a href="http://www.llnl.gov/CASC/components">http://www.llnl.gov/CASC/components</a><br><a href="mailto:components@llnl.gov">components@llnl.gov</a>
</ADDRESS>
</BODY>
</HTML>
|
