A practical scenario for using include(), include_once() and require() constructs
php, require-once
Solution
IMHO there is no real scenario that fits `include` and `include_once` because of two reasons:
- It's highly unlikely that your intention is to include a file and at the same time you don't really care if it's included (e.g. if the file does not exist and execution continues).
- Even if that is the case, `include` will emit a warning which is bad style (zero-warning code is a good thing to strive for). You can prevent this most of the time with a check like `is_file`, but then you know that the file does exist so why not `require` it?
For `require` vs `require_once`: if a file can legitimately be parsed more than once (e.g. an HTML template) use the former. If it brings code inside your application (the vast majority of cases) use the latter.
Problem
Among `include`, `include_once`, `require` and `require_once` I always just use `require_once`. Many third-party frameworks just use `require_once` as well. Can anybody please describe a real scenario that another construct must be used?