dart-modern-features

Name: dart-modern-features
Author: kevmoo

291installs16forks

How to install dart-modern-features?

kevmoo/dash_skills/dart-modern-features

$npx -y skills add kevmoo/dash_skills --skill dart-modern-features

Installs into the current project.

Summary

Guidelines for using modern Dart features (v3.0 - v3.10) such as Records, Pattern Matching, Switch Expressions, Extension Types, Class Modifiers, Wildcards, Null-Aware Elements, and Dot Shorthands.

Files · 1

View on GitHub

SKILL.md

1	# Dart Modern Features
2
3	## 1. When to use this skill
4
5	Use this skill when:
6	- Writing or reviewing Dart code targeting Dart 3.0 or later.
7	- Refactoring legacy Dart code to use modern, concise, and safe features.
8	- Looking for idiomatic ways to handle multiple return values, deep data
9	extraction, or exhaustive checking.
10
11	## Discovery
12
13	To find candidates for modernization:
14
15	### Switch Expressions
16	Search for switch statements where every case assigns to the same variable
17	or returns:
18	- Regex: `switch\s$[^)]+$\s\{\s*case`
19
20	### Pattern Matching Candidates
21	Search for manual map or JSON property extraction and type checking:
22	- Regex: `containsKey$['"][^'"]+['"]$`
23	- Regex: `json\[['"][^'"]+['"]\]\s+is\s+`
24
25	### Null-Aware Elements
26	Search for collection `if` statements checking for null:
27	- Regex: `if\s$\w+\s!=\snull$\s\w+`
28
29	### Digit Separators
30	Search for long numbers without separators:
31	- Regex: `\b\d{6,}\b` (Matches numbers with 6 or more digits).
32
33	## 2. Features
34
35	### Records
36	Use records as anonymous, immutable, aggregate structures to bundle multiple
37	objects without defining a custom class. Prefer them for returning multiple
38	values from a function or grouping related data temporarily.
39
40	Avoid:
41	Creating a dedicated class for simple multiple-value returns.
42	```dart
43	class UserResult {
44	final String name;
45	final int age;
46	UserResult(this.name, this.age);
47	}
48
49	UserResult fetchUser() {
50	return UserResult('Alice', 42);
51	}
52	```
53
54	Prefer:
55	Using records to bundle types seamlessly on the fly.
56	```dart
57	(String, int) fetchUser() {
58	return ('Alice', 42);
59	}
60
61	void main() {
62	var user = fetchUser();
63	print(user.$1); // Alice
64	}
65	```
66
67	### Patterns and Pattern Matching
68	Use patterns to destructure complex data into local variables and match against
69	specific shapes or values. Use them in `switch`, `if-case`, or variable
70	declarations to unpack data directly.
71
72	Avoid:
73	Manually checking types, nulls, and keys for data extraction.
74	```dart
75	void processJson(Map<String, dynamic> json) {
76	if (json.containsKey('name') && json['name'] is String &&
77	json.containsKey('age') && json['age'] is int) {
78	String name = json['name'];
79	int age = json['age'];
80	print('$name is $age years old.');
81	}
82	}
83	```
84
85	Prefer:
86	Combining type-checking, validation, and assignment into a single statement.
87	```dart
88	void processJson(Map<String, dynamic> json) {
89	if (json case {'name': String name, 'age': int age}) {
90	print('$name is $age years old.');
91	}
92	}
93	```
94
95	### Switch Expressions
96	Use switch expressions to return a value directly, eliminating bulky `case` and
97	`break` statements.
98
99	Avoid:
100	Using switch statements where every branch simply returns or assigns a value.
101	```dart
102	String describeStatus(int code) {
103	switch (code) {
104	case 200:
105	return 'Success';
106	case 404:
107	return 'Not Found';
108	default:
109	return 'Unknown';
110	}
111	}
112	```
113
114	Prefer:
115	Returning the evaluated expression directly using the `=>` syntax.
116	```dart
117	String describeStatus(int code) => switch (code) {
118	200 => 'Success',
119	404 => 'Not Found',
120	_ => 'Unknown',
121	};
122	```
123
124	### Class Modifiers
125	Use class modifiers (`sealed`, `final`, `base`, `interface`) to restrict how
126	classes can be used outside their defines library. Prefer `sealed` for defining
127	closed families of subtypes to enable exhaustive checking.
128
129	Avoid:
130	Using open `abstract` classes when the set of subclasses is known and fixed.
131	```dart
132	abstract class Result {}
133
134	class Success extends Result {}
135	class Failure extends Result {}
136
137	String handle(Result r) {
138	if (r is Success) return 'OK';
139	if (r is Failure) return 'Error';
140	return 'Unknown';
141	}
142	```
143
144	Prefer:
145	Using `sealed` to guarantee to the compiler that all cases are covered.
146	```dart
147	sealed class Result {}
148
149	class Success extends Result {}
150	class Failure extends Result {}
151
152	String handle(Result r) => switch(r) {
153	Success() => 'OK',
154	Failure() => 'Error',
155	};
156	```
157
158	### Extension Types
159	Use extension types for a zero-cost wrapper around an existing type. Use them to
160	restrict operations or add custom behavior without runtime overhead.
161
162	Avoid:
163	Allocating new wrapper objects just for domain-specific logic or type safety.
164	```dart
165	class Id {
166	final int value;
167	Id(this.value);
168	bool get isValid => value > 0;
169	}
170	```
171
172	Prefer:
173	Using extension types which compile down to the underlying type at runtime.
174	```dart
175	extension type Id(int value) {
176	bool get isValid => value > 0;
177	}
178	```
179
180	### Digit Separators
181	Use underscores (`_`) in number literals strictly to improve visual readability
182	of large numeric values.
183
184	Avoid:
185	Long number literals that are d

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dart-modern-features

291installs16forks

View on GitHub

How to install dart-modern-features?

kevmoo/dash_skills/dart-modern-features

$npx -y skills add kevmoo/dash_skills --skill dart-modern-features

Installs into the current project.

Summary

Guidelines for using modern Dart features (v3.0 - v3.10) such as Records, Pattern Matching, Switch Expressions, Extension Types, Class Modifiers, Wildcards, Null-Aware Elements, and Dot Shorthands.

Files · 1

View on GitHub

SKILL.md

1	# Dart Modern Features
2
3	## 1. When to use this skill
4
5	Use this skill when:
6	- Writing or reviewing Dart code targeting Dart 3.0 or later.
7	- Refactoring legacy Dart code to use modern, concise, and safe features.
8	- Looking for idiomatic ways to handle multiple return values, deep data
9	extraction, or exhaustive checking.
10
11	## Discovery
12
13	To find candidates for modernization:
14
15	### Switch Expressions
16	Search for switch statements where every case assigns to the same variable
17	or returns:
18	- Regex: `switch\s$[^)]+$\s\{\s*case`
19
20	### Pattern Matching Candidates
21	Search for manual map or JSON property extraction and type checking:
22	- Regex: `containsKey$['"][^'"]+['"]$`
23	- Regex: `json\[['"][^'"]+['"]\]\s+is\s+`
24
25	### Null-Aware Elements
26	Search for collection `if` statements checking for null:
27	- Regex: `if\s$\w+\s!=\snull$\s\w+`
28
29	### Digit Separators
30	Search for long numbers without separators:
31	- Regex: `\b\d{6,}\b` (Matches numbers with 6 or more digits).
32
33	## 2. Features
34
35	### Records
36	Use records as anonymous, immutable, aggregate structures to bundle multiple
37	objects without defining a custom class. Prefer them for returning multiple
38	values from a function or grouping related data temporarily.
39
40	Avoid:
41	Creating a dedicated class for simple multiple-value returns.
42	```dart
43	class UserResult {
44	final String name;
45	final int age;
46	UserResult(this.name, this.age);
47	}
48
49	UserResult fetchUser() {
50	return UserResult('Alice', 42);
51	}
52	```
53
54	Prefer:
55	Using records to bundle types seamlessly on the fly.
56	```dart
57	(String, int) fetchUser() {
58	return ('Alice', 42);
59	}
60
61	void main() {
62	var user = fetchUser();
63	print(user.$1); // Alice
64	}
65	```
66
67	### Patterns and Pattern Matching
68	Use patterns to destructure complex data into local variables and match against
69	specific shapes or values. Use them in `switch`, `if-case`, or variable
70	declarations to unpack data directly.
71
72	Avoid:
73	Manually checking types, nulls, and keys for data extraction.
74	```dart
75	void processJson(Map<String, dynamic> json) {
76	if (json.containsKey('name') && json['name'] is String &&
77	json.containsKey('age') && json['age'] is int) {
78	String name = json['name'];
79	int age = json['age'];
80	print('$name is $age years old.');
81	}
82	}
83	```
84
85	Prefer:
86	Combining type-checking, validation, and assignment into a single statement.
87	```dart
88	void processJson(Map<String, dynamic> json) {
89	if (json case {'name': String name, 'age': int age}) {
90	print('$name is $age years old.');
91	}
92	}
93	```
94
95	### Switch Expressions
96	Use switch expressions to return a value directly, eliminating bulky `case` and
97	`break` statements.
98
99	Avoid:
100	Using switch statements where every branch simply returns or assigns a value.
101	```dart
102	String describeStatus(int code) {
103	switch (code) {
104	case 200:
105	return 'Success';
106	case 404:
107	return 'Not Found';
108	default:
109	return 'Unknown';
110	}
111	}
112	```
113
114	Prefer:
115	Returning the evaluated expression directly using the `=>` syntax.
116	```dart
117	String describeStatus(int code) => switch (code) {
118	200 => 'Success',
119	404 => 'Not Found',
120	_ => 'Unknown',
121	};
122	```
123
124	### Class Modifiers
125	Use class modifiers (`sealed`, `final`, `base`, `interface`) to restrict how
126	classes can be used outside their defines library. Prefer `sealed` for defining
127	closed families of subtypes to enable exhaustive checking.
128
129	Avoid:
130	Using open `abstract` classes when the set of subclasses is known and fixed.
131	```dart
132	abstract class Result {}
133
134	class Success extends Result {}
135	class Failure extends Result {}
136
137	String handle(Result r) {
138	if (r is Success) return 'OK';
139	if (r is Failure) return 'Error';
140	return 'Unknown';
141	}
142	```
143
144	Prefer:
145	Using `sealed` to guarantee to the compiler that all cases are covered.
146	```dart
147	sealed class Result {}
148
149	class Success extends Result {}
150	class Failure extends Result {}
151
152	String handle(Result r) => switch(r) {
153	Success() => 'OK',
154	Failure() => 'Error',
155	};
156	```
157
158	### Extension Types
159	Use extension types for a zero-cost wrapper around an existing type. Use them to
160	restrict operations or add custom behavior without runtime overhead.
161
162	Avoid:
163	Allocating new wrapper objects just for domain-specific logic or type safety.
164	```dart
165	class Id {
166	final int value;
167	Id(this.value);
168	bool get isValid => value > 0;
169	}
170	```
171
172	Prefer:
173	Using extension types which compile down to the underlying type at runtime.
174	```dart
175	extension type Id(int value) {
176	bool get isValid => value > 0;
177	}
178	```
179
180	### Digit Separators
181	Use underscores (`_`) in number literals strictly to improve visual readability
182	of large numeric values.
183
184	Avoid:
185	Long number literals that are d

People who liked this also viewed

6 picks

Type