Contexter

A dirty piece of code for fetching context.Context from the stack when it cannot be passed normally.

But why?

I turned out to need access to context.Context from a MarshalJSON() method and found out there is no way to pass it easily. This is one of my attempts at passing ctx across the stack.

So if your method that accepts a context.Context calls json.Marshal(), it is likely the MarshalJSON() methods will be able to fetch the context using contexter.Context().

This said, we now have the pjson lib that accepts contextes and is able to cleanly pass the context to the encoded objects.

My soul doesn't hurt enough

More stack based golang dark magic can be found online:

• https://github.com/jtolio/gls

It doesn't work

There can be various reasons why this doesn't work, or stopped working.

• The method receiving a context.Context has been inlined and its parameters aren't available
• The variable containing the context.Context isn't used and was overwritten
• You're into a different goroutine (which means a new stack)
• Something changed in Go's runtime, stack display format, etc
• The architecture you're using does something that's not accounted for in this module

This is not an exact science, and using this package may result in the end of the world, or your program crashing in ways go can't recover. You've been warned.

Usage

ctx := contexter.Context()

This will automatically fetch the closest context.Context object found in the stack that was passed as a context.Context object, or nil if none were found.

var ctx context.Context
if contexter.Find(&ctx) {
	// use ctx
}

This alternative version can find other kind of interfaces on the stack.