Doc coverage for paths, extensions inconsistent

[atc0005]

README says:

• extensions

  • mentions that the default is an empty list

• paths

  • mentions N/A for the default list

Code says:

elbow/config/config.go

Line 59 in 6945786

Paths []string `toml:"paths" arg:"--paths,env:ELBOW_PATHS" help:"List of comma or space-separated paths to process."`

elbow/config/config.go

Line 48 in 6945786

FileExtensions []string `toml:"file_extensions" arg:"--extensions,env:ELBOW_EXTENSIONS" help:"Limit search to specified file extensions. Specify as space separated list to match multiple required extensions."`

---

elbow/config/get.go

Lines 134 to 141 in 6945786

	// GetPaths returns the paths field if it's non-nil, app default value
	// otherwise
	func (c *Config) GetPaths() []string {
	if c == nil || c.Paths == nil {
	return nil
	}
	return c.Paths
	}

elbow/config/get.go

Lines 73 to 87 in 6945786

	// GetFileExtensions returns the fileExtensions field if it's non-nil, zero value
	// otherwise.
	// TODO: Double check this one; how should we safely handle returning an
	// empty/zero value?
	// As an example, the https://github.com/google/go-github package has a
	// `Issue.GetAssignees()` method that returns nil if the `Issue.Assignees`
	// field is nil. This seems to suggest that this is all we really can do here?
	//
	func (c *Config) GetFileExtensions() []string {
	if c == nil || c.FileExtensions == nil {
	// FIXME: Isn't the goal to avoid returning nil?
	return nil
	}
	return c.FileExtensions
	}

[atc0005]

This will probably be a lot clearer once I refactor the config handling to match more recent projects such as atc0005/dnsc or atc0005/check-cert. In those projects the config setup attempts to retrieve a user-provided value and if not found falls back to an explicit default for each configuration setting.

While a little more work to setup initially, it makes the "getter" methods consistent and provides a stable point of reference when updating configuration setting documentation (such as discussed here).

[atc0005]

See also the Configuration File section of the README where Multi-line array note is listed for one setting, but not the other.