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NextAction refactoring to eliminate sentinel arrays and pointers (#1923)

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# Description

This PR aims to refactor the NextAction declaration to achieve two
goals:

## Eliminate C-style sentinel arrays

Currently, a double pointer (`NextAction**`) approach is being used.
This an old pre-C++11 (< 2011) trick before `std::vector<>` became a
thing.
This approach is painful for developers because they constantly need to
declare their `NextAction` arrays as:
```cpp
NextAction::array(0, new NextAction("foo", 1.0f), nullptr)
```
Instead of:
```cpp
{ new NextAction("foo", 1.0f) }
```
The first argument of `NextAction::array` is actually a hack. It is used
to have a named argument so `va_args` can find the remaining arguments.
It is set to 0 everywhere but in fact does nothing. This is very
confusing to people unfamiliar with this antiquated syntax.
The last argument `nullptr` is what we call a sentinel. It's a `nullptr`
because `va_args` is looking for a `nullptr` to stop iterating. It's
also a hack and also leads to confusion.

## Eliminate unnecessary pointers for `NextAction`

Pointers can be used for several reasons, to cite a few:
- Indicate strong, absolute identity.
- Provide strong but transferable ownership (unlike references).
- When a null value is acceptable (`nullptr`).
- When copy is expensive.

`NextAction` meets none of these criteria:
- It has no identity because it is purely behavioural.
- It is never owned by anything as it is passed around and never fetched
from a registry.
- The only situations where it can be `nullptr` are errors that should
in fact throw an `std::invalid_argument` instead.
- They are extremely small objects that embark a single `std::string`
and a single `float`.

Pointers should be avoided when not strictly necessary because they can
quickly lead to undefined behaviour due to unhandled `nullptr`
situations. They also make the syntax heavier due to the necessity to
constantly check for `nullptr`. Finally, they aren't even good for
performance in that situation because shifting a pointer so many times
is likely more expensive than copying such a trivial object.

# End goal

The end goal is to declare `NextAction` arrays this way:
```cpp
{ NextAction("foo", 1.0f) }
```

> [!NOTE]
> Additional note: `NextAction` is nothing but a hacky proxy to an
`Action` constructor. This should eventually be reworked to use handles
instead of strings. This would make copying `NextAction` even cheaper
and remove the need for the extremely heavy stringly typed current
approach. Stringly typed entities are a known anti-pattern so we need to
move on from those.
This commit is contained in:
Nicolas Lebacq
2026-01-06 11:37:39 +00:00
committed by GitHub
parent b13fb7d12a
commit c9cc4324d3
197 changed files with 6795 additions and 4054 deletions
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28
src/TravelMgr.cpp
View File

@@ -3409,13 +3409,14 @@ void TravelMgr::LoadQuestTravelTable()
{
Strategy* strat = con->GetStrategy(stratName);
if (strat->getDefaultActions())
for (uint32 i = 0; i < NextAction::size(strat->getDefaultActions()); i++)
{
NextAction* nextAction = strat->getDefaultActions()[i];
const std::vector<NextAction> defaultActions = strat->getDefaultActions();
if (defaultActions.size() > 0)
{
for (NextAction nextAction : defaultActions)
{
std::ostringstream aout;
aout << nextAction->getRelevance() << "," << nextAction->getName()
aout << nextAction.getRelevance() << "," << nextAction.getName()
<< ",,S:" << stratName;
if (actions.find(aout.str().c_str()) != actions.end())
@@ -3427,27 +3428,24 @@ void TravelMgr::LoadQuestTravelTable()
actions.insert_or_assign(aout.str().c_str(), classSpecLevel);
}
}
std::vector<TriggerNode*> triggers;
strat->InitTriggers(triggers);
for (auto& triggerNode : triggers)
{
// out << " TN:" << triggerNode->getName();
for (TriggerNode*& triggerNode : triggers)
{
if (Trigger* trigger = con->GetTrigger(triggerNode->getName()))
{
triggerNode->setTrigger(trigger);
NextAction** nextActions = triggerNode->getHandlers();
std::vector<NextAction> nextActions = triggerNode->getHandlers();
for (uint32 i = 0; i < NextAction::size(nextActions); i++)
// for (uint32_t i = 0; i < nextActions.size(); ++i)
for (NextAction nextAction : nextActions)
{
NextAction* nextAction = nextActions[i];
// out << " A:" << nextAction->getName() << "(" <<
// nextAction->getRelevance() << ")";
std::ostringstream aout;
aout << nextAction->getRelevance() << "," << nextAction->getName()
aout << nextAction.getRelevance() << "," << nextAction.getName()
<< "," << triggerNode->getName() << "," << stratName;
if (actions.find(aout.str().c_str()) != actions.end())