ViewText Documentation

Declarative text grid layouts from structured data

ViewText is a lightweight Python library for building dynamic text-based grid layouts. It provides a simple, declarative way to map structured data to formatted text output through a flexible registry and layout system.

Features

• Field Registry: Register data getters that extract values from context objects

• Formatter System: Built-in formatters for text, numbers, prices, dates, and relative times

• Layout Engine: TOML-based layout definitions that map fields to grid positions

• Extensible: Easy to add custom fields and formatters for domain-specific needs

Use Cases

• Terminal/CLI dashboards

• E-ink/LCD displays

• Text-based data visualization

• Any scenario requiring structured text layouts

Quick Example

from viewtext import LayoutEngine, LayoutLoader, BaseFieldRegistry

# Define your field registry
registry = BaseFieldRegistry()
registry.register("temperature", lambda ctx: ctx["temp"])

# Load layout from TOML
loader = LayoutLoader("layouts.toml")
layout = loader.get_layout("weather")

# Build grid output
engine = LayoutEngine(field_registry=registry)
lines = engine.build_line_str(layout, {"temp": 72})

Installation

This library is currently embedded in projects. Future: standalone PyPI package.

Contents

• Quickstart Guide
  • Installation
  • Basic Concepts
  • Simple Example
  • Computed Fields
  • Using Built-in Formatters
  • Using Python Field Registry (Advanced)
  • Next Steps
• User Guide
  • Field Registry
  • Formatter System
  • Layout Configuration
  • Layout Engine
  • Field Validation
  • Computed Fields
  • Layout Loader
  • Error Handling
  • Best Practices
  • Command Line Interface
  • Advanced Usage
  • TOML Schema Validation
• Fields Reference
  • Overview
  • Field Definition Structure
  • Field Types
  • Common Parameters
  • Validation Parameters
  • Computed Field Parameters
  • Context Key Resolution
  • Complete Examples
  • Best Practices
  • Common Patterns
  • CLI Commands for Fields
  • See Also
• Field Validation Reference
  • Overview
  • Validation Parameters
  • Error Handling Strategies
  • Type Validation Details
  • Examples
  • Validating Configuration
  • Testing Field Validation
  • Best Practices
  • Common Patterns
  • See Also
• Computed Fields Reference
  • Overview
  • Common Parameters
  • Temperature Conversions
  • Arithmetic Operations
  • Aggregate Operations
  • Mathematical Operations
  • String Operations
  • Conditional Operations
  • Error Handling
  • Best Practices
  • Examples by Use Case
• Formatters Reference
  • Overview
  • Common Usage
  • Built-in Formatters
  • Custom Formatters
  • Formatter vs Computed Field Operation
  • Formatter Presets
  • Best Practices
  • Examples by Use Case
  • See Also
• Testing Guide
  • Testing with TOML Configurations
  • Complete Test Example
  • Key Testing Patterns
  • Running Tests
  • Best Practices
• API Reference
  • viewtext.registry
  • viewtext.engine
  • viewtext.formatters
  • viewtext.loader
  • viewtext.validator
  • viewtext.registry_builder
• Examples
  • Weather Dashboard
  • Cryptocurrency Ticker
  • System Monitor
  • E-Commerce Product Display
  • Array Indexing and Nested Data
  • Dictionary Layout Example
  • Custom Formatter Example

Indices and tables

• Index

• Module Index

• Search Page