I am not C expert, so be polity. I do not see something similar in C world,
but similar techniques in other languages, such like Vala.
I suggest to create two new pointer type:
1. can-be-null
2. cannot-be-null
(You must find other words to describe it behavior).
First enforces to compiler checking it is not null, when it was used (by ->
operator) or used, when cannot-be-null is excepted. Of course, user can cast
to cannot-be-null to avoid checking. So:
1. Usage with -> operator, or * must be placed inside conditional block, with
contains null check in condition
2. Passing as cannot-be-null (except explicit conversion) will requires to put
in block as above
The same restrictions apply to put normal pointer in case, when cannot-be-null
excepted.
Additionally, break-instruction word will be reserved for functions, so exit
will be traded as end of control-flow and further code will be traded as
checked.
Imagine assert will be traded as break-ins
This code:
int get_vector_size(struct vector cannot-be-null *vec)
{
assert(vec != NULL)
return vec->size;
}
Will be correct, because assert macro will (possible) be extended to:
if (!(vec != NULL)) {
puts("assertion error: vec != NULL");
exit(1);
}
And exit will be break-instruction.
We could use cannot-be-null in some cases, such like:
int year;
scanf("How old are you:%d", &year);
But user could pass NULL as second parameter.
When pointers in scanf parameters are cannot-be-null, the compiler will
disallow pass null by us.
Of course - inside scanf must check if each parameter are not NULL.
Another code:
void error(const char *message)
{
perror(message);
}
And perror will have cannot-be-null word describe one's parameter.
This will cause compile-time-error, because message was passed to function,
which parameter is cannot-be-null.
Programmer should do:
void error(const char *message)
{
if (NULL != message)
perror(message);
}
What do you think. This will solve a lot of problems,
It could be also great to introduce function checking if any of it parameter
are null, but I do not known how to make it good-quality (simple in usage).
Programer should propably pass number of passed parameters, or type of
parameter before each.
