sourceafIoc::MethodAdvisor.fan

**
** Passed into module advisor methods to allow the method to, err, advise services!
** 
** @see The `Advise` facet for more details.
** 
** @since 1.3.0
class MethodAdvisor {
    internal |MethodInvocation invocation -> Obj?|[] aspects    := [,]
    
    ** The method to advise
    const Method    method
    
    internal new make(Method method) {
        this.method = method
    }
    
    ** Add an aspect that will be called when the method is invoked
    Void addAdvice(|MethodInvocation invocation -> Obj?| aspect) {
        aspects.add(aspect)
    }

    // given I've never needed to override method advice (and realistically I'm the only one using 
    // afIoc!) we'll not order the advice for now
//  abstract Void addOrderedAdvice(Str id, Str[] orderingConstraints, |Obj target, Obj[] args| aspect)
//  abstract Void overrideOrderedAdvice(Str idToOverride, Str id, Str[] orderingConstraints, |Obj target, Obj[] args| aspect)
}

** As used by aspects to call the method they wrap.
** 
** The wrapped method is purposely hidden so no-one is tempted to call it directly, use [invoke()]`#invoke` instead.  
** The real method is hidden behind this class so multiple Method Advisors can be chained
** 
** @see The `Advise` facet for more details.
** 
** @since 1.3.0
class MethodInvocation {
    ** The instance of the service the method will be called on
    Obj     service
    
    ** A mutable list of arguments the method will be called with
    Obj?[]  args

    internal Method? method
    internal Int index
    internal |MethodInvocation invocation -> Obj?|[] aspects

    internal new make(|This|f) { f(this) }

    ** Call the next method advice in the pipeline, or the real method - you'll never know which!
    Obj? invoke() {
        index++
        if (index <= aspects.size)
            return aspects[-index].call(this)
        
        return method.callOn(service, args)
    }
}