8  Coding Standards

Consistent style makes code easier to review, maintain, and contribute to. JASP enforces conventions for both R and QML code, as well as standardised option names that bridge the two.

8.1 R Style Guide

8.1.1 Naming

Element	Convention	Example
Functions	camelCase, verb + noun	computeMeanDifference()
Local variables	camelCase	effectSize
Constants	camelCase (same as variables)	maxIterations
Files	analysisname.R (lowercase)	ttestindependentsamples.R

8.1.2 Formatting

• Indentation: 2 spaces (no tabs).
• Line length: ≤ 120 characters.
• Assignment: Use <-, not =.
• Spacing: Space after commas, around operators (+, -, <-, ==), but not inside parentheses.
• Braces: Opening { on the same line; closing } on its own line.
• Strings: Use double quotes " consistently.

# Good
.computeResults <- function(jaspResults, dataset, options) {
  if (options[["meanDifference"]])
    table$addColumnInfo(name = "meanDiff", title = gettext("Mean Difference"), type = "number")
}

# Bad
.computeResults = function( jaspResults,dataset,options ){
  if(options[['meanDifference']])
    table$addColumnInfo(name='meanDiff',title=gettext('Mean Difference'),type='number')
}

8.1.3 Functions

• Internal (private) helper functions start with a dot: .computeResults().
• The main entry point (called from QML) is the only public function without a dot.
• Avoid deeply nested if/else chains — use early returns or helper functions.
• Use options[["optionName"]] (double brackets), never options$optionName.

8.1.4 Comments

• Use # followed by a space.
• Comment why, not what — the code itself should show what it does.

8.2 QML Style Guide

See the QML Style Example appendix for a full annotated form.

8.2.1 Formatting

• Indentation: Tabs (4-space width).
• Braces: Opening { on its own line, vertically aligned with the closing }.

// Good
Group
{
    title: qsTr("Options")
    CheckBox { name: "meanDifference"; label: qsTr("Mean difference") }

    IntegerField
    {
        name:         "ciWidth"
        label:        qsTr("Confidence interval")
        defaultValue: 95
        min:          50
        max:          99
    }
}

8.2.2 Property Alignment

When a QML element has multiple properties, align property values vertically:

IntegerField
{
    name:         "bootstrapSamples"
    label:        qsTr("Bootstrap samples")
    defaultValue: 1000
    min:          100
    max:          1000000
}

8.2.3 One-liner Elements

Simple elements with 1–3 short properties may go on a single line:

CheckBox { name: "meanDifference"; label: qsTr("Mean difference") }
CheckBox { name: "effectSize";     label: qsTr("Effect size")     }

When stacking one-liners, align property values across lines for readability.

8.2.4 Strings

Wrap all user-visible strings in qsTr() for translation (see Chapter 12).

8.3 Option Naming Conventions

Option names appear in QML (name: property), flow to R via options[["name"]], and persist in .jasp files. Consistent naming is essential for long-term compatibility.

8.3.1 Rules

1. camelCase — no underscores, no dots, no kebab-case.
2. Singular nouns — confidenceInterval, not confidenceIntervals.
3. Abbreviations are words — capitalise only the first letter: Ci, not CI; Bf, not BF; Mcmc, not MCMC.
4. Be specific but concise — descriptivesTableCi rather than ci when ambiguous.
5. Boolean options — name describes the thing being toggled, not the action: meanDifference (not showMeanDifference).

8.3.2 Common Standardised Names

Use these names wherever the concept applies — do not invent synonyms:

Concept	Standard Name
Confidence interval width	ciWidth
Credible interval width	credibleIntervalWidth
Descriptives table	descriptivesTable
Effect size	effectSize
Bayes factor direction	bayesFactorType
Missing values handling	missingValues
Sample sizes	sampleSize
Bootstrap samples	bootstrapSamples

See Appendix C for the full reference table.

8.3.3 Variable List Names

For AssignedVariablesList, name after the statistical role:

Role	Name
Dependent variable	dependent
Independent / fixed factors	fixedFactors
Random factors	randomFactors
Covariates	covariates
Grouping variable	groupingVariable
Repeated measures	repeatedMeasuresFactors
Weights	weights

8.4 Applying Standards in Practice

A practical workflow:

1. Before writing code: scan Appendix C for existing names that match your options.
2. During development: run a quick check — do your names follow camelCase, use singular nouns, and spell abbreviations as words?
3. During review: compare against this chapter. Reviewers will flag deviations.
4. When renaming: if an option name must change after release, provide an Upgrades.qml entry (see Chapter 13).