Traits 6.4 User Manual

Authors

David C. Morrill, Janet M. Swisher, and Enthought developers

Copyright

(C) Copyright 2005-2022 Enthought, Inc., Austin, TX

All rights reserved.

Contents

• Introduction
  • What Are Traits?
  • Background
• Installation
  • Installation from source on macOS
• Defining Traits: Initialization and Validation
  • A note about the Traits package structure
  • Predefined Traits
    • Predefined Traits for Simple Types
    • Other Predefined Traits
  • Trait Metadata
    • Internal Metadata Attributes
    • Recognized Metadata Attributes
    • Accessing Metadata Attributes
• Trait Notification
  • Via class definition
  • Via instance method
  • The expression Parameter
    • Traits Mini Language
    • Expressions as objects
  • Notification Handler
  • Features and fixes provided by observe()
    • Existence of observed items is checked by default
    • Arbitrarily nested containers are supported
    • observe() decorator can be stacked
    • Duplicated objects are now monitored
    • observe() is not idempotent
  • Migration from on_trait_change()
    • Observe extended trait names
    • Observe nested attributes in a container
    • Change handler signature is different
    • Syntax “[]” is not supported
    • Syntax “-” is not supported
    • Dispatch parameter differentiates observers
• Deferring Trait Definitions
  • DelegatesTo
  • PrototypedFrom
  • Keyword Parameters
    • Prefix Keyword
    • Listenable Keyword
  • Notification with Deferring
• Custom Traits
  • Trait Subclassing
    • Defining a Trait Type
    • Defining a Trait Property
    • Other TraitType Members
  • The Trait() Factory Function
    • Trait () Parameters
    • Mapped Traits
  • Trait Handlers
    • TraitPrefixList
    • TraitPrefixMap
  • Custom Trait Handlers
    • Example Custom Trait Handler
• Advanced Topics
  • Initialization and Validation Revisited
    • Dynamic Initialization
    • Overriding Default Values in a Subclass
    • Reusing Trait Definitions
    • Trait Attribute Definition Strategies
  • Interfaces
    • Defining an Interface
    • Implementing an Interface
    • Using Interfaces
  • Adaptation
    • Main features
    • Note on terminology
    • Defining Adapters
    • Adapter factories, and conditional adaptation
    • Requesting an adapter
    • Implementation details
    • Migration guide
    • Gotchas
    • Recommended readings about adaptation
  • Property Traits
    • Property Factory Function
    • Caching a Property Value
  • Persistence
    • Pickling HasTraits Objects
    • Predefined Transient Traits
    • Overriding __getstate__()
    • Unpickling HasTraits Objects
    • Overriding __setstate__()
  • Useful Methods on HasTraits
    • add_trait()
    • clone_traits()
    • trait_set()
    • add_class_trait()
  • Performance Considerations of Traits
• Testing
  • Testing Traits Classes
  • Using Mocks
• Tips for debugging Traits
  • Re-raising exceptions in change handlers
  • Tracing Traits Change Events
• Traits internals
  • Fundamentals
    • Key class: HasTraits
    • Key class: CTrait
    • Attribute retrieval
    • Attribute set operations
    • Attribute deletion
  • Traits Containers
    • Backwards Compatibility
    • Container Validators
    • Container Notifiers
• Appendix
  • Trait Notification with on_trait_change
  • Property depends_on

Indices and tables

• Index

• Search Page

License

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