Complex classes like Formatter often do a lot of different things. To break such a class down, we need to identify a cohesive component within that class. A common approach to find such a component is to look for fields/methods that share the same prefixes, or suffixes. You can also have a look at the cohesion graph to spot any un-connected, or weakly-connected components.
Once you have determined the fields that belong together, you can apply the Extract Class refactoring. If the component makes sense as a sub-class, Extract Subclass is also a candidate, and is often faster.
While breaking up the class, it is a good idea to analyze how other classes use Formatter, and based on these observations, apply Extract Interface, too.
1 | <?php |
||
11 | class Formatter implements FormatTokens |
||
12 | { |
||
13 | /** |
||
14 | * Map of tokens to formatting function names |
||
15 | */ |
||
16 | private const TOKEN_MAP = [ |
||
17 | self::TOKEN_DATE_CENTURY => 'formatCentury', |
||
18 | self::TOKEN_SERIAL_PRE => 'formatSerialPre', |
||
19 | self::TOKEN_SERIAL_POST => 'formatSerialPost', |
||
20 | self::TOKEN_DELIMITER => 'formatDelimiter', |
||
21 | self::TOKEN_CHECK_DIGIT => 'formatCheckDigit', |
||
22 | self::TOKEN_SEX => 'formatSex', |
||
23 | self::TOKEN_AGE => 'formatAge', |
||
24 | self::TOKEN_LEGAL_FORM => 'formatLegalForm', |
||
25 | self::TOKEN_BIRTH_COUNTY => 'formatBirthCounty', |
||
26 | ]; |
||
27 | |||
28 | /** |
||
29 | * @var \Closure Formatting function, takes an Id object and returns a string |
||
30 | */ |
||
31 | private $formatter; |
||
32 | |||
33 | /** |
||
34 | * Create formatter from format string |
||
35 | */ |
||
36 | public function __construct(string $format = '') |
||
89 | 6 | ||
90 | /** |
||
91 | * Format id using registered formatting functions |
||
92 | */ |
||
93 | public function format(IdInterface $idObject): string |
||
97 | |||
98 | /** |
||
99 | 6 | * Function must take an Id object and return a string |
|
100 | * |
||
101 | 6 | * @param mixed $formatter |
|
102 | 6 | */ |
|
103 | 6 | private function registerFormattingFunction($formatter): void |
|
114 | |||
115 | 6 | private function formatCentury(IdInterface $idObject): string |
|
123 | |||
124 | private function formatSerialPre(IdInterface $idObject): string |
||
128 | |||
129 | private function formatSerialPost(IdInterface $idObject): string |
||
133 | |||
134 | private function formatDelimiter(IdInterface $idObject): string |
||
138 | 1 | ||
139 | private function formatCheckDigit(IdInterface $idObject): string |
||
143 | |||
144 | private function formatSex(IdInterface $idObject): string |
||
148 | |||
149 | 1 | private function formatAge(IdInterface $idObject): string |
|
153 | |||
154 | private function formatLegalForm(IdInterface $idObject): string |
||
158 | 1 | ||
159 | private function formatBirthCounty(IdInterface $idObject): string |
||
163 | } |
||
164 |