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diff --git a/swigweb/myths.ht b/swigweb/myths.ht deleted file mode 100644 index 2a261e773..000000000 --- a/swigweb/myths.ht +++ /dev/null @@ -1,224 +0,0 @@ -SWIG Myths - -<p> -<h2>SWIG Myths</h2> - -<p> -Here are some common misconceptions about SWIG that have occasionally -appeared on other web pages and in articles--especially those that -describe older SWIG versions. - -<font color="#ff0000"><h4>Myth: SWIG only really works with ANSI C</h4></font> - -<h4>Fact:</h4> - -SWIG <em>does</em> provide wrapping support for all of ANSI C. However, SWIG has -also included C++ support since its initial release in 1996. To be fair, early -SWIG releases had limitations, but C++ support has continually improved with -each SWIG release. - -<p> -C++ support in current SWIG releases is quite advanced--providing support for nearly -every C++ feature including templates, namespaces, operators, overloaded methods, -and more. The only major C++ feature not supported is nested classes---and we're -working on that. See the <a href="compare.html">Features</a> page for more information. - -<font color="#ff0000"><h4>Myth: SWIG wraps C++ into this unusable -low-level "C-tran" interface.</h4></font> - -<h4>Fact:</h4> - -When wrapping C++, SWIG <em>does</em> generate a set of low-level procedural -wrappers. However, these are only used as building blocks for -creating a more advanced high-level wrappers (in fact, users rarely -interact with this layer directly). In nearly all target languages, -SWIG wraps C++ classes into a nice object-oriented interface that -mirrors the underlying C++ code. In Python, C++ classes -are wrapped as Python classes, in Perl, C++ classes are wrapped as -Perl classes, and so forth. The existence of procedural wrappers is -only an artifact of SWIG's layered approach to wrapper code generation. - -<font color="#ff0000"><h4>Myth: SWIG doesn't support overloaded methods/functions</h4></font> - -<h4>Fact:</h4> - -SWIG provides full support for C++ overloaded methods and functions. -For example, if you have declarations like this: - -<blockquote> -<pre> -class Foo { -public: - Foo(); - Foo(const Foo &); - void spam(int x); - void spam(double x); - void spam(char *x, int n); -}; -</pre> -</blockquote> - -They can be used in a completely natural way from most SWIG language modules. For example, -in Python: - -<blockquote> -<pre> ->>> f = Foo() ->>> f.spam(3) ->>> f.spam(3.5) ->>> f.spam("hello",5) ->>> g = Foo(f) # Make a copy -</pre> -</blockquote> - -Or in Tcl: - -<blockquote> -<pre> -% Foo f -% f spam 3 -% f spam 3.5 -% f spam "hello" 5 -% Foo g f -</pre> -</blockquote> - -The SWIG implementation of overloading utilizes type categories and a -type precedence scheme that results in the generation of dynamic -dispatch functions. The order in which declarations appear does not matter nor -does SWIG rely on unreliable mechanisms like trial execution (i.e., trying methods -one by one until one happens to execute successfully). Overloading support in SWIG -is more advanced than that. - -<P> -Due to the dynamic nature of scripting languages, it is not possible to -fully disambiguate overloaded methods to the same degree as in C++. -For example, you might have declarations like this: - -<blockquote> -<pre> -int foo(int); -long foo(long); -</pre> -</blockquote> - -In this case, SWIG provides a number of directives to either rename or ignore -one of the declarations. For example: - -<blockquote> -<pre> -%ignore foo(long); -</pre> -</blockquote> - -or - -<blockquote> -<pre> -%rename(foo_long) foo(long); -</pre> -</blockquote> - -<font color="#ff0000"><h4>Myth: SWIG doesn't support basic idiomatic C++ constructs like templates and smart pointers</h4></font> - -<h4>Fact:</h4> - -SWIG fully supports templates. However, to wrap a template class, you have to -tell SWIG about a particular instantiation. This is easy, just make sure SWIG -knows about the template definition and include a special directive like this: - -<blockquote> -<pre> -%template(deque_int) std::deque<int>; -</pre> -</blockquote> - -In this case, "deque_int" becomes the target language name for the wrapped object. -You would use it just like a normal class in the extension module: - -<blockquote> -<pre> ->>> d = deque_int(100) ->>> d.size() -100 ->>> -</pre> -</blockquote> - -On the subject of smart-pointers, those are supported too. For example, suppose -you had some code like this: - -<blockquote> -<pre> -class Foo { -public: - int x; - int spam(int x); -}; - -template<class T> class SmartPtr { -public: - ... - T *operator->(); - ... -}; - -typedef SmartPtr<Foo> FooPtr; - -FooPtr make_Foo(); -</pre> -</blockquote> - -To wrap this with SWIG, just tell it about a template instantiation. For example: - -<blockquote> -<pre> -%template(FooPtr) SmartPtr<Foo>; -</pre> -</blockquote> - -Now, in the target language, the wrapper object works just like you would expect: - -<blockquote> -<pre> ->>> f = make_Foo() ->>> f.x = 3 ->>> f.spam(42) -</pre> -</blockquote> - - -<font color="#ff0000"><h4>Myth: SWIG is just too confusing to use</h4></font> - -<h4>Fact:</h4> - -Most users find SWIG to be relatively easy to use. However, confusion can arise -from the following: - -<ul> -<li>C programming. To effectively use SWIG, you should have a good grasp of -basic C programming concepts like pointers, arrays, memory management, data structures, -functions, parameter passing semantics, and so forth. SWIG tries to make it easy for -C programmers to build extension modules, but it does not try to make C programming -easy. - -<p> -<li>C++. This language is so large and complicated that certain parts of SWIG -may not make any sense unless you are also familiar with the underlying C++ concepts. - -<P> -<li>Dynamic linking and shared libraries. To build extension modules, you usually -have to create DLLs. If you've never done this before, there is a small -learning curve associated with finding the right compiler and linker options. - -<p> -<li>Customization features. SWIG provides a large number of customization features and -options that can be used to control almost all parts of the wrapper generation -process. These are provided to better support power users and to provide the -flexibility needed to solve difficult real-world wrapping problems. However, -none of this is needed to get started. - -</ul> - - - |