How to avoid C++ anonymous objects

Question

I have a ScopedLock class which can help to release lock automatically when running out of scope. However, the problem is: Sometimes team members write invalid

Answer 1

I have seen an interesting trick in one codebase, but it only works if your scoped_lock type is not a template (std::scoped_lock is).

#define scoped_lock(x) static_assert(false, "you forgot the variable name")

If you use the class correctly, you have

scoped_lock lock(mutex);

and since the scoped_lock identifier isn't followed by an open paren, the macro won't trigger and the code will remain as it is. If you write\

scoped_lock(mutex);

the macro will trigger and the code will be substituted with

static_assert(false, "you forgot the variable name");

This will generate an informative message.

If you use a qualified name

threads::scoped_lock(mutext);

then the result will still not compile, but the message won't be as nice.

Of course, if your lock is a template, the bad code is

scoped_lock(mutex);

which won't trigger the macro.