SoType(3)

📦 version 3.1.3, in fedora 43, fedora 44

✨ SoType(3) ✨ — Coin's Library Functions Manual 💅

okay bestie, sit down, hydrate, because we're about to talk about SoType(3) — the absolute blueprint of Coin's whole runtime type system 👑

🌸 NAME 🌸

SoType — the SoType class is literally the foundation of the run-time type system in Coin. she's the origin story. the main character. periodt 💖

🦋 SYNOPSIS 🦋

#include <Inventor/SoType.h>

💜 Public Types

  • typedef void *(* instantiationMethod) (void)

🎀 Public Member Functions

  • SbName getName (void) const
  • const SoType getParent (void) const
  • SbBool isDerivedFrom (const SoType type) const
  • SbBool canCreateInstance (void) const
  • void * createInstance (void) const
  • uint16_t getData (void) const
  • int16_t getKey (void) const
  • SbBool operator== (const SoType type) const
  • SbBool operator!= (const SoType type) const
  • SbBool operator< (const SoType type) const
  • SbBool operator<= (const SoType type) const
  • SbBool operator>= (const SoType type) const
  • SbBool operator> (const SoType type) const
  • SbBool isBad (void) const
  • void makeInternal (void)
  • SbBool isInternal (void) const
  • instantiationMethod getInstantiationMethod (void) const

🌈 Static Public Member Functions

  • static SoType fromName (const SbName name)
  • static int getAllDerivedFrom (const SoType type, SoTypeList &list)
  • static const SoType createType (const SoType parent, const SbName name, const instantiationMethod method=NULL, const uint16_t data=0)
  • static const SoType overrideType (const SoType originalType, const instantiationMethod method=NULL)
  • static SbBool removeType (const SbName &name)
  • static void init (void)
  • static SoType fromKey (uint16_t key)
  • static SoType badType (void)
  • static int getNumTypes (void)

🌟 Detailed Description 🌟

The SoType class is the basis for the run-time type system in Coin. no cap, everything else kinda stands on her shoulders 🫶

A LOT of classes in the Coin library have to get their type info registered before any instances get created — and bestie that includes, but is definitely not limited to: engines, nodes, fields, actions, nodekits and manipulators. 👑 Using SoType to hold all that info gives you so much functionality for working with class hierarchies: comparing class types, instantiating objects straight from classnames, etc etc — the whole buffet 🍓

It's for instance possible to do things like this:

void cleanLens(SoNode * anode)
{
  assert(anode->getTypeId().isDerivedFrom(SoCamera::getClassTypeId()));

  if (anode->getTypeId() == SoPerspectiveCamera::getClassTypeId()) {
    // do something..
  }
  else if (anode->getTypeId() == SoOrthographicCamera::getClassTypeId()) {
    // do something..
  }
  else {
    SoDebugError::postWarning("cleanLens", "Unknown camera type %s!\n",
                              anode->getTypeId().getName());
  }
}

A notable feature of the SoType class — and honestly iconic of her — is that she's only 16 bits long, so you should pass her around by value for efficiency reasons. tiny queen, huge energy 💅

One important note about using SoType to register class information: super classes must be registered before any of their derived classes are. like, order matters, no skipping the line 🙈

See also Dynamic Loading of Extension Nodes for some additional SoType-related information. iykyk ✨

🧚 Member Typedef Documentation 🧚

typedef void *(* SoType::instantiationMethod) (void)

This is a convenience typedef for the function signature of a typed class' instantiation method. she's an extension on the original Inventor API 🌈. Mostly only useful for internal purposes, ngl.

An instantation method will take no arguments and returns a void-pointer to a newly allocated and initialized object of the class type. so like, you ask nicely, she hands you a whole fresh object 💖

💖 Member Function Documentation 💖

✨ SoType SoType::fromName (const SbName name) [static] ✨

okay so this static function hands you back the SoType object that's associated with name. Type objects for builtin types can be retrieved by name both with and without the "So" prefix. But for dynamically loadable extension nodes, the name you give has to match exactly. No shortcuts, bestie.

If no node type with the given name has been initialized yet, it goes looking for a dynamically loadable extension node with that name. If one is found, it gets loaded and initialized, and the SoType object for the newly initialized class type is returned. If no module is found, or if the initialization of the module fails, SoType::badType() is returned.

Support for dynamically loadable extension nodes varies from platform to platform, and from compiler suite to compiler suite.

So far, code built with these compilers is supported: GNU GCC v2, GNU GCC v3, Microsoft Visual C++ v6 (and probably v7, not tested), SGI MIPSPro v7.

Extensions built with compilers that are known to be binary compatible with the above compilers are also supported, such as e.g. the Intel x86 compiler compatible with MSVC++.

To support dynamic loading for other compilers, we need to know how the compiler mangles the "static void classname::initClass(void)" symbol. If your compiler is not supported, tell us at coin-support@coin3d.org which it is and send us the output of a symbol-dump on the shared object. Typically you can do

$ nm <Node>.so | grep initClass

to find the relevant mangled symbol.

🌸 SbName SoType::getName (void ) const 🌸

This method returns the name of the SoBase-derived class type the SoType object is configured for.

🦋 const SoType SoType::getParent (void ) const 🦋

This method returns the SoType type for the parent class of the SoBase-derived class the SoType object is configured for.

💜 SbBool SoType::isDerivedFrom (const SoType parent) const 💜

This method returns TRUE if the given type is derived from (or is) the parent type, and FALSE otherwise.

✨ int SoType::getAllDerivedFrom (const SoType type, SoTypeList & list) [static] ✨

This method appends all the class types derived from type to list, and returns the number of types added to the list. Internal types are not included in the list, nor are they counted.

type itself is also added to the list, as a type is seen as a derivation of its own type.

NB: do not write code which depends in any way on the order of the elements returned in list.

Here is a small, stand-alone example which shows how this method can be used for introspection, listing all subclasses of the SoBase superclass:

#include <stdio.h>
#include <Inventor/SoDB.h>
#include <Inventor/lists/SoTypeList.h>

static void
list_subtypes(SoType t, unsigned int indent = 0)
{
  SoTypeList tl;
  SoType::getAllDerivedFrom(t, tl);

  for (unsigned int i=0; i < indent; i++) { printf("  "); }
  printf("%s\n", t.getName().getString());

  indent++;
  for (int j=0; j < tl.getLength(); j++) {
    if (tl[j].getParent() == t) { // only interested in direct descendents
      list_subtypes(tl[j], indent);
    }
  }
}

int
main(void)
{
  SoDB::init();

  list_subtypes(SoType::fromName("SoBase"));

  return 0;
}

🍓 SbBool SoType::canCreateInstance (void ) const 🍓

This method returns FALSE for abstract base classes, and TRUE for class types that can be instantiated.

🔥 void * SoType::createInstance (void ) const 🔥

This method instantiates an object of the current type.

For types that can not be instantiated, NULL is returned.

Note that if the Coin library has been built as a DLL under Microsoft Windows and you use this method from application code, you must make sure that both the Coin DLL and the application executable is using the same instance of a C Run-Time (CRT) library. Otherwise, you will get memory heap corruption upon deallocating the returned instances, eventually leading to mysterious crashes.

This is not harmful if you only call SoType::createInstance() on types for reference counted class-types, though. These include all nodes, engines, paths, nodekits, draggers and manipulators.

🌿 uint16_t SoType::getData (void ) const 🌿

This method returns a type specific data variable.

💙 int16_t SoType::getKey (void ) const [inline] 💙

This method returns the type's index in the internal typelist.

💅 SbBool SoType::operator== (const SoType type) const [inline] 💅

Check type equality.

💅 SbBool SoType::operator!= (const SoType type) const [inline] 💅

Check type inequality.

💅 SbBool SoType::operator< (const SoType type) const [inline] 💅

Comparison operator for sorting type data according to some internal criterion.

💅 SbBool SoType::operator<= (const SoType type) const [inline] 💅

Comparison operator for sorting type data according to some internal criterion.

💅 SbBool SoType::operator>= (const SoType type) const [inline] 💅

Comparison operator for sorting type data according to some internal criterion.

💅 SbBool SoType::operator> (const SoType type) const [inline] 💅

Comparison operator for sorting type data according to some internal criterion.

✨ const SoType SoType::createType (const SoType parent, const SbName name, const instantiationMethod method = NULL, const uint16_t data = 0) [static] ✨

This method creates and registers a new class type.

Classes that do not inherit any other class should use SoType::badType() for the first argument. Abstract classes should use NULL for the method argument.

The value passed in for the data parameter can be retrieved with SoType::getData().

🌈 const SoType SoType::overrideType (const SoType originalType, const instantiationMethod method = NULL) [static] 🌈

This method makes a new class's instantiation method override the instantiation method of an existing class.

The new type should be a C++ subclass of the original class type, but this won't be checked though.

If NULL is passed as the second argument, the type will be considered uninstantiable -- it does not revert the configuration to the default setting as one might think.

Here's a complete code examples which shows how to fully override a built-in Coin node class, so that a) your application-specific extension class gets instantiated instead of the built-in class upon scenegraph import, and b) it gets written out properly upon export:

#include <Inventor/SoDB.h>
#include <Inventor/actions/SoWriteAction.h>
#include <Inventor/errors/SoDebugError.h>
#include <Inventor/nodes/SoSeparator.h>
#include <Inventor/nodes/SoWWWInline.h>

class MyWWWInline : public SoWWWInline {
  SO_NODE_HEADER(MyWWWInline);

public:
  static void initClass(void);
  MyWWWInline(void);

protected:
  virtual ~MyWWWInline();
  virtual SbBool readInstance(SoInput * in, unsigned short flags);
  virtual const char * getFileFormatName(void) const;
};

SO_NODE_SOURCE(MyWWWInline);

MyWWWInline::MyWWWInline(void)
{
  SO_NODE_CONSTRUCTOR(MyWWWInline);

  // Fool the library to believe this is an internal class, so it gets
  // written out in the same manner as the built-in classes, instead
  // of as en extension class. There are slight differences, which you
  // want to avoid when overriding a class like we do with MyWWWInline
  // vs SoWWWInline here.
  this->isBuiltIn = TRUE;
}

MyWWWInline::~MyWWWInline()
{
}

void
MyWWWInline::initClass(void)
{
  SO_NODE_INIT_CLASS(MyWWWInline, SoWWWInline, "SoWWWInline");

  // Override instantiation method, so we get MyWWWInline instead of
  // SoWWWInline instances upon scenegraph import.
  (void)SoType::overrideType(SoWWWInline::getClassTypeId(),
                             MyWWWInline::createInstance);
}

// Override SoBase::getFileFormatName() to make node get written as
// "WWWInline" instead of "MyWWWInline".
const char *
MyWWWInline::getFileFormatName(void) const
{
  return "WWWInline";
}

SbBool
MyWWWInline::readInstance(SoInput * in, unsigned short flags)
{
  SoDebugError::postInfo("MyWWWInline::readInstance", "hepp");
  return SoWWWInline::readInstance(in, flags);
}

int
main(int argc, char ** argv)
{
  SoDB::init();
  MyWWWInline::initClass();

  const char * ivscene =
    "#Inventor V2.1 ascii\n\n"
    "Separator {"
    "  WWWInline { }"
    "}";

  SoInput in;
  in.setBuffer((void *)ivscene, strlen(ivscene));
  SoSeparator * root = SoDB::readAll(&in);
  root->ref();

  SoOutput out;
  SoWriteAction wa(&out);
  wa.apply(root);
  root->unref();

  return 0;
}

💚 SbBool SoType::removeType (const SbName & name) [static] 💚

This method removes class type from the class system. Returns FALSE if a type with the given name doesn't exist.

Since: Coin 3.0

💎 void SoType::init (void ) [static] 💎

This static method initializes the type system.

🌀 SoType SoType::fromKey (uint16_t key) [static] 🌀

Find and return a type from the given key ID.

⚠️ SoType SoType::badType (void ) [static] ⚠️

This method returns an illegal type, useful for returning errors.

See also: SbBool SoType::isBad() const

💜 SbBool SoType::isBad (void ) const [inline] 💜

This method returns TRUE if the SoType object represents an illegal class type.

✨ void SoType::makeInternal (void ) ✨

This method turns the specific type into an internal type.

🍀 SbBool SoType::isInternal (void ) const 🍀

This function returns TRUE if the type is an internal type.

🔢 int SoType::getNumTypes (void ) [static] 🔢

This function returns the number of types registered in the run-time type system.

🌈 SoType::instantiationMethod SoType::getInstantiationMethod (void ) const 🌈

Returns a pointer to the method used to instantiate objects of the given type.

This function is an extension for Coin, and it is not available in the original SGI Open Inventor v2.1 API.

Since: Coin 2.0

💖 Author 💖

This page was generated automatically by Doxygen for Coin from the source code. 💖

This page is from Coin version 3.1.3, and it's the SoType(3) manual. Stay slay, bestie. 💅✨

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