Changes between Initial Version and Version 1 of pjsua2/SWIG_Quirks

Timestamp:

Jul 19, 2012 7:12:58 AM (12 years ago)

Author:

bennylp

Comment:

--

pjsua2/SWIG_Quirks

@@ +1 @@
+{{{
+#!html
+<!-- MAIN TABLE START -->
+<table border=0 width="90%" align="center"><tr><td>
+}}}
+
+= SWIG Quirks =
+
+[[TracNav(pjsua2/TOC)]]
+
+'''Table of Contents'''
+[[PageOutline(2-3,,inline)]]
+
+
+[[BR]]
+
+== SWIG Quirks ==
+
+=== Quirks with the use of namespace ===
+
+my_array1 and my_array2 below are not recognized as vector of string:
+
+  {{{
+// example.h
+namespace pj
+{
+  using std::vector;
+  using std::string;
+
+  vector<string> my_array1;          // this is recognized as pj::vector<pj::string>
+  vector<std::string> my_array2;     // this is recognized as pj::vector<std::string>
+}
+  }}}
+
+It works after adding ''std'':
+{{{
+   using std::vector;
+   using std::string;
+   string my_string;                     // ok
+   vector<int> my_array;                 // vector<int> is okay though!
+   std::vector<std::string> my_array;    // now it's ok too
+}}}
+
+=== std::vector as attributes doesn't work as expected ===
+
+Using std::vector as function arguments or return value works fine, e.g.:
+
+  {{{
+// example.h
+class A
+{
+public:
+   void assign_data( const std::vector<int> &data);
+   std::vector<int> retrieve_data() const;
+};
+  }}}
+
+  {{{
+# Python
+import example
+
+a = example.A()
+a.assign_data( [0, 1, 2, 3] )
+data = a.retrieve_data()
+print data
+# will print: [0, 1, 2, 3] as expected
+  }}}
+
+But as class attributes, it doesn't work as expected:
+
+  {{{
+// example.h
+class A
+{
+public:
+    vector<int> my_values;
+};
+   }}}
+
+   {{{
+// example.i
+%module example
+%{
+#include “example.h”
+%}
+
+%include "std_string.i"
+%include "std_vector.i"
+
+namespace std
+{
+        %template(IntVector) std::vector<int>;
+}
+
+%include “example.h”
+   }}}
+
+   {{{
+# Python
+a = example.A()
+a.my_values = [0, 1, 2]                     # <-- ERROR
+a.my_values = example.IntVector([0, 1, 2])  # <-- OK
+   }}}
+
+=== "const" in parameter matters ===
+
+Otherwise conversion from Python list to std::vector doesn't work. E.g.:
+
+ {{{
+// example.h
+class A
+{
+  public:
+        void func_a( const vector<int> & param );
+        void func_b( vector<int> & param );
+};
+ }}}
+
+ {{{
+a.func_a( [0, 1, 2] )        # <-- OK
+a.func_b( [0, 1, 2] )        # <-- ERROR
+ }}}
+
+=== Must use exception specification in C++ functions ===
+
+Otherwise SWIG will terminate the app when it catches unspecified exception. E.g.:
+
+ {{{
+// example.h
+void raise_1() throw(Error)
+{
+   throw Error();
+}
+
+void raise_2()
+{
+   throw Error()
+}
+ }}}
+
+ {{{
+ # Python
+ try:
+    raise_1()
+ except Error, e:
+    pass               # <-- OK
+
+ try:
+    raise_2()          # <-- ERROR (SWIG terminates app), even with catch-anything
+ except:
+    pass
+ }}}
+
+=== Undeclared types will be (silently) converted to pointer ===
+
+Yes we know that, but it will catch you anyway, so I'll mention it again here.
+
+ {{{
+// example.h
+#include <pj/types.h>
+
+class Error
+{
+public:
+    pj_status_t   status;
+    string        reason;
+
+    Error(pj_status_t err, const string &res) : status(err), reason(res) {}
+};
+ }}}
+
+  {{{
+// example.i
+%module example
+%{
+#include “example.h”
+%}
+%include “example.h”
+  }}}
+
+ {{{
+# test.py
+err = pj.Error(-1, "Unknown error")
+print "%d" % err.status
+ }}}
+
+The code above compiles fine, but pj_status_t will be treated as pointer to unknown structure by SWIG, because the declaration is in <pj/types.h> which is not included in example.i. Hence the Python code above will not print -1 but the pointer value of status.
+
+
+=== Java attributes: none of them! === #javaattr
+
+C++ attributes will be converted to get/set functions in Java! E.g.:
+
+ {{{
+// example.h
+class A
+{
+public:
+   int data;
+};
+ }}}
+
+The "data" member will be converted to "getData()" and "setData()" in Java.
+
+
+{{{
+#!html
+<!-- MAIN TABLE END -->
+</td></tr></table>
+}}}
+
+
+
+
+{{{
+#!html
+<!-- MAIN TABLE END -->
+</td></tr></table>
+}}}
+