An Alternative idea to styling Text widgets

modified_text.dart

/// How to use
///
/// ModifiedText(
///   "hello",
///   modifier: TextModifiers.fontSize(50).bold.primaryColor,
/// )
class ModifiedText extends StatelessWidget {
  const ModifiedText(this.data, {Key? key, this.modifier = TextModifiers}) : super(key: key);

  final String data;
  final TextModifierBuilder modifier;

  @override
  Widget build(BuildContext context) => Text(data, style: modifier(context));
}

text_modifiers.dart

import 'package:flutter/material.dart';

/// How to use
///
/// Text(
///   "hello",
///   TextModifiers.fontSize(50).bold.primaryColor(context)
/// )
// ignore: constant_identifier_names
const TextModifiers = TextModifierBuilder();

typedef TextModifier = TextStyle Function(TextStyle style, ThemeData theme);

class TextModifierBuilder {
  const TextModifierBuilder([this._modifiers = const <TextModifier>[]]);

  final List<TextModifier> _modifiers;

  TextStyle call(BuildContext context) => build(context);

  TextStyle build(BuildContext context) {
    final theme = Theme.of(context);
    return _modifiers.fold(const TextStyle(), (style, modifier) => modifier(style, theme));
  }

  TextModifierBuilder append(TextModifier modifier) =>
      TextModifierBuilder([..._modifiers, modifier]);

  TextModifierBuilder prepend(TextModifier modifier) =>
      TextModifierBuilder([modifier, ..._modifiers]);
}

extension TextModifiersExtensions on TextModifierBuilder {
  TextModifierBuilder get bold => append((style, _) => style.copyWith(fontWeight: FontWeight.bold));

  TextModifierBuilder get primaryColor =>
      append((style, theme) => style.copyWith(color: theme.colorScheme.primary));

  TextModifierBuilder fontSize(double fontSize) =>
      append((style, _) => style.copyWith(fontSize: fontSize));
}

text_modifiers_alt.dart

import 'package:flutter/material.dart';

// ignore: constant_identifier_names
const TextModifiers = TextModifierBuilder();

class TextModifierContext {
  const TextModifierContext({required this.style});

  final TextStyle style;

  TextModifierContext copyWith({TextStyle? style}) =>
      TextModifierContext(style: style ?? this.style);
}

typedef TextModifier = TextModifierContext Function(TextModifierContext style, ThemeData theme);

class TextModifierBuilder {
  const TextModifierBuilder([this._modifiers = const <TextModifier>[]]);

  final List<TextModifier> _modifiers;

  TextModifierContext call(BuildContext context) => build(context);

  TextModifierContext build(BuildContext context) {
    final theme = Theme.of(context);
    return _modifiers.fold(
      const TextModifierContext(style: TextStyle()),
      (context, modifier) => modifier(context, theme),
    );
  }

  TextModifierBuilder append(TextModifier modifier) =>
      TextModifierBuilder([..._modifiers, modifier]);
}

extension TextModifiersExtensions on TextModifierBuilder {
  TextModifierBuilder get bold => append(
      (context, _) => context.copyWith(style: context.style.copyWith(fontWeight: FontWeight.bold)));

  TextModifierBuilder get primaryColor => append((context, theme) =>
      context.copyWith(style: context.style.copyWith(color: theme.colorScheme.primary)));

  TextModifierBuilder fontSize(double fontSize) =>
      append((context, _) => context.copyWith(style: context.style.copyWith(fontSize: fontSize)));
}

text_modifiers_alt2.dart

import 'package:flutter/material.dart';

/// How to use
///
/// Text(
///   "hello",
///   TextModifiers.from(context).fontSize(50).bold.primaryColor()
/// )
class TextModifiers {
  static TextModifierBuilder from(BuildContext context) => TextModifierBuilder(Theme.of(context));
}

typedef TextModifier = TextStyle Function(TextStyle style, ThemeData theme);

class TextModifierBuilder {
  TextModifierBuilder(this._themeData, [this._modifiers = const <TextModifier>[]]);

  final ThemeData _themeData;
  final List<TextModifier> _modifiers;

  TextStyle call() => build();

  TextStyle build() =>
      _modifiers.fold(const TextStyle(), (style, modifier) => modifier(style, _themeData));

  TextModifierBuilder append(TextModifier modifier) =>
      TextModifierBuilder(_themeData, [..._modifiers, modifier]);

  TextModifierBuilder prepend(TextModifier modifier) =>
      TextModifierBuilder(_themeData, [modifier, ..._modifiers]);
}

extension TextModifiersExtensions on TextModifierBuilder {
  TextModifierBuilder get bold => append((style, _) => style.copyWith(fontWeight: FontWeight.bold));

  TextModifierBuilder get primaryColor =>
      append((style, theme) => style.copyWith(color: theme.colorScheme.primary));

  TextModifierBuilder fontSize(double fontSize) =>
      append((style, _) => style.copyWith(fontSize: fontSize));
}