Why is this an issue?
Nested control flow statements if, for, do, while, switch and try are
often key ingredients in creating what’s known as "Spaghetti code". This code smell can make your program difficult to understand and maintain.
When numerous control structures are placed inside one another, the code becomes a tangled, complex web. This significantly reduces the code’s
readability and maintainability, and it also complicates the testing process.
Exceptions
Each use of a macro containing control flow statements is counted as one nesting level, even if the macro contains more than one control flow
statement.
#define FOREACH(V,ARR) if(ARR!=nullptr) for(int V=0; V<(sizeof(ARR)/sizeof(ARR[0])); V++)
if (condition1) { // Compliant; depth = 1
if (condition2) { // Compliant; depth = 2
FOREACH(i, arr) { // Compliant; depth = 3 (not 4)
if (condition3) { // Noncompliant; depth = 4
/* ... */
}
}
}
}
How to fix it
Code examples
The following example demonstrates the behavior of the rule with the default threshold of 3 levels of nesting and one of the potential ways to fix
the code smell by introducing guard clauses:
Noncompliant code example
if (condition1) { // Compliant - depth = 1
/* ... */
if (condition2) { // Compliant - depth = 2
/* ... */
for (int i = 0; i < 10; i++) { // Compliant - depth = 3
/* ... */
if (condition4) { // Noncompliant - depth = 4, which exceeds the limit
if (condition5) { // Depth = 5, exceeding the limit, but issues are only reported on depth = 4
/* ... */
}
return;
}
}
}
}
Compliant solution
if (!condition1) {
return;
}
/* ... */
if (!condition2) {
return;
}
for (int i = 0; i < 10; i++) {
/* ... */
if (condition4) {
if (condition5) {
/* ... */
}
return;
}
}
Resources
