[Zope3-dev] Re: zc.buildout: When is recipe.install run?

[Jim Fulton]

On Sep 12, 2006, at 9:03 AM, Martijn Faassen wrote:
...
> The 'svn update' usecase is the reason we could think of why  
> install is always called, even if recipe and buildout config hasn't  
> changed.
>
> Right now the install method can be called in a number of different  
> cases:
>
> a) when the part isn't there yet
>
> b) when the part is there, and the configuration or recipe has  
> changed. In this case the part is removed again automatically, so  
> this is equivalent to a).
>
> c) when the part is there, and the recipe and configuration have  
> not changed. In this case there needs to be code that bails out if  
> the part is there and looks okay, or alternatively update code that  
> updates the part (svn up).
>
> Case c) looks different. If there was an update method that got  
> called in case c), the install method wouldn't need to be called  
> anymore, and:
>
> * the install method can *always* assume the part isn't there and  
> that it needs to freshly install it.
>
> * the update method can *always* assume the part is already there  
> and it needs to be updated (if necessary).
>
> * we don't need to implement our 'bail-out' method in install anymore.

Let me mull that a bit.

Jim

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