HOCON supports multiple comment styles, giving flexibility in how do you document your settings.

Comments are sentences in Hocon configuration that allow users to read and understand the configuration better. Comments help to understand the configuration better and provide context to updates or add extra configuration.

Let’s see How to write comments in multiple ways.

  • Single Line Comments

    • Single Line comments always start with # or double slashes //,

    • All the text followed by # or // are comments, and ignored.

    • These comments are in new lines or inline

    • Hash Comments (#) The simple and easy to document any line in configuration using # symbol

# This is a single-line comment
database {
  host = "localhost"  # Inline comment briefs about database host
  port = 5432
}
  • Double Slash Comments (//)
// This is a single-line  valid comment
database {
  host = "localhost"  // Inline comment briefs about database host
  port = 5432
}
  • Multi-Line Comments

There are no multi-line comments supported, But you can prefix # or // on a new line. Commented lines do spans in multiple lines.

# Multi-line comment example
# Another multiple line
database = "mysql"
  • Inline Comments

Inline comments are placed at the end of a line. There is a space between value and comment syntax.

database = "mysql" # Inline comment
  • Block Comments:

There is no support for block comments syntax.

Comments are helpful for users to improve readability, but programs or parsers ignore the comment's text.

The below example shows all single, multi, and inline comment examples

# Single line comment
// Another way to write a Single line comment

database = "mysql" # Inline comment

# This is a multi-line comment
# that spans multiple lines
appname = "myapp"

# Comment actual key and pairs
# hostname = "localhost"


ssl = "true" # Inline comment

Tools for Working with HOCON Comments

Most of editors and IDE’s help you work more effectively with commented these configurations.

  • IDE plugins: Most modern IDE’s provides either inbuilt support or plugins that provides synax highlighting for comments

  • Linter tools: These tools does validation hocon syntx, while preserving comments.

  • Documentation Generators: Tools that generates documentation from this configuration files