D 2018-07-05T18:32:10.705
L depends
N text/x-markdown
P 4b12ddaf6a222cc458e53b74ba92492b2db9ce350043fe3c3d5669b2abf1abf4
U mario
W 2343
## # depends:
Lists other plugins or language/system libraries which the current plugin expects:
# depends: corefuncs, json_io, bin:bash
Each entry is a plugin [basename](wiki/internal-fields#id), and indicates it must be available/active alongside.
* The recommended field name is "depends" and not "require" - for parity with the Debian packaging spec, and because it sounds less stringent.
* Not every application would want to enforce this *strictly*. Because dynamic languages can soft-detect dependencies usually.
* Within a plugin management UI, the depends: list could be used for installation warnings.
It's optional, and might be treated as documentation in some implementations.
### Versioned dependencies
Additionally the plugin names can be suffixed with a version comparison:
# depends: core (>= 2.0.0)
Which obviously does require the plugin manager to be somewhat more involved. You'll often get away just implementing a `>=` check. Other version expressions are usually overkill for simple application-level features.
### System/language references
While a `TYPE:name` entry can reference other scopes (instead of application-local plugins)
| `bin:imagemagick` | verify a binary exists |
| `python:lxml` | for language modules |
| `sys:amd64` | e.g. the architecture. |
| `deb:anacron` | as hint for the system package manager. |
| `api:archnemesis` | see [api](wiki/api) |
This is quite informal still. There's seldomly practical value to implement such complex dependency lookups, or these exact ones. This is just the advised syntax.
### Magic basenames
Optionally one could handle a few plain basenames specically For instance checking the current language runtime with:
# depends: python (>= 3.4)
Or, if feasible, even module versions
# depends: php:sqlite (>= 3.24)
### Related fields
Depending on complexity other fields might be used alongside:
#### # conflicts:
Does occasionally make sense for variants or mutally exclusive features.
#### # provides:
Defines a virtual feature identifier to be present. Less commonly needed for application plugins.
#### # suggests:
A weak recommendation of other plugins to go along with. Should foremost be handled in the admin UI or a plugin download interface.
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