Why you should care
It is needlessly complex to invert the result of a boolean comparison. The opposite comparison should be made instead. This is furthermore the case in compound conditions.
How we detect
CAST Highlight counts one occurrence each time a conditions begins with an unjustified negation.
The negation is justified if it provides more benefits than disadvantages.
To evaluate the needing of using a negation, check how many “!” operators appear or disappear if we take the opposite conditional expression. Count one violation if the resulting number of ‘!’ is less or equal than is the original expression.
Consider conditions expressions that comply with the following patterns :
The negation is justified if it provides more benefits than disadvantages.
To evaluate the needing of using a negation, check how many “!” operators appear or disappear if we take the opposite conditional expression. Count one violation if the resulting number of ‘!’ is less or equal than is the original expression.
Consider conditions expressions that comply with the following patterns :
- if (!( ….. ))
- while (!( ….. ))
- return !( … )
- … = !( … )
fun toto () {
if (!(a == 2)) { b++ } // Not compliant, prefer (a != 2)
val b = !(i < 10) // Not compliant, prefer (i >= 10)
if (!((a>b) && titi() || !(a==1) && b==6)) { b++ }
// not compliant, prefer (((a<b) || !titi()) && ((a==1) || b!==6))
return !(!entityOptions.containerType.isFragment || !(entityOptions.cache ?: getGlobalCacheImpl(currentClass)).hasCache)
// not compliant, prefer (entityOptions.containerType.isFragment && (entityOptions.cache ?: getGlobalCacheImpl(currentClass)).hasCache)
a = !(b && c && d) // OK, because (!b || !c || !d) is not more readable.
if (!(a is FunctionDescriptor || a is PropertyDescriptor || a is PackageFragmentDescriptor)) {return}
// not compliant, prefer (a !is FunctionDescriptor && a !is PropertyDescriptor && a !is PackageFragmentDescriptor)
}
References
About CAST and Highlight’s Code Insights
Over the last 25 years, CAST has leveraged unique knowledge on software quality measurement by analyzing thousands of applications and billions of lines of code. Based on this experience and community standards on programming best practices, Highlight implements hundreds of code insights across 15+ technologies to calculate health factors of a software.