Practices - Argument Passing

The following rules apply to argument passing.

1. When passing an argument of a non POD type that will not change in the function, use const references ( const & )

2. When passing an argument that may change use normal reference

3. Objects of classes with difficult to follow lifecycle or complicated / costly copy semantics shall be passed by boost::intrusive_ptr

If none of these rules apply, or additional constraints make them not feasible, then follow the paradigm:

• Safety of operation first

• Clarity of intent second

• Speed last

If a need arises to use raw pointers as arguments then the following rules apply:

const &, const * - ownership stays in the calling code

&, * - ownership stays in the calling code, value may be freely changed

** - ownership is transferred to callee, calling code has to explicitly zero the variables which held the code or overwrite the variable

some_class function1(
		arg const & _first
	,	arg2 * _second
	,	arg3 ** _third
	);

It is assumed that _first is immutable, _second may be changed by the function1 and management of _third is up to the function1.

These rules may be changed when dealing with an interface from an external library