How to serialize a complex interface with unexported fields?

I need to serialize some complex interfa开发者_如何学编程ce (template.Template). It has many unexported fields, and gob don't want to work with them. Any suggestions?

P.S. Actualy, I trying to put a parsed template to memcache on App Engine.

The short answer is that there's usually a reason for unexported fields--template.Template, for instance, contains information which changes during parsing--so I'd advise against serializing them yourself with reflect. However, the GobEncoder and GobDecoder interfaces were recently added to gob; if you need to serialize a complex struct with unexported fields, encourage the author of the package to implement these interfaces. Even better, implement them yourself (shouldn't be hard for template.Template) and contribute your patch.

If the type is from another package (such as template) this can't be done with any of the current serialization libs for Go (gob, json, bson, etc.). Nor should it be done, because the fields are unexported.

However, if you really need to, you can write your own serializer using package reflect, specifically Value.Field() and friends to get the unexported fields. Then you just need to store them in a way that you can decode later.