Scripting: Do's and Don'ts – Arma Reforger

From Bohemia Interactive Community
Revision as of 12:00, 9 May 2022 by biki>Lou Montana (Fix link)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search
Don't Do
class ExampleClass {
  int LProcLgh;

	int stringlength( string Value ){
		LProcLgh= Value.Length();
		Print ( "String length obtained: "+LProcLgh );
		return LProcLgh;
	}
}
class ExampleClass
{
	protected int m_iLastProcessedLength;
 
	int GetStringLength(string value)
	{
		m_iLastProcessedLength = value.Length();
		Print("String length obtained: " + m_iLastProcessedLength);
		return m_iLastProcessedLength;
	}
 
	int GetLastProcessedLength()
	{
		return m_iLastProcessedLength;
	}
}

Keep variables as close as possible to their usage:

Don't Do
class ExampleClass
{
	protected int m_iLength;
 
	int GetStringLength(string name)
	{
		m_iLength = name.Length();
		Print("String length obtained: " + m_iLength);
		return m_iLength;
	}
}
class ExampleClass
{
	// keeping the variable into method scope and away from the instance
 
	int GetStringLength(string name)
	{
		int length = name.Length();
		Print("String length obtained: " + length);
		return length;
	}
}

Keep a strong reference (ref keyword) to required objects:

Don't Do
// this array only lists pointers but does not increase the reference count
array<ExampleClass> classArray = new array<ExampleClass>();
 
for (int i = 0; i < 10; i++)
{
	ExampleClass newInstance = new ExampleClass();
	classArray.Insert(newInstance);
	// newInstance will be deleted at the end of the scope
	// as there are no references to it
}
// this array keeps strong references to its items
array<ref ExampleClass> classArray = new array<ref ExampleClass>();
 
for (int i = 0; i < 10; i++)
{
	ExampleClass newInstance = new ExampleClass();
	classArray.Insert(newInstance);
	// classArray keeps a strong reference to newInstance - it will not be cleared
}

Avoid strong reference cyclic trap:

Don't Do
Here, both ParentClass and ChildClass have a strong reference to each other, keeping the reference count above zero - creating an "island of isolation" (see Automatic Reference Counting for more information).
class MainClass
{
	ref SubClass m_subClass;
 
	void MainClass()
	{
		m_subClass = new SubClass(this);
	}
}
 
class SubClass
{
	ref MainClass m_parent;
 
	void SubClass(MainClass parent)
	{
		m_parent = parent;
	}
 
	void DoSomething()
	{
		Print(m_parent);
	}
}
Here, the MainClass needs the SubClass (it creates it in its constructor meaning it needs it to work) but the subClass does not require MainClass - if the MainClass reference doesn't exist, it will simply not use it.
class MainClass
{
	ref SubClass m_subClass;
 
	void MainClass()
	{
		m_subClass = new SubClass(this);
	}
}
 
class SubClass
{
	MainClass m_parent; // ref removed
 
	void SubClass(MainClass parent)
	{
		m_parent = parent;
	}
 
	void DoSomething()
	{
		if (!m_parent) // null safety check
		{
			return;
		}
		Print(m_parent);
	}
}