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| 52 | <H1><A NAME="SECTION006300000000000000000"></A><A NAME="win-dlls"></A> |
| 53 | <BR> |
| 54 | 4.3 Using DLLs in Practice |
| 55 | </H1> |
| 56 | |
| 57 | <P> |
| 58 | Windows Python is built in Microsoft Visual C++; using other |
| 59 | compilers may or may not work (though Borland seems to). The rest of |
| 60 | this section is MSVC++ specific. |
| 61 | |
| 62 | <P> |
| 63 | When creating DLLs in Windows, you must pass <span class="file">pythonXY.lib</span> to |
| 64 | the linker. To build two DLLs, spam and ni (which uses C functions |
| 65 | found in spam), you could use these commands: |
| 66 | |
| 67 | <P> |
| 68 | <div class="verbatim"><pre> |
| 69 | cl /LD /I/python/include spam.c ../libs/pythonXY.lib |
| 70 | cl /LD /I/python/include ni.c spam.lib ../libs/pythonXY.lib |
| 71 | </pre></div> |
| 72 | |
| 73 | <P> |
| 74 | The first command created three files: <span class="file">spam.obj</span>, |
| 75 | <span class="file">spam.dll</span> and <span class="file">spam.lib</span>. <span class="file">Spam.dll</span> does not contain |
| 76 | any Python functions (such as <tt class="cfunction">PyArg_ParseTuple()</tt>), but it |
| 77 | does know how to find the Python code thanks to <span class="file">pythonXY.lib</span>. |
| 78 | |
| 79 | <P> |
| 80 | The second command created <span class="file">ni.dll</span> (and <span class="file">.obj</span> and |
| 81 | <span class="file">.lib</span>), which knows how to find the necessary functions from |
| 82 | spam, and also from the Python executable. |
| 83 | |
| 84 | <P> |
| 85 | Not every identifier is exported to the lookup table. If you want any |
| 86 | other modules (including Python) to be able to see your identifiers, |
| 87 | you have to say "<tt class="samp">_declspec(dllexport)</tt>", as in "<tt class="samp">void |
| 88 | _declspec(dllexport) initspam(void)</tt>" or "<tt class="samp">PyObject |
| 89 | _declspec(dllexport) *NiGetSpamData(void)</tt>". |
| 90 | |
| 91 | <P> |
| 92 | Developer Studio will throw in a lot of import libraries that you do |
| 93 | not really need, adding about 100K to your executable. To get rid of |
| 94 | them, use the Project Settings dialog, Link tab, to specify |
| 95 | <em>ignore default libraries</em>. Add the correct |
| 96 | <span class="file">msvcrt<var>xx</var>.lib</span> to the list of libraries. |
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| 131 | <span class="release-info">Release 2.4.2, documentation updated on 28 September 2005.</span> |
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