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
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
|
<!--
Copyright (c) 2001, 2002, 2003 Steven Knight
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be included
in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
-->
<!--
=head2 Adding new methods
For slightly more demanding changes, you may wish to add new methods to the
C<cons> package. Here's an example of a very simple extension,
C<InstallScript>, which installs a tcl script in a requested location, but
edits the script first to reflect a platform-dependent path that needs to be
installed in the script:
# cons::InstallScript - Create a platform dependent version of a shell
# script by replacing string ``#!your-path-here'' with platform specific
# path $BIN_DIR.
sub cons::InstallScript {
my ($env, $dst, $src) = @_;
Command $env $dst, $src, qq(
sed s+your-path-here+$BIN_DIR+ %< > %>
chmod oug+x %>
);
}
Notice that this method is defined directly in the C<cons> package (by
prefixing the name with C<cons::>). A change made in this manner will be
globally visible to all environments, and could be called as in the
following example:
InstallScript $env "$BIN/foo", "foo.tcl";
For a small improvement in generality, the C<BINDIR> variable could be
passed in as an argument or taken from the construction environment-,-as
C<%BINDIR>.
=head2 Overriding methods
Instead of adding the method to the C<cons> name space, you could define a
new package which inherits existing methods from the C<cons> package and
overrides or adds others. This can be done using Perl's inheritance
mechanisms.
The following example defines a new package C<cons::switch> which
overrides the standard C<Library> method. The overridden method builds
linked library modules, rather than library archives. A new
constructor is provided. Environments created with this constructor
will have the new library method; others won't.
package cons::switch;
BEGIN {@ISA = 'cons'}
sub new {
shift;
bless new cons(@_);
}
sub Library {
my($env) = shift;
my($lib) = shift;
my(@objs) = Objects $env @_;
Command $env $lib, @objs, q(
%LD -r %LDFLAGS %< -o %>
);
}
This functionality could be invoked as in the following example:
$env = new cons::switch(@overrides);
...
Library $env 'lib.o', 'foo.c', 'bar.c';
-->
<para>
X
</para>
<section>
<title>Builders That Execute External Commands</title>
<para>
X
</para>
</section>
<section>
<title>Builders That Execute Python Functions</title>
<para>
X
</para>
</section>
|
