On 30 Jan 2006, at 23:55, Stefan Seefeld wrote:
Stefan Roiser wrote:
Reflex code for this would look something like
Type t = Type::ByName("foo"); Object instance = t.Construct();
That clearly only works if 'foo' has a default constructor, right ?
You are right, the above code snippet has a lot of assumptions (e.g. we found a dictionary for type foo, foo has a default constructor etc.), please see below for a bit more safe implementation.
Even then, it may involve some other resources to be set up. So, what knowledge of the code being invoked that way do you require ?
Reflex would need a dictionary for class "foo" (generated by genreflex.py with gccxml). So something like python genreflex.py foo.h --gccxmlpath=/path/to/gccxml/bin will generate a file foo_rflx.cpp with the dictionary information about class foo. This file will contain all the information necessary to introspect/ interact with foo and can be compiled into a shared library libfoo.so
Who would provide the implementation for 'foo', who would provide the above lines, and who would finally execute them ?
I'm assuming that class foo is a class for which the dictionary is generated and subsequently a user want's to introspect/interact with its dictionary information. So a bit more safe implementation of the lines above would be // load dynamically library libfoo.so Type t = Type::ByName("foo"); if (t && t.IsClass()) { // we found the dictionary information for "foo" and it's a class // let's try to call the default constructor // Construct has several default arguments, by default it will try to invoke the default constructor Object instance = t.Construct(); if (instance) { // we have a valid instance (memory allocated, type associated) // we have constructed an instance through the default constructor } else { // this class does not have a default constructor // let's loop over all constructors and look for one which takes e.g. one int as argument for (Member_iterator mi = t.FunctionMember_Begin(); mi != t.FunctionMember_End(); ++mi) { if ((*mi).IsConstructor()) { Type constType = (*mi).TypeOf(); if (constType.FunctionParameterSize() == 1 && constType.FunctionParameterAt(0).TypeOf().Name() == "int") { // let's invoke this constructor with one argument (this has to be passed in a vector<void*>) int arg0 = 111; std::vector<void*> args; args.push_back(&arg0); instance = t.Construct(constType,args); ....... Cheers Stefan -- Stefan Roiser CERN, PH Department CH - 1211 Geneva 23 Mob:+41 76 487 5334 Tel:+41 22 767 4838 Fax:+41 22 767 9425