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Artifact ID: 34261983fe9a5e0d9dff56d37c9390573cc52ebe7241368348dd8d27ff230be9
Page Name:config
Date: 2018-07-04 14:22:11
Original User: mario
Mimetype:text/x-markdown
Parent: 0d005d1d57f5d6cd8db91a1fd2b4e38fa3658cc409e76d3ddb8b22fd11c4f41f (diff)
Next 7487fe0092ccfa7199ac408dca5d2fb9282422b19e32f800efa5a8985cf78f80
Content

# config: {…}

The config: field is a list of entries describing feature- and application-level settings.

# config:
#    { name: linky, type: bool, description: autolink urls }
#    { name: xy.title, type: str, value: "blog title" }
#    { name: perm, type: select, select: 3=USER|2=EX|1=SUP|0=KERN }

PMD is about uniform feature lookup. And plugin handling goes hand in hand with configuration management. However it requires a structured field to avoid bulky definitions, yet support enough variation.

Usually config: contains multiple indented lines, each being a JSOL-dictionary.

{

name: associates some variable/constant/expression to a setting.
type: A few common types may cover 90% of configuration needs.
bool would render as checkbox often.
str for plain textual content.
int verifies the value to be numeric.
select defining a predefined list of defaults.
select: With select: "aaa┃bbb┃ccc" being the alternatives attribute for combobox options.
description: holds some elaboration on the key name.
value: just sets a default

}

select: alternatives

The syntax for select: is

  • preferrably "alt|alt|alt"
  • or with optional title "1=title|2=alternative|3=…".
  • Though implementations may allow to use , comma and | dash.
  • Or : like = again.

Other fields and types

Other per-config attributes migh encompass

  • category: and class: for decoration or grouping.
  • Or arg: and param: for defining commandline args rather than global application settings.

Other types might be

  • text for lengthy textarea-style strings),
  • color for a color picker,
  • file bringing up a file selection dialog
  • Or table/csv/dict for supporting more complex (Excel-style) setting lists.

Storage and key name:

Notably this scheme just defines a list of available options. It does not prescribe if they're stored in an .ini, .json, xml or code file, or a database perhaps.
Applications might utilize different stores even, and dispatch depending on the name: syntax

  • For example name: ALL_UPPERCASE might become a code constant,
  • While name: sectioned.feature.option indicated an INI setting,
  • Or name: "$cfg.plugins[after][]" even a literal code target.

So names can be somewhat free-form. I'd avoid including the $ sigil however, or spaces obviously. Mostly-alphunumeric and dotted keys are certainly most versatile.

Regex tokenizer

You can get by with a somewhat simple regex extractor for this config scheme. It's simply finding {…} pairs, then splitting key-value pairs, and handling optional quoting.

  • Which allows syntax alternatives [:=>]+ for key-value pairs.

  • Same as shortened/aliased type names add some user-friendliness.

Of course a stringent JSON-parser could be used. But that's obstructing maintanability, and buys little performance-wise. (Plugin or option management is rarely done during runtime; but confined to some admin or installer UI.)

Purpose

Once config options are easily parseable, it quickly pays off to implement a centralized option/admin UI. And it sometimes can be combined with plugin configuration itself. Which is why plugin meta data defines this simple scheme.