Prefer compile-time checking to run-time checking

Reason

Code clarity and performance. You don't need to write error handlers for errors caught at compile time.

Example

// Int is an alias used for integers
int bits = 0;         // don't: avoidable code
for (Int i = 1; i; i <<= 1)
    ++bits;
if (bits < 32)
    cerr << "Int too small\n";

This example fails to achieve what it is trying to achieve (because overflow is undefined) and should be replaced with a simple static_assert:

// Int is an alias used for integers
static_assert(sizeof(Int) >= 4);    // do: compile-time check

Or better still just use the type system and replace Int with int32_t.

Example

void read(int* p, int n);   // read max n integers into *p

int a[100];
read(a, 1000);    // bad, off the end

better

void read(span<int> r); // read into the range of integers r

int a[100];
read(a);        // better: let the compiler figure out the number of elements

Alternative formulation: Don't postpone to run time what can be done well at compile time.

Enforcement

• Look for pointer arguments.
• Look for run-time checks for range violations.