Arma 3 Scripting

Code Positivity

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This page provides some insights into what it means to try and write code in a positive way, with the least negation as possible.

Overview

Code negation is (usually) using not (in SQF/SQS) or ! (in both SQF/SQS and Enforce Script); all in all, it is about searching for the opposite of what one wants. Examples:

SQF Enforce Script 
if (not alive player) then
{
    hint "you are dead";
}
else
{
    hint "you are alive";
};
 
if (value < minValue)
{
    Print("Value is invalid");
}
else
{
    Print("Value is valid");
}

Research (ref: https://www.researchgate.net/publication/10733819_Effects_of_Negation_and_Situational_Presence_on_the_Accessibility_of_Text_Information) has (ref: https://www.researchgate.net/publication/221438570_Some_Issues_on_Detecting_Negation_from_Text) shown (ref: https://medium.com/@Cuadraman/why-to-stop-writting-negavite-code-af5ffb17195) that negation in general (not just in code but also in reading, teaching etc) makes processing sentences more difficult for the human brain, making its message less impactful (although not in all cases (ref: https://www.psychologicalscience.org/news/releases/true-or-false-how-our-brain-processes-negative-statements.html)).

Examples

Do Don't 
// this is called Early Return / Bouncer pattern
if (isNull _control1) exitWith {};
if (isNull _control2) exitWith {};
if (isNull _control3) exitWith {};
// do something
 
if (not isNull _control1) then
{
    if (not isNull _control2) then
    {
        if (not isNull _control3) then
        {
            // finally do something
            // <- this is called Hadouken code style as per
            // the shape drawn by the brackets
        };
    };
};
 
// whenever possible without rewriting everything
// or doubling the methods, of course
if (unit.IsAlive() && unit.IsInjured())
    DoHealThing();

// alternatively
if (unit.IsDead())
    DoDeathThing();
else if (unit.IsPerfectHealth())
    DoPerfectThing();
else // injured
    DoHealThing();
 
// sometimes, only negative methods are available
if (!unit.IsPerfectHealth() && !unit.IsDead())
    DoHealThing();

Counter Examples

As most if not all rules of development, this rule is a rule of thumb that is not to be enforced at all cost.

Don't Do 
if (isNull _control) then
{
}
else
{
    systemChat "the control exists";
};
// or, even more convoluted and less performance-friendly
if (str _control find "NULL" == -1) then
{
    systemChat "the control exists";
};
 
if (not isNull _control) then // neater
{
    systemChat "the control exists";
};
 
if (m_aElements.Count() > 0)
    Print("There are elements!");
// note that in some cases, storing the count in a variable
// saves further calculations in below code
 
if (!m_aElements.IsEmpty())
    Print("There are elements!");

See Also