Only want to say

[Jacob Carlborg]

On Monday, 11 January 2021 at 22:12:15 UTC, ddcovery wrote:

> It's true.  I suppose you mainly refer to assertions over 
> shared (not exclusive) resources: you can't "snapshot" a 
> pre/post state and demonstrate that your function is the 
> responsible of this transformation.
>
> But the think here is I'm running a set of batch commands (not 
> only 7z) over folders/files assuming that no other one is 
> interested in.
>
> It is a really relaxed scenery, but enough for the tasks.

`assert` should be used to verify logical assumptions in your 
program. To verify things in the environment, exceptions should 
be used. You can drop the `in` and `out` contracts and use the 
`enforce` function the same way as `assert` is used. It will 
throw an exception if the condition doesn't hold.

Exceptions inheriting from the class `Exception` should be thrown 
when there's an error related to the environment. I.e. a missing 
file, failed to connect to a server and so on.

Exceptions inheriting from the class `Error` should be thrown 
when there's a logical error in the program, this is what 
`assert` does. This includes accessing an array outside of its 
bounds, failing to handle all cases in a `final switch` statement 
and so on.

`assert` and contracts can be removed from the code, depending on 
which compiler flags are being used. Exceptions will always stay.

In your case, there can be something like anti-virus software 
which is running in the background and decides to remove your 
files which the program is processing.

--
/Jacob Carlborg