Configuration

This library implements a UTF-8 text file scheme for configuration and user settings as follows:

  • Comments start with --
  • Leading, trailing, and extra whitespace is ignored
  • Each parameter is named and delimited as follows:
<parameter-name> = <parameter-value>

Parameter values may be:

  • Strings delimited with either single- or double-quotes
  • Tables delimited with {} that may contain strings, booleans, or numbers
  • Booleans (true or false)
  • Numbers

Currently the following are not supported:

  • Tables embedded within tables
  • Tables containing strings that contain commas

A sample configuration file might be:

-- Configuration File for "Hairpin and Dynamic Adjustments" script
--
left_dynamic_cushion         = 12        --evpus
right_dynamic_cushion        = -6        --evpus

Configuration Files

Configuration files provide a way for power users to modify script behavior without having to modify the script itself. Some users track their changes to their configuration files, so scripts should not create or modify them programmatically.

  • The user creates each configuration file in a subfolder called script_settings within the folder of the calling script.
  • Each script that has a configuration file defines its own configuration file name.
  • It is entirely appropriate over time for scripts to transition from configuration files to user settings, but this requires implementing a user interface to modify the user settings from within the script. (See below.)

User Settings Files

User settings are written by the scripts themselves and reside in the user’s preferences folder in an appropriately-named location for the operating system. (The naming convention is a detail that the configuration library handles for the caller.) If the user settings are to be changed from their defaults, the script itself should provide a means to change them. This could be a (preferably optional) dialog box or any other mechanism the script author chooses.

User settings are saved in the user’s preferences folder (on Mac) or AppData folder (on Windows).

Merge Process

Files are merged into the passed-in list of default values. They do not replace the list. Each calling script contains a table of all the configurable parameters or settings it recognizes along with default values. An example:

sample.lua:

parameters = {
   x = 1,
   y = 2,
   z = 3
}

configuration.get_parameters(parameters, "script.config.txt")

for k, v in pairs(parameters) do
   print(k, v)
end

Suppose the script.config.text file is as follows:

y = 4
q = 6

The returned parameters list is:

parameters = {
   x = 1,       -- remains the default value passed in
   y = 4,       -- replaced value from the config file
   z = 3        -- remains the default value passed in
}

The q parameter in the config file is ignored because the input paramater list had no q parameter.

This approach allows total flexibility for the script add to or modify its list of parameters without having to worry about older configuration files or user settings affecting it.

Functions

get_parameters

configuration.get_parameters(file_name, parameter_list)

View source

Searches for a file with the input filename in the script_settings directory and replaces the default values in parameter_list with any that are found in the config file.

Input Type Description
file_name string the file name of the config file (which will be prepended with the script_settings directory)
parameter_list table a table with the parameter name as key and the default value as value
Return type Description
boolean true if the file exists

save_user_settings

configuration.save_user_settings(script_name, parameter_list)

View source

Saves the user’s preferences for a script from the values provided in parameter_list.

Input Type Description
script_name string the name of the script (without an extension)
parameter_list table a table with the parameter name as key and the default value as value
Return type Description
boolean true on success

get_user_settings

configuration.get_user_settings(script_name, parameter_list, create_automatically)

View source

Find the user’s settings for a script in the preferences directory and replaces the default values in parameter_list with any that are found in the preferences file. The actual name and path of the preferences file is OS dependent, so the input string should just be the script name (without an extension).

Input Type Description
script_name string the name of the script (without an extension)
parameter_list table a table with the parameter name as key and the default value as value
create_automatically (optional) boolean if true, create the file automatically (default is true)
Return type Description
boolean true if the file already existed, false if it did not or if it was created automatically