casacore
DefaultValue.h
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1//# DefaultValue.h: fill a variable with its default value.
2//# Copyright (C) 1995,1996,2000
3//# Associated Universities, Inc. Washington DC, USA.
4//#
5//# This library is free software; you can redistribute it and/or modify it
6//# under the terms of the GNU Library General Public License as published by
7//# the Free Software Foundation; either version 2 of the License, or (at your
8//# option) any later version.
9//#
10//# This library is distributed in the hope that it will be useful, but WITHOUT
11//# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12//# FITNESS FOR A PARTICULAR PURPOSE. See the GNU Library General Public
13//# License for more details.
14//#
15//# You should have received a copy of the GNU Library General Public License
16//# along with this library; if not, write to the Free Software Foundation,
17//# Inc., 675 Massachusetts Ave, Cambridge, MA 02139, USA.
18//#
19//# Correspondence concerning AIPS++ should be addressed as follows:
20//# Internet email: aips2-request@nrao.edu.
21//# Postal address: AIPS++ Project Office
22//# National Radio Astronomy Observatory
23//# 520 Edgemont Road
24//# Charlottesville, VA 22903-2475 USA
25//#
26//#
27//# $Id$
28
29#ifndef CASA_DEFAULTVALUE_H
30#define CASA_DEFAULTVALUE_H
31
32#include <casacore/casa/aips.h>
33
34namespace casacore { //# NAMESPACE CASACORE - BEGIN
35
36// <summary>
37// A templated function which sets a variable to a default value.
38// </summary>
39
40// <use visibility=export>
41
42// <reviewed reviewer="syang" date="1996/03/14" tests="tDefaultValue.cc" demos="">
43// </reviewed>
44
45// <prerequisite>
46// </prerequisite>
47//
48// <etymology>
49// The DefaultValue function name is derived from its use to fill a data type
50// with a default value, usually zero.
51// </etymology>
52//
53// <synopsis>
54// The DefaultValue function is passed an instance of a data type and the
55// variable is filled with a default value. The majority of classes may
56// use the templated version here. Special classes may use their own
57// non-templated specializations as demonstrated in
58// ../Utilities/test/tDefaultValue.cc.
59// </synopsis>
60//
61// <example>
62// <srcblock>
63// Int foo = 35;
64// defaultValue(foo);
65// AlwaysAssert(foo == 0, AipsError);
66// Array<Float> bar;
67// defaultValue(bar);
68// AlwaysAssert(allEQ(bar, 0.0f), AipsError);
69// </srcblock>
70// A special class may need its own implementation:
71// <srcblock>
72// void defaultValue(MySpecialClass &val){
73// // make a default value be all zeros
74// val.operator()(IPosition(2,3,4)) = Table.keywords().defaultval();
75// };
76// </srcblock>
77// </example>
78//
79// <motivation>
80// We needed a common way of setting all objects to zero or some
81// null/default value. Specializing a templated function seemed the only way
82// to reach everyone.
83// </motivation>
84//
85// <templating arg=T>
86// <li> constructor T(Int)
87// <li> assignment operator (copy semantics)
88// </templating>
89//
90// <thrown>
91// <li> none
92// </thrown>
93//
94// <todo asof="1996/02/22">
95// <li> none
96// </todo>
97
98// <group name=defval>
100template <class T> inline void defaultValue(T &theValue)
101{
102 theValue = T(0);
103}
104
105// </group>
106
107
108} //# NAMESPACE CASACORE - END
109
110#endif
this file contains all the compiler specific defines
Definition: mainpage.dox:28