Databases
StackOverflow2013
Postsdbo
POBoost Python - Losing Data across function call
 

Note that there are some explanatory texts on larger screens.

plurals
  1. POBoost Python - Losing Data across function call
    primarykey
    data
    text
    <p>I'm having a really weird issue in boost python. I'm focusing on a particular property/method to simplify the example. Here's the situation:</p> <p>In my program, I have a class called Attack. With the following layout (simplified for example)</p> <pre><code>class Attack : public Action { public: virtual int CalculateDamage(const std::vector&lt;BattleCharacter*&gt;&amp; users, BattleCharacter* target, const std::vector&lt;Actions::ActionTarget&gt;&amp; targets, BattleField *field); protected: bool Hit; } </code></pre> <p>I exposed Attack to python, making it overridable, as follows:</p> <pre><code>struct AttackWrapper : Game::Battles::Actions::Attack { int AttackWrapper::CalculateDamage(const std::vector&lt;Game::Battles::BattleCharacter*&gt;&amp; users, Game::Battles::BattleCharacter* target, const std::vector&lt;Actions::ActionTarget&gt;&amp; targets, Game::Battles::BattleField *field) { return call_method&lt;int&gt;(self, "CalculateDamage", users, ptr(target), targets, ptr(field)); } int AttackWrapper::CalculateDamageDefault(const std::vector&lt;Game::Battles::BattleCharacter*&gt;&amp; users, Game::Battles::BattleCharacter* target, const std::vector&lt;Actions::ActionTarget&gt;&amp; targets, Game::Battles::BattleField *field) { return this-&gt;Attack::CalculateDamage(users, target, Targets, field); } } </code></pre> <p>And the python exposing is done as follows:</p> <pre><code>class_&lt;Attack, AttackWrapper, boost::shared_ptr&lt;Attack&gt;, bases&lt;Action&gt; &gt;("Attack") .def("CalculateDamage", &amp;AttackWrapper::CalculateDamageDefault); </code></pre> <p>I initially thought everything was working fine, as I can override the <code>CalculateDamage</code> method within python and have it work correctly. However, When I want to use the normal <code>Attack-&gt;CalculateDamage</code>, the following happens:</p> <p>I only call <code>CalculateDamage</code> when Hit is true, and I can confirm via break point when I hit this line, Hit is true:</p> <pre><code>return call_method&lt;int&gt;(self, "CalculateDamage", users, ptr(target), targets, ptr(field)); </code></pre> <p>Now, because I haven't overriden <code>CalculateDamage</code> in Python for this attack instance, it ends up resolving to <code>AttackWrapper::CalculateDamageDefault</code>. But by the time I enter AttackWrapper::CalculateDamageDefault, Hit is no longer true. That is, when I break on this line:</p> <pre><code>return this-&gt;Attack::CalculateDamage(users, target, Targets, field); </code></pre> <p>Hit is false. So somewhere between </p> <pre><code>return call_method&lt;int&gt;(self, "CalculateDamage", users, ptr(target), targets, ptr(field)); </code></pre> <p>resolving to </p> <pre><code>return this-&gt;Attack::CalculateDamage(users, target, Targets, field); </code></pre> <p>my property's value is lost. I have no idea what could be causing this. Has anyone encountered something like this before? I think it may be being copied...</p>
    singulars
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PTQuestion
    1. USMegatron
    1. USMegatron
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. POBoost Python - Losing Data across function call
      1. This table or related slice is empty.
      1. VTUpMod
    1. COAdd explicit copy constructors/constructor/destructor, and check that your class isn't being passed around by value somewhere.
      singulars
      1. POBoost Python - Losing Data across function call
      1. USJames
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload