Part of the software developer job is to find new and better ways to solve problems. Writing code using his/her wits, intelligent and creativity. However, sometimes being too clever can lead to hard to track bugs, maintainability issues and impossible to understand code. Is all cleverly written code good code, or is it a problem just waiting to happen? In this session, I will show you real world examples of cleverly written code. And show you how we can use clean code principles, refactoring and design patterns, to transform that code from clever code to good code, code one that your peers - and future self - would thank you for writing.

1. From Clever code
to Better code
Dror Helper | http://helpercode.com | Practical Software | @dhelper

2. Consultant & software architect @ Practical Software
Developing software since 2002
Clean Coder & Test Driven Developer
Pluralsight author
B: http://helpercode.com
T: @dhelper
About.ME

3. A long time ago,
in an office not that far from here . . . .

4. #define GET_VAL( val, type )
{
ASSERT( ( pIP + sizeof(type) ) <= pMethodEnd );
val = ( *((type *&)(pIP))++ );
}

5. What this code does now I understand, clever it is!

6. Why do we write Clever Code?
Because we can
Because we have to
We don’t know any better
Performance

7. void send(short* from, short* to, size_t count) {
int n = (count + 7) / 8;
switch (count % 8) {
case 0: do { *to = *from++;
case 7: *to = *from++;
case 6: *to = *from++;
case 5: *to = *from++;
case 4: *to = *from++;
case 3: *to = *from++;
case 2: *to = *from++;
case 1: *to = *from++;
} while (--n > 0);
}
}
12
n = 2
<-- 4
--->
--->
--->
--->
N = 1
--->
--->
--->
--->

8. REALITY CHECK:
We write Clever Code because it makes us feel good
* Most programmers love to be clever

9. There is more than
one way to write
Clever Code

10. public void int GetNextSize(int i)
{
return i > 0 ? i << 2 : ~(i << 2) + 1;
}
public void int GetNextSize(int i)
{
return Math.Abs(i * 4);
}

11. if((i & (i - 1) == 0)
{
...
}
if(IsPowerOfTwo(i))
{
...
}
public bool IsPowerOfTwo(int i)
{
return ((i & (i - 1) == 0;
}

12. Low level programming
Avoid when you can
Refactor to show intent

13. Compressed Code
a = y[0]>y[1] ? (b=1,0) : (b=0,1);
if(y[0] > y[1])
{
a = 0;
b = 1;
} else {
a = 1;
b = 0;
}

15. do{
// code goes here
if(some condition)
break;
// ...
if(other condition)
break;
// ...
} while(false)
// cleanup here

16. public class Tree<T> {
public T Value { get; }
public Tree<T> Left { get; }
public Tree<T> Right { get; }
public void Find(T value)
{
if(Value.Equals(value))
throw new FoundElementException<T>(this);
Left?.Find(value);
Right?.Find(value);
}
}

17. Creative (ab)use
Don’t surprise the reader!
Think of a better way to express yourself

18. Writing < Reading < Debugging

19. What about performance?

20. Optimizations
void calculate(struct salesinfo* sales)
{
jmp_buf buffer;
int i=setjmp(buffer);
if (!(i<sales->count))
RETURN_NOTHING;
addToSubtotal(sales->values[i]);
if (i<sales->count)
{
longjmp(buffer,i+1);
}
}
void calculate(struct salesinfo*sales)
{
for(int i = 0; i < sales->count; i++)
{
addToSubtotal(sales->values[i]);
}
}

21. Real optimizations
float InvSqrt(float x)
{
float xhalf = 0.5f * x;
int i = *(int*)&x;
i = 0x5f375a86 - (i >> 1);
x = *(float*)&i;
x = x * (1.5f - xhalf * x * x);
return x;
}

22. Is clever code
Good or Evil?

23. Is clever code
Good or Evil?

24. #define GET_VAL( val, type )
{
ASSERT( ( pIP + sizeof(type) ) <= pMethodEnd );
val = ( *((type *&)(pIP))++ );
}
void parseCode(BYTE* pIp, BYTE* pMethodEnd)
{
int valueType = getValueType(pIp)
while(pIp < pMethodEnd)
{
switch(valueType){
case ValueType::INT:
int value;
GET_VAL(value, int)
// do something with value
break;
case ValueType::BYTE:
...
}
}
}

25. Thank you 
Dror Helper | http://helpercode.com | @dhelper

26. Links
• https://stackoverflow.com/questions/178265/what-is-the-most-hard-to-understand-
piece-of-c-code-you-know
• https://www.simplethread.com/dont-be-clever/
• https://stackoverflow.com/questions/2338612/confusing-use-of-a-comma-in-
an-if-statement
• http://thedailywtf.com/articles/Longjmp--FOR-SPEED!!!
• http://www.lomont.org/Math/Papers/2003/InvSqrt.pdf