Don’t overwrite default.nix if it’s not explicitely given as input

[Profpatsch]

It’s kind of in bad taste to overwrite existing files if the user has not explicitely specified they should be overwritten (that is by adding arguments with their name).

[kolloch]

It's the unix way! (at least partially kidding)

Anyways, I think it is quite common to overwrite an existing file in this case because you update your file. But for default.nix it is probably not such a great choice.

I could

• Follow your suggestion and require an overwrite flag.
• Look for a string like "Generated by crate2nix" and only overwrite if it is there.
• Change the default to Cargo.nix so that it is unlikely that it is used already for something else.

What do you think?

[Profpatsch]

I would just add a check if the user doesn’t specify anything explicitely; so:

crate2nix generate -o default.nix => overwrite file without a warning
crate2nix generate => if default.nix exists, abort with exists error, if not, just write to it.