I am writing a library that could use the benefit of context, but I also want to add additional functionalities to the context my library using, while keeping the same golang idiom of using With*() to create a new context based off its parent.
At first, it seems that all I need to do is to satisfy the context.Context interface, but as I look deeper into the context.go source code (https://golang.org/src/context/context.go), it looks like that I wouldn't be able to benefit from parent's context, unless I reimplement some of the original context.Context features, in particular its cancelCtx. For example, the code WithDeadline() creates a context with a deadline, which is really just a timerCtx, whose parent is cancelCtx. The context package also has this function called "propagateCancel()" which worries me a bit as it looks like the parent context maintains a list of its children. So, if I want to create a new context with an additional feature, let's say WithFeatureX(context.Context, X), I cannot safely create a FeatureContext struct that can inherit from any previous contexts (possibly created from WithDeadline/WithCancel/WithTimeout) unless I also do the same thing as what propagateCancel() is doing. The parent context wouldn't know about the existence of FeatureContext unless I also duplicate the propagateCancel to include itself as a child. In other words, the relationship between the parent context and its children is hard-coded in the context package. My goal is to allow users of my library to specify their own context, either from Background() if they want just the basic, or WithTimeout() or WithCancel(), and then pass their context to library's own custom contexts WithFeatureX() or WithFeatureY() to add additional features, yet still retain its original parent's ability, whatever it is. It seems to me this is not possible without a lot of work and possibly access to the context package private functions. Could you guys please let me know if my analysis is correct that context.Context is not really designed for this purpose? Or am I just simply wrong and overlooking something obvious? Thanks! -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
