library spatch

mindplay/spatch

Recursive dispatch and delivery

mindplay/spatch

This library is more about defining the flow of dispatch and delivery in a web application, more so than actually implementing anything., _(*1)

The goal is to separate the output of headers and content from any other activities that do not produce output., _(*2)

There are three important reasons to enforce this separation:, _(*3)

1. Separation: it is easier to understand code that deals exclusively with output or behavior, never with both., _(*4)

2. Control: avoid PHP gotchas where some operation caused output to start prematurely, preventing you from sending a header or setting session a variable, etc., _(*5)

3. Testing: separation enables testing in stages, e.g. testing the result of dispatch, such as the selected view-template and variables, versus actually testing what gets rendered., _(*6)

Two interfaces define a pair of concepts: two types of result which may be returned e.g. by action-methods in controllers:, _(*7)

• Dispatchable results do not send headers or content - they simply dispatch and perform whatever action it is they perform, which could be anything, as long as it doesn't cause any headers or content to be output., _(*8)

• Deliverable results actually deliver the result, which means sending headers and/or content - this could be anything, from a simple HTTP status code for redirection, to rendering a view or sending an image or file., _(*9)

The two interfaces as such are similar - Dispatchable::dispatch() should return either another Dispatchable, or a Deliverable, whereas Deliverable::deliver() should return nothing and produce a response., _(*10)

A simple Dispatcher class is included, which will accept a Dispatchable or Deliverable - it will dispatch() until a final Deliverable is returned, and then finally deliver() the result., _(*11)

The dispatcher enforces separation and flow by throwing an exception if the final result is not a Deliverable, and it will also throw if a Dispatchable produces any output prematurely., _(*12)

This may be easier to understand by actually reading the source code of the Dispatcher which is just a few lines of code., _(*13)