dir/extract: add mode for overwriting existing files

[tmplt]

A dir::ExtractMode enum is added with the options Overwrite and FailIfExists. The latter is the current behavior. The former truncates any already existing files.

[Michael-F-Bryan]

If people do want their files to be overwritten, can't they just call std::fs::remove_dir_all() first?

[tmplt]

Michael Bryan ***@***.***> writes:

If people do want their files to be overwritten, can't they just call std::fs::remove_dir_all() first?

Yes, but this will remove all files in the directory. Overwriting files allow "untracked" files to remain.

[tmplt]

Will this be merged if conflicts are fixed?

[Michael-F-Bryan]

I'm going to close this PR for now.

My thinking is that:

• The Dir::extract() method is a convenience function which will work for 90% of use cases
• The implementation is a trivial recursive function that you can write yourself
• Adding extra arguments and types means now everyone will need to be choose how naming collisions are handled and add an extra use include_dir::ExtractMode, even though they aren't concerned about this use case
• If people want to customise the extraction process they should be able to implement their own.

See also Project Goals and Values.