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Subjects

JAVASCRIPTHTMLCSSPYTHONSQLJAVACPPCSHARPPHPTYPESCRIPTCRUBYGOSWIFTKOTLINRUSTRBASHSCALAOBJECTIVE-CDARTPERLLUAMATLABXMLJSONMARKDOWNASSEMBLYLATEXYAMLSOLIDITYBLOCKCHAIN

Topics

Introduction to YAML

What is YAMLYAML vs. JSON and XMLYAML Use CasesYAML File Extension

YAML Syntax Basics

YAML IndentationYAML CommentsYAML Key-Value PairsYAML StringsYAML NumbersYAML BooleansYAML Null Values

YAML Data Structures

YAML ListsYAML Nested ListsYAML DictionariesYAML Nested DictionariesYAML Complex Structures

YAML Advanced Features

YAML AnchorsYAML AliasesYAML Merge KeysYAML Block ScalarsYAML Folded ScalarsYAML Literal ScalarsYAML Multi-line Strings

YAML Data Types

YAML TimestampsYAML Binary DataYAML SetsYAML PairsYAML Omap

YAML Document Structure

YAML Multiple DocumentsYAML Document SeparatorsYAML DirectivesYAML Tags

YAML Best Practices

YAML Naming ConventionsYAML Formatting GuidelinesYAML Error HandlingYAML Version Compatibility

Working with YAML

YAML ParsingYAML GenerationYAML ValidationYAML in PythonYAML in RubyYAML in JavaScript

YAML in Configuration

YAML for App ConfigYAML in DockerYAML in KubernetesYAML in Ansible

YAML Security

YAML InjectionYAML Safe LoadingYAML Encryption

YAML Tools and Editors

YAML Online ValidatorsYAML IDE PluginsYAML Command-line Tools

YAML Directives

YAML directives are special instructions that provide metadata or processing information for YAML processors. They appear at the beginning of a YAML document and influence how the document is interpreted.

Purpose of YAML Directives

Directives serve several important functions in YAML:

  • Specify the YAML version being used
  • Define custom tag handles
  • Provide processing instructions to YAML parsers

Syntax and Usage

YAML directives always start with a percent sign (%) and must appear at the top of the document, before any content. They are followed by a space and then the directive name.

%YAML 1.2
%TAG !yaml! tag:yaml.org,2002:
---
# Document content starts here

Common YAML Directives

1. YAML Version Directive

The YAML version directive specifies which version of YAML the document uses. It's crucial for ensuring compatibility with different YAML processors.

%YAML 1.2
---
key: value

2. TAG Directive

The TAG directive is used to define shorthand notations for URI prefixes. This is particularly useful when working with custom data types or when referencing external schemas.

%TAG !xs! http://www.w3.org/2001/XMLSchema#
---
date: !xs!date 2023-05-15

Best Practices

  • Always specify the YAML version at the beginning of your document
  • Use TAG directives sparingly and only when necessary
  • Document any custom tag handles to ensure clarity for other developers
  • Be consistent with directive usage across related YAML files

Considerations

When working with YAML directives, keep the following points in mind:

  • Not all YAML processors support all directives
  • Directives are local to the document and do not affect other YAML files
  • Incorrect use of directives can lead to parsing errors

Understanding YAML directives is crucial for advanced YAML usage, especially when dealing with complex data structures or integrating with systems that require specific YAML configurations. For more information on related topics, explore YAML Tags and YAML Version Compatibility.