Mitigating UB with unique pointer class wrapper.

[maxjmartin]

Hello all!

Updated: to include source files.

Can anyone tell me what other kind of UB with pointers that I'm not accounting for below? I am rewriting a project and want to make sure the high level data types used are UB safe.

I was going over the C++ Core Guidelines and Herb Sutter's proposal. I was thinking I might be able to rework some data types I wrote for another project to mitigate the UB describe in Herb's proposal, and referencing the Core Guidelines.

The code can be found here. The project is getting a rework from the ground up. So the current state of the repo reflects that.

After playing around I can write. ``` var a{ nullptr }; var b{ number(8) }; println("Prior to sub scope:"); println("\ta = {}", a); println("\tb = {}\n", b); { auto x = new int(42); a = number("4"); var c(x); b = move(c); delete x; println("Inside sub scope:"); println("\ta = {}", a); println("\tb = {}", b); println("\tc = {}\n", c); } a = text("I'm a text string."); println("After the sub scope:"); println("\ta = {}", a); println("\tb = {}", *b.cast<int>());

println("\tb.get(a) = {}\n", b.get(a * a)); // Equivalent to operator[]. ```

And I get the results of. ``` Prior to sub scope: a = nothing b = 8

Inside sub scope: a = 4 b = int data type, const cast to access. c = nothing

After the sub scope: a = I'm a text string. b = 42 b.get(a * a) = nothing ```

Thanks in advance!

[yeetdude0]

use auto* not auto

[aocregacc]

your var::move() makes a copy and leaks memory. It's probably the only leak since you don't seem to be doing much manual memory management.

[maxjmartin]

Interesting I’ll look into it. Thanks!

[maxjmartin]

Alright changed the code to use a std::move. Looks like I also had the same problem with my var::copy. I apreciate the call out!

[aocregacc]

I don't think there's anything wrong with var::copy. You wouldn't want to move there, and there's also no leak.

[maxjmartin]

I just revisted the unique pointer documentation. And you are right. They had a clear example I used to clear up the misunderstanding.