René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"add_multi_constructor equivalent / unknown tag handler","articleBody":"In PyYAML, I can use the `add_multi_constructor` feature to allow me to define a constructor for multiple tags. I am using it to handle any unknown tags. For example, I could use this to deserialize the document\r\n```yaml\r\nthing1: !someTag asdf\r\nthing2: !someOtherTag fdsa\r\n```\r\n\r\ninto the JS structure\r\n```js\r\n{\r\n  thing1: UnknownTag { tag: 'someTag', value: 'asdf' },\r\n  thing2: UnknownTag { tag: 'someOtherTag', value: 'fdsa' }\r\n}\r\n```\r\n\r\nand be able to re-serialize that structure back into equivalent yaml.\r\n\r\nMy use case is to read and modify a tiny part of a big yaml file that has a bunch of domain-specific tags in it. I don't care how the tags are resolved as I'm not reading that part of the file, but currently with js-yaml I can't read it at all because to parse the file in the first place results in an unknown tag error. Even if I set it to skip unknown tags, I can't re-serialize the modified docjument.\r\n\r\nThis is fine with PyYAML as I can use `add_multi_constructor` as defined above to handle any unknown tags, but as far as I can tell this behvaiour is impossible to achieve with js-yaml.","author":{"url":"https://github.com/akdor1154","@type":"Person","name":"akdor1154"},"datePublished":"2017-12-06T02:03:21Z","url":"https://github.com/nodeca/js-yaml/issues/385"}