Question

I’m getting a signature mismatch with a method I’m exposing to python. Here’s the code below

class StatusEffect
{
public:
   //Virtual functions and non related ommitted
   void AddCancellation(std::string &effect)
   {
       CancelsEffects.insert(effect);
   }
}

There are some virtual methods in StatusEffect that I want to override in my python scripts, so I created an class wrapper. The wrapper does not override or change AddCancellation in any way, I’m simple showing it to mark

struct StatusEffectWrapper : Game::StatusEffects::StatusEffect
{
   //Wrappings for virtual functions here. I don't touch AddCancellation
}

I expose it to python as follows:

 class_<StatusEffects::StatusEffect, boost::noncopyable, std::auto_ptr<StatusEffectWrapper> >("StatusEffect")
    .def("AddCancellation", &StatusEffect::AddCancellation)
    ;

In my python file, I extend the basic StatusEffect class like so:

class StatCreepEffect(StatusEffect):
    def __init__(self, name, stat_, rate_, descript, uid, turns, prior, canrefresh, poseffect, cats, conds, flgs, sep, pers, cancels):
        StatusEffect.__init__(self, name, descript, uid, turns, prior, canrefresh, poseffect, cats, conds, flgs, sep, pers)
        self.rate = rate_
        self.stat = stat_
        self.PushCancellations(cancels)
    def PushCancellations(self, cancels):
        for cancel in cancels:
            print (cancel)
            self.AddCancellation(cancel)

Regen = StatCreepEffect("Regen", Stat.HP, 0.05, "Regenerates a small amount of HP every turn", PrimaryEngine.GetUID(), 14, 4, True, True, StatusCategories.SC_Regen, 0, StatusFlags.TickEffect, True, StatusPersistence.SP_Timer_Cure, ["Poison", "Poison-"])

However, when I do so, I get the following error:

Poison
Traceback (most recent call last):
  File "..\..\..\Resources\Scripts\StatusEffects.py", line 27, in <module>
    Regen = StatCreepEffect("Regen", Stat.HP, 0.05, "Regenerates a small amount
of HP every turn", PrimaryEngine.GetUID(), 14, 4, True, True, StatusCategories.S
C_Regen, 0, StatusFlags.TickEffect, True, StatusPersistence.SP_Timer_Cure, ["Poi
son", "Poison-"])
  File "..\..\..\Resources\Scripts\StatusEffects.py", line 11, in __init__
    self.PushCancellations(cancels)
  File "..\..\..\Resources\Scripts\StatusEffects.py", line 23, in PushCancellati
ons
    self.AddCancellation(cancel)
Boost.Python.ArgumentError: Python argument types in
    StatusEffect.AddCancellation(StatCreepEffect, str)
did not match C++ signature:
    AddCancellation(class Game::StatusEffects::StatusEffect {lvalue}, class std:
:basic_string<char,struct std::char_traits<char>,class std::allocator<char> > {l
value})

I’m not entirely sure what the problem is. StatCreepEffect should be an instance of StatusEffect shouldn’t it? And Boost::python automatically handles the conversion of string doesn’t it? Am I calling the method incorrectly? It feelslike it’s something small that I’ve missed, but I’m not sure what it is. Any help would be appreciated.

Answer 1

Turns out I need to have

void AddCancellation(std::string &effect)
{
   CancelsEffects.insert(effect);
}

as

void AddCancellation(const std::string &effect)
{
   CancelsEffects.insert(effect);
}