Ideas for with blocks for weak variables

gistfile1.m

// function
void with(id obj, void (^block)(id obj))
{
    block(obj);
}

// example use
with(blah, ^(Blah *blah) {
    // use blah here
});


// macro
#define with(var, ...) do { __typeof__(var) __tmp_ ## var = var; __typeof(__tmp_ ## var) var = __tmp_ ## var; __VA_ARGS__ } while(0)

// example use
with(blah, {
    // use blah here, it's strong
});


// multi-variable macro
#define with(...) do { \
    id __with_vars[] = { __VA_ARGS__ }; \
    void (^__with_block)(void) = __with_vars[sizeof(__with_vars)/sizeof(*__with_vars) - 1]; \
    __with_block(); \
    for(unsigned __with_i = 0; __with_i < sizeof(__with_vars)/sizeof(*__with_vars); i++) \
        [__with_vars[__with_i] self]; \
} while(0)

// example use
with(foo, bar, baz, ^{
    // use foo, bar, baz
});


// utterly awful multi-variable macro
#define IDARRAY(...) ((id[]){ __VA_ARGS__ })
#define IDCOUNT(...) (sizeof(IDARRAY(__VA_ARGS__)) / sizeof(id))

#define with(...) _with_helper(IDARRAY(__VA_ARGS__), IDCOUNT(__VA_ARGS__))

void _with_helper(id objs[], unsigned count)
{
    // this is really bad
    for(unsigned i = 0; i < count; i++)
        objc_autorelease(objc_retain(objs[i]));
}

// example use
with(foo, bar, baz);
// now use foo, bar, baz; if non-nil, will stay non-nil until next autorelease pool pop