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Emit callbacks
Emit callbacks are invoked when an instance of a registered class is emitted by yaml_emit() or yaml_emit_file() . The callback is passed the object to be emitted. The callback must return an array having two keys: "tag" and "data". The value associated with the "tag" key must be a string to be used as the YAML tag in the output. The value associated with the "data" key will be encoded as YAML and emitted in place of the intercepted object.
Example #1 Emit callback example
<?php
class EmitExample {
public $data ; // data may be in any pecl/yaml suitable type
public function __construct ( $d ) {
$this -> data = $d ;
}
public static function yamlEmit ( EmitExample $obj ) {
return array(
'tag' => '!example/emit' ,
'data' => $obj -> data ,
);
}
}
$emit_callbacks = array(
'EmitExample' => array( 'EmitExample' , 'yamlEmit' )
);
$t = new EmitExample (array( 'a' , 'b' , 'c' ));
$yaml = yaml_emit (
array(
'example' => $t ,
),
YAML_ANY_ENCODING ,
YAML_ANY_BREAK ,
$emit_callbacks
);
var_dump ( $yaml );
?> 以上例程的输出类似于：
string(43) "--- example: !example/emit - a - b - c ... "