Why can't I call a plugin method from a actor?

Development Programming & Scripting C++
,
1

Hi!
I was messing with plugins, and I can’t understand what’s the problem I’m facing:
First I created a plugin from the “editor stand alone window” preset and added the following code to the MyPlugin.h :

public:
	void UpdateMyTextBlock(FString MyNewContent);

	static inline FMyPluginModule& Get() { return FModuleManager::LoadModuleChecked <FMyPluginModule>("MyPlugin"); };

private:
	TSharedPtr<STextBlock> MyTextBlock;

and implemented UpdateMyTextBlock on my cpp file, and altered the SNew(STextBlock) to SAssingNew, like this:

TSharedRef<SDockTab> FMyPluginModule::OnSpawnPluginTab(const FSpawnTabArgs& SpawnTabArgs)
{
	FText WidgetText = FText::FromString("OldText");

	return SNew(SDockTab)
		.TabRole(ETabRole::NomadTab)
		[
			// Put your tab content here!
			SNew(SBox)
			.HAlign(HAlign_Center)
			.VAlign(VAlign_Center)
			[
				SAssignNew(MyTextBlock, STextBlock)
				.Text(WidgetText)
			]
		];
}

void FMyPluginModule::UpdateMyTextBlock(FString MyNewContent)
{
	MyTextBlock->SetText(FText::FromString(MyNewContent));
}

And on my actor class I added the following:

MyActor.h:

private:
	FVector MyPosition;

MyActor.cpp:

#include "MyPlugin.h"

void AMyActor::Tick(float DeltaTime)
{
	Super::Tick(DeltaTime);

	if (MyPosition != GetTransform().GetLocation())
	{
		MyPosition = GetTransform().GetLocation();
		FString NewPosition = "X=" + FString::SanitizeFloat(MyPosition.X) + ", Y=" + FString::SanitizeFloat(MyPosition.Y) + ", Z=" + FString::SanitizeFloat(MyPosition.Z);
		FMyPluginModule::Get().UpdateMyTextBlock(NewPosition);
	}

}

Like this I get a link error. I tried adding the plugin module to the project dependencies, changing the slate private dependencies to public on the MyPlugin.Build.cs.
The only way I got this to work was to enable the slate dependencies on my project build.cs and moving the definition of UpdateMyTextBlock to the MyPlugin.h file.

I guess I can make a interface class to store actor calls and probe it with the plugin to make updates. But i wanted to understand why I can’t make it work in the original way.

Thanks in advance for any help or clues!

2

I’ve had similar problems in the past. The solution for me was to use the MYMODULE_API macro. These macros seem to mark certain classes (and I believe functions aswell) for DLL export.

In your case, you may need something like:

class MYPLUGIN_API FMyPluginModule : public IModuleInterface
{
...
public:
	void UpdateMyTextBlock(FString MyNewContent);

	static inline FMyPluginModule& Get() { return FModuleManager::LoadModuleChecked <FMyPluginModule>("MyPlugin"); };

private:
	TSharedPtr<STextBlock> MyTextBlock;
...
}

Here is the very limited documentation on these macros Module API Specifiers

Here is an Unreal Answers forum thread discussing them: What does the macro ProjectName_API do?

Hope this helps!

3 Likes
3

It really helped!
And it worked!

These are actually very usefull specifiers, very nice to know.

Thank you very much :smiley:

1 Like