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Fix %import and %fragment forced inclusion to not generate code.

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William S Fulton 2017-06-03 16:18:41 +01:00
commit 57a89f987d
8 changed files with 186 additions and 7 deletions
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91
Doc/Manual/Typemaps.html
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@ -3904,9 +3904,9 @@ A fragment can use one or more additional fragments, for example:
<div class="code">
<pre>
%fragment("&lt;limits.h&gt;", "header") {
%#include &lt;limits.h&gt;
}
%fragment("&lt;limits.h&gt;", "header") %{
#include &lt;limits.h&gt;
%}
%fragment("AsMyClass", "header", fragment="&lt;limits.h&gt;") {
@ -3989,8 +3989,91 @@ Finally, you can force the inclusion of a fragment at any point in the generated
</div>
<p>
which is very useful inside a template class, for example.
which, for example, is very useful inside a template class.
Another useful case is when using <tt>%extend</tt> inside a class
where the additional code in the <tt>%extend</tt> block depends on the contents of the fragment.
</p>
<div class="code">
<pre>
%fragment("&lt;limits.h&gt;", "header") %{
#include &lt;limits.h&gt;
%}
struct X {
...
%extend {
%fragment("&lt;limits.h&gt;");
bool check(short val) {
if (val &lt; SHRT_MIN /*defined in &lt;limits.h&gt;*/) {
return true;
} else {
return false;
}
}
}
};
</pre>
</div>
<p>
Forced inclusion of fragments can be used as a replacement for <a href="SWIG.html#SWIG_nn42">code insertion block</a>, ensuring the
code block is only generated once.
Consider the contents of FileA.i below which first uses a code insertion block and then a forced fragment inclusion to generate code:
<p>
<div class="code">
<pre>
// FileA.i
%{
#include &lt;stdio.h&gt;
%}
%fragment("&lt;limits.h&gt;");
</pre>
</div>
<p>
and another file including the above:
</p>
<div class="code">
<pre>
// FileB.i
%include "FileA.i"
</pre>
</div>
<p>
The resulting code in the wrappers for FileB.i is:
</p>
<div class="code">
<pre>
#include &lt;stdio.h&gt;
#include &lt;limits.h&gt;
</pre>
</div>
<p>
A note of caution must be mentioned when using <tt>%fragment</tt> forced inclusion or code insertion blocks with <tt>%import</tt>.
If <tt>%import</tt> is used instead:
<p>
<div class="code">
<pre>
// FileC.i
%import "FileA.i"
</pre>
</div>
<p>
then nothing is generated in the resulting code in the wrappers for FileC.i.
This is because <tt>%import</tt> is for collecting type information and does not result in any code
being generated, see <a href="Preprocessor.html#Preprocessor_nn3">File Imports</a>.
</p>
</ol>
<p>