Legacy Code still a thing?

Yakuza

Hi.

I just tried to compile a simple plugin for 2024 whose code basically worked for the last 16 years. Now it throws 40 errors.

Has the time come for an inevitable re-write or should it continue to work and it's just a matter of fixing some stuff?

Cheers

ferdinand

Hello @Yakuza,

Thank you for reaching out to us. 'Rewrite' is a bit too strong word, but the 2024 release comes with significant changes to the API to achieve the speed improvements it does. You can read about the details in the Migrating Plugins to the 2024.0 API guide.

Cheers,
Ferdinand

Yakuza

Thanks Ferdinand, I'll try.

ferdinand

Hey @Yakuza,

It is usually not that bad, things look more complicated than they are. Just ask questions here on Plugin Café when you are stuck on an error, I will nudge you then into the right direction. After a few items you will get the hang of it.

40 errors should be fixable in a few hours at most, including the learning curve.

Cheers,
Ferdinand

Yakuza

@ferdinand

Thank you. It's actually "only" 26 errors on compilation. They are mostly BaseContainer related, to no surprise, since the plugin does largely only handle containers and their values. See console output below.

So if you for starters could nudge me regarding
cannot convert from 'const BaseContainer * to 'BaseContainer* and
cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &
I might be half way done.

Error1 - Lines 51ff look like this

Int32 SOLO::GetState(BaseDocument *doc, GeDialog* parentManager)
{
	BaseContainer *bc = doc->GetDataInstance()->GetContainerInstance(SOLO_ID);
	if (!bc) return CMD_ENABLED;
	else if (bc->GetInt32(ID_SOLO_SET, 0) == 0) return CMD_ENABLED;
	else return CMD_ENABLED | CMD_VALUE;
}

Error3 - Line 181

obj->GetDataInstance()->GetContainerInstance(SOLO_ID)->SetInt32(ID_SOLO_STATE, data);

Any pointers to pointers and constant containers would be welcome.

Cheers,
Bo

Severity Code Description Project File Line Suppression State
Error C2440 'initializing': cannot convert from 'const BaseContainer *' to 'BaseContainer *' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 53
Error C4996 'BaseList2D::GetData': Use GetDataInstanceRef() to avoid the unnecessary BaseContainer copy solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 109
Error C2662 'void BaseContainer::SetInt32(Int32,Int32)': cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 181
Error C2662 'void BaseContainer::SetInt32(Int32,Int32)': cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 182
Error C2662 'void BaseContainer::SetBool(Int32,Bool)': cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 183
Error C4263 'Bool SoloPrefs::Init(GeListNode *)': member function does not override any base class virtual member function solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 133
Error C2662 'void BaseContainer::SetInt32(Int32,Int32)': cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 199
Error C4264 'Bool NodeData::Init(GeListNode *,Bool)': no override available for virtual member function from base 'NodeData'; function is hidden solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 145
Error C4263 'Bool SoloPrefs::GetDParameter(GeListNode *,const DescID &,GeData &,DESCFLAGS_GET &)': member function does not override any base class virtual member function solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 134
Error C2662 'void BaseContainer::SetInt32(Int32,Int32)': cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 200
Error C4264 'Bool NodeData::GetDParameter(const GeListNode *,const DescID &,GeData &,DESCFLAGS_GET &) const': no override available for virtual member function from base 'NodeData'; function is hidden solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 145
Error C4263 'Bool SoloPrefs::GetDEnabling(GeListNode *,const DescID &,const GeData &,DESCFLAGS_ENABLE,const BaseContainer *)': member function does not override any base class virtual member function solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 136
Error C2662 'void BaseContainer::SetBool(Int32,Bool)': cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 201
Error C4264 'Bool NodeData::GetDEnabling(const GeListNode *,const DescID &,const GeData &,DESCFLAGS_ENABLE,const BaseContainer *) const': no override available for virtual member function from base 'NodeData'; function is hidden solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 145
Error C4263 'Bool SoloPrefs::GetDDescription(GeListNode *,Description *,DESCFLAGS_DESC &)': member function does not override any base class virtual member function solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 137
Error C2662 'void BaseContainer::SetInt32(Int32,Int32)': cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 208
Error C4264 'Bool NodeData::GetDDescription(const GeListNode *,Description *,DESCFLAGS_DESC &) const': no override available for virtual member function from base 'NodeData'; function is hidden solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 145
Error C2662 'void BaseContainer::SetInt32(Int32,Int32)': cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 209
Error C2662 'void BaseContainer::SetBool(Int32,Bool)': cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 210
Error C2440 'initializing': cannot convert from 'const BaseContainer *' to 'BaseContainer *' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 228
Error C2662 'void BaseContainer::SetInt32(Int32,Int32)': cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\solo2023.cpp 260
Error C2664 'Bool SoloPrefs::InitValues(const DescID &,Description *)': cannot convert argument 1 from '<unnamed-enum-PREF_SOLOPREFS_MAIN_GROUP>' to 'const DescID &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 209
Error C2440 '<function-style-cast>': cannot convert from 'initializer list' to 'GeData' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 229
Error C2664 'Bool SoloPrefs::InitValues(const DescID &,Description *)': cannot convert argument 1 from '<unnamed-enum-PREF_SOLOPREFS_MAIN_GROUP>' to 'const DescID &' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 271
Error C2440 'initializing': cannot convert from 'const BaseContainer *' to 'BaseContainer *' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 278
Error C2440 '=': cannot convert from 'const BaseContainer *' to 'BaseContainer *' solo2023 D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp 282

ferdinand

Hey @Yakuza,

changes to the mutability, a.k.a., const-ness, of data are the overarching theme of the 2024 changes, if you haven't done it already, I would strongly recommend reading the migration guide. It is split into bite sized chunks so that you only must consume what you need, in this case the most relevant chunk is probably Node Data Container Access.

For your error, you should try (the const-ness of the pointer is optional) this, since you only want to read here:

const BaseContainer* const bc = doc->GetDataInstance()->GetContainerInstance(SOLO_ID);

Cheers,
Ferdinand

Yakuza

Thank you, Ferdinand. Yes, I did that already and changed the first bc to const. Your link says btw.:
" Note -Legacy code will compile and run without adaptions but adhering to these changes will yield performance improvements."

Now there are 10 instances of error 3 above.

ferdinand

Hello @Yakuza,

The note is referring to the BaseList2D data container access methods where 2023 code will indeed compile for 2024. Regarding the rest of your errors, it is a bit hard to infer what is happening in each of them without your code, but I would split them into two groups (there are also other error types in there):

const-ness Violations

E.g.:

Error C2662 'void BaseContainer::SetInt32(Int32,Int32)': cannot convert 'this' pointer from 'const BaseContainer' to 'BaseContainer &' solo2023 ...\solo2023.cpp 181

You are trying here to call ::SetInt32 on a const BaseContainer. This cannot work, as your container is immutable and SetInt32 is not a const member function. You must retrieve the mutable container. Note that this is not always possible now. When you get passed in a const BaseList2D* you cannot access its writeable data container. When the node is const, you can only call const methods on the node, and all methods which return writeable data are non-const in 2024. You can cast away the const-ness of things if you really want to, but you risk crashing with that because things are const so that they can be accessed in parallel. The migration guide has a whole section on what to do in such cases.

In case you are a bit fuzzy on the concept of const-correctness in general or const-member functions in particular, these resources might help:

Iso Cpp - Const Correctness: The official explanation for the concept of const correctness. As common for the C++ Foundation, the official explanation is a bit convoluted and overly complicated (at least for my taste).
MSVC - const: Microsofts take on this is much user friendly, especially the section on const member functions/methods is much better IMHO.

NodeData Signature Changes

E.g.:

Error C4264 'Bool NodeData::Init(GeListNode *,Bool)': no override available for virtual member function from base 'NodeData'; function is hidden solo2023 ...\SoloPrefs.cpp 145

or:

Error C4263 'Bool SoloPrefs::GetDParameter(GeListNode *,const DescID &,GeData &,DESCFLAGS_GET &)': member function does not override any base class virtual member function solo2023 ...\SoloPrefs.cpp 134

Many NodeData methods and methods of NodeData derived interfaces have changed their signature. NodeData::Init has for example now a second argument Bool isCloneInit and NodeData::GetDParameter is now a const method and the first argument node is now also const; this is an example where you could not retrieve a writeable data container for node anymore since you are not supposed to write to the node in this method since it is now a cost method.

Cheers,
Ferdinand

Yakuza

@ferdinand
Thank you very much. I don't get a lot of that but was able to change the flow/logic of the plugin so that the compiler doesn't throw any errors anymore (but a bazillion warnings ). I have no idea if this will work because I still cannot test it since actually it's two plugins, the command plugin and its preferences dialog. The latter is unfortunately larger than the command itself and still throws 21 errors.

They all occur in PrefsDialogObject class. Do you have any ideas on these?

Severity	Code	Description	Project	File	Line	Suppression State
Error	C4263	'Bool SoloPrefs::Init(GeListNode *)': member function does not override any base class virtual member function	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	134	
Error	C4264	'Bool NodeData::Init(GeListNode *,Bool)': no override available for virtual member function from base 'NodeData'; function is hidden	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	146	
Error	C4263	'Bool SoloPrefs::GetDParameter(GeListNode *,const DescID &,GeData &,DESCFLAGS_GET &)': member function does not override any base class virtual member function	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	135	
Error	C4264	'Bool NodeData::GetDParameter(const GeListNode *,const DescID &,GeData &,DESCFLAGS_GET &) const': no override available for virtual member function from base 'NodeData'; function is hidden	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	146	
Error	C4263	'Bool SoloPrefs::GetDEnabling(GeListNode *,const DescID &,const GeData &,DESCFLAGS_ENABLE,const BaseContainer *)': member function does not override any base class virtual member function	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	137	
Error	C4264	'Bool NodeData::GetDEnabling(const GeListNode *,const DescID &,const GeData &,DESCFLAGS_ENABLE,const BaseContainer *) const': no override available for virtual member function from base 'NodeData'; function is hidden	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	146	
Error	C4263	'Bool SoloPrefs::GetDDescription(GeListNode *,Description *,DESCFLAGS_DESC &)': member function does not override any base class virtual member function	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	138	
Error	C4264	'Bool NodeData::GetDDescription(const GeListNode *,Description *,DESCFLAGS_DESC &) const': no override available for virtual member function from base 'NodeData'; function is hidden	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	146	
Error	C2664	'Bool SoloPrefs::InitValues(const DescID &,Description *)': cannot convert argument 1 from '<unnamed-enum-PREF_SOLOPREFS_MAIN_GROUP>' to 'const DescID &'	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	210	
Error	C2440	'<function-style-cast>': cannot convert from 'initializer list' to 'GeData'	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	230	
Error	C2664	'Bool SoloPrefs::InitValues(const DescID &,Description *)': cannot convert argument 1 from '<unnamed-enum-PREF_SOLOPREFS_MAIN_GROUP>' to 'const DescID &'	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	272	
Error	C2440	'return': cannot convert from 'const BaseContainer *' to 'BaseContainer *'	solo2023	D:\MAXON_CODE\C4D_2024_2_CODE\sdk\plugins\solo2023\source\SoloPrefs.cpp	287

ferdinand

Hey @Yakuza,

these are the exact same errors I explained above.

// 2023 and earlier NodeData::Init
Bool SoloPrefs::Init(GeListNode* node)
// 2024 and later NodeData::Init
Bool SoloPrefs::Init(GeListNode* node, Bool isCloneInit)

// 2023 and earlier NodeData::GetDParameter
Bool SoloPrefs::GetDParameter(GeListNode* node, const DescID& id, GeData& t_data, DESCFLAGS_GET& flags)
// 2024 and later NodeData::GetDParameter
Bool SoloPrefs::GetDParameter(const GeListNode *node, const DescID &id, GeData &t_data, DESCFLAGS_GET &flags) const

When you then try to declare a virtual function on your SoloPrefs, the compiler complains because you are trying to declare a function which does not exist anymore on the base class (PrefsDialogObject I assume) you are overriding.

Cheers,
Ferdinand

Yakuza

Oh sorry, thank you. I totally missed that.