SWIG TO-DO Release: SWIG-1.3.19 $Header$ ----------------------------------------------------------------------------- **** = High Priority *** = Implement if possible. ** = Will implement if time. * = Implement if bored (or deemed necessary). defer = Implement in next version CORE: **** Add support for nested classes. The type system should be defer ready to go. The primary obstacle lies in the target language modules (which were never programmed with nested classes in mind). There are also issues with nested C structures. For example: struct Foo { struct { int x,y; } z; }; This is one of the last remaining "hard" problems in the SWIG core, but it is important that we solve it. **** Typemap environments. Stay tuned. [DONE] Merge "in" and "ignore" typemaps into a single "in" typemap. This would solve a variety of subtle problems with multiple argument typemaps and other typemap code. I propose to merge the typemaps by making "ignore" a typemap attribute. For example: %typemap(in,ignore="1") int *OUTPUT (int temp) { $1 = &temp; } This merging makes a lot of sense because "in" and "ignore" typemaps both deal with input argument handling and they are meant to be mutually exclusive of each other. By unifying into a single typemap, you fix the mutual exclusion problem (since there is only one typemap). I also think it makes more sense to think of an "ignored" argument as a input value property. Update: Matthias proposes a generalization in which the number of input arguments could be specified. For example: %typemap(in,numinputs="0") int *OUTPUT (int temp) { $1 = &temp; } This seems to be a better solution. **** Implement "throws" typemaps for all of the target languages. Partly implemented for Tcl, Perl, Python, Ruby, Java. *** "Nested" typemaps. The basic idea is similar to allowing one to use $descriptor(T) for any T, rather than just $descriptor for the type currently being typemapped. In short (ha!), given a previously defined typemap: %typemap(in) Foo { // whatever it takes to initialize $1 from $input } it would be possible to inline its code inside another typemap. While the syntax is still to be defined, the use would be along the lines of: template class vector { %typemap(in) vector { ... for (int i=0; i $typemap(in, input=x) ( int FIRST = foo, double SECOND = bar ); The advantage of this syntax would be that the formal arguments (int FIRST, double SECOND) are close to the actual arguments (foo, bar). Comment by beazley $typemap(in, input=x) int = foo; is a little bit hard to parse in terms of variable substitution. I'm considering something like this: $typemap(in,1=int foo, input=x) *** Add attributes to the %feature directive. Something like: %feature("except", throws="OutOfMemoryException") *** Implement $fail special variable substitution in wrappers. Used to properly transfer control out of a wrapper function while reclaiming resources. *** Better targeting of output typemaps. For example: It is not possible to target an output typemap for function Foo::func() and not Bar::func(). Output typemaps need to support syntax something along the lines of: %typemap(out) int *Foo::func { ... } *** Rewrite declaration annotation to better unify %rename and related directives. Add a selector mechanism that allows specific parse tree nodes to be identified. For example: %feature("foo", nodetype="class") Foo { ... some code ... }; Also desirable for the Java module to specify the classes to go in the throw clause: %feature("except", throws="OutOfMemoryException") Foo { ... code which throws the OutOfMemoryException ... }; Consider use of wildcards. Namespace/nested scope support in %feature is currently weak. It works, but is fragile. Consider an implementation that is better integrated with symbol table management. Continue to consolidate SWIG directives to %feature. *** Bring Aquinas' contract/assertion checking code online. *** Add more intelligent information related to object ownership. SWIG should be able to automatically strip ownership from objects when they are assigned to pointer variables and structure members as well as stored in a container (i.e., an array of pointers). [ Partially finished for Tcl/Python. ] [DONE] Modify smart pointer handling to properly handle inheritance. For example: %ignore Foo; class Foo { public: Blah *operator->(); }; class Bar : public Foo { } Bar should still allow access to Blah * through operator->(). [DONE] Virtual function optimization. If you have two classes like this: class Foo { public: virtual int blah(int); }; class Bar : public Foo { public: virtual int blah(int); }; Then SWIG ought to be able to reuse the wrapper for Foo::blah as Bar::blah. This should result in much smaller extension modules. This feature is now enabled using the -fvirtual option. ** Restoration of the documentation system. ** Restoration of Objective-C support. ** Unification of symbol tables and type system scopes. In a sense they capture the same information so it is not necessary to have both. The existence of two symbol management systems is mostly historical. ** Add a warning for uninstantiated templates. For example, if a function using a template type, but that type hasn't been instantiated using %template. * Fix template partial specialization matching rules. SWIG does not implement the proper C++ type deduction rules, but it does handle the most common cases. This is likely to be hard and implementing it would really only be for completeness. Build ----- **** Make sure there are tests for *ALL* library files in the test-suite. A number of files appear to be broken in SWIG-1.3.13. [DONE] Move the Source/Modules1.1 directory into the Source/Modules directory and deprecate Modules1.1. Library ------- **** Add more support for the C++ standard library. std::complex and other core datatypes. Refine support for STL vector. Add more STL objects. **** Continue to expand the set of recognized typemaps. Windows ------- *** VC++ Project files / Makefiles for building the runtime libraries. Will require libtool mods to work under Cygwin. All language modules -------------------- Python ------ *** Ability to wrap certain classes as Python built-in types. Perl ---- **** Rewrite runtime pointer type checking to better integrate shadow classes. Creation of shadow classes should be done in C instead of Perl. This will fix a number of problems related to typemaps and reduce the amount of Perl wrapper code. **** Create tests for existing support for operator overloading Tcl --- Ruby ---- **** Add Ruby support for Mark Rose's polymorphism code. **** The "Resource Management in Proxies" section of the "SWIG and C++" chapter discusses how proxies' ownership of their associated C++ object can change, and the use of the special disown() and acquire() methods to change this ownership status. Need to address this for Ruby as well. [DONE] Investigate the new object allocation framework that has been implemented for Ruby 1.8 and determine what (if anything) needs to be changed for the wrapper code generated by SWIG. For background see ruby-talk messages 23358 and 38856 (and related threads). *** Add support for keyword arguments (by collecting them in a hash?). [DONE] Add support for defining nested modules. This should work like it does for the SWIG Perl module. [DONE] In a post to the SWIG users' mailing list (June 5: "Multiple Inheritance and Ruby"), Brett Williams suggested a workaround for supporting multiple inheritance in the Ruby module. I'm quoting it here since the idea may be best implemented at the core level for reuse by other language modules that have limited support for MI: """ While it makes for longer generated wrapper code, you can easily generate wrappers as Ruby methods on the derived class in these cases, i.e.: class Base1; class Base2; class Derived : public Base1, public Base2; class OtherDerived : public Base2; This would mean that for class Derived, the methods for Base2 would be generated as methods on class Derived as opposed to a superclass. For class OtherDerived, things work as normal, and any other derived class from Base2 would still work as they currently are, unless other derived classes also use MI. The exception and extra wrapper generation would only kick in with the use of multiple inheritance where the base class information is available to SWIG. The feature could be turned on and off, and doesn't have to be default if necessary. I was under the impression that the Tcl module, until a few releases ago, did all inheritance this way (generating wrappers for superclass methods in all derived classes). It does bloat the wrapper code, but in this case it would only be causing more bloat in cases where the alternative is no support. What is missing with this? Hmmmm... if Base2 implements a method that is overridden by Derived, then you could not get at Base2::Method() via the super keyword... what else am I missing? Again, the alternative is no support for MI at all unless you want to get fancy with mixins. I'm not sure how good of an idea that is or even if it is workable. """ Another problem (which we can't really get around anyways) is that basic inheritance relationships wouldn't be true at the Ruby level, e.g. Derived#is_a?(Base1) would return true but Derived#is_a?(Base2) would return false. * Add some special directives to automatically rename declarations to or from CamelCase. [DONE] Consider adding a switch to define everything in the global (Kernel) module instead of nested in a user-defined module, but only if it comes up. Java ---- **** Default argument support. Default arguments are effectively ignored at present. An overridden method for each default argument could be generated thereby enabling one to call methods with default arguments. [DONE] Implement idea from Dave Dribin email to the swig mailing list, 2 April 2003, where the global enums and constants are placed in an interface so that they can be implemented by other Java classes. This will allow improved syntax when referring to the enums/constants: int foo = enumname; instead of int foo = ModuleName.enumname; C# -- *** Need a way to throw a C# exception from the PINVOKE C/C++ code. *** The correct override/virtual keywords not always emitted for polymorphic methods. It currently only works when 'virtual' is specified in a derived C++ class function. A polymorphic method need not specify 'virtual' in C++. PHP --- ** When returning wrapped objects via alternate constructors if that pointer value already exists "out there" as a resource we should use the same resource, we can't have multiple ref-counted resources mapping to the same object in case it gets twice destroyed. And check if ref count destroying is even working, see smart_pointer_rename * Work out how classes without even inherited constructors should interact with the php "new " notation. See: abstract_inherit_wrap.cpptest ** Look at pass by point and passby ref, Make sometype** to be auto allocated Make sometype& and sometype* to be autoallocated IF THEY ARE NOT ALREADY swigtype wrapped. * Overloading, callbacks, really review to see what else is missed Guile ----- ** Rename slot setters from CLASS-SLOT-set to CLASS-SLOT-set! to match Scheme convention for naming of mutators. ** Support keyword args. ** Support GOOPS shadow classes. [DONE] Support garbage collection. ** Make SWIG's types first-class by using a separate smob type for SWIG type descriptors; enable reflection on types. (Maybe GOOPS metaclasses?) ** Maybe communicate the type system between object modules via Scheme variables, rather than a shared object. ** Provide a clean way to construct type predicates. Mzscheme -------- ** Port list-vector.i and pointer-in-out.i from Guile. Pike ---- * Decide how to handle global variables (probably using something like the Python module's cvar). Affects Examples/pike/simple. * Decide how to handle static class member functions and member variables. * Should investigate the possibility of generating .cmod files in addition to straight C/C++ code for extensions. Common Lisp ----------- * Random thoughts by mkoeppe on supporting Common Lisp implementations: There are many different Foreign Function Interfaces (FFI) for the various CL implementations. Probably SWIG should interface to UFFI, a least-common-denominator FFI that supports many implementations. Via the s-expression SWIG module we can export SWIG's parse tree and import it into CL. It remains to check if all relevant information is dumped (for instance, the type information). Experimental code is available to generate low-level UFFI declarations from this parse tree. However, for wrapping C++, we also need to create C wrappers because most FFIs cannot directly import C++. A CL SWIG module could be exporting both these wrappers and UFFI declarations. I have experimental code (not checked in yet) that does this. This is fine for generating low-level wrappers. But how do we support user typemaps (like converting lists and vectors to C arrays on input)? We have to generate Lisp code that does the conversion and then calls the low-level wrapper. If we generate Lisp code, it should be beautiful and readable. Therefore, we need at least a Lisp pretty printer. A Lisp pretty printer works best when the Lisp program is represented not as text but as Lisp data. Moreover, typemap writers will feel very much constrained by SWIG's capabilities for generating wrapper code, when compared to writing Lisp macros. Thus we would need half a re-implementation of Lisp in SWIG to make users happy. The solution could be the following: ** Build a SWIG library (again) and load it into a Common Lisp implementation. The FFI declarations could be written manually, or this could be bootstrapped via the s-expression module or the primitive UFFI wrappers. This should be easy because SWIG's API is quite simple. The embedded SWIG would be driven by a CL program. High-level typemaps would be written as Lisp programs that generate Lisp code. Documentation ------------- **** Extending SWIG (and internals). *** Perl, Python, Tcl modules. *** add section for Perl module support for operator overloading ** Add section on WAD. Other ----- ***** Learn more wicked Jazz chords. (in progress)