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From: "Joseph L. Casale" <jcasale@activenetwerx.com>
To: "Sven R. Kunze" <srkunze@mail.de>, "python-list@python.org" <python-list@python.org>
Subject: Re: Writing a module to abstract a REST api
Thread-Topic: Writing a module to abstract a REST api
Thread-Index: AQHQ8VdKzAS7nkl7nU2AayZu81Yu155BmmuAgADNE1WAAI/JAP//2Vfo
Date: Fri, 18 Sep 2015 21:43:13 +0000
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Hi Sven,=0A=
=0A=
>> The problem now comes from the following:=0A=
>>=0A=
>> # foo now contains a handle to the remote api.=0A=
>> foo =3D InstanceOfApiWrapper()=0A=
>=0A=
> Is it necessary to have an instance of that API? Just curiosity here.=0A=
=0A=
Not always but often as the pattern here might rely on a handle=0A=
to a c types based api handle for example which might be a pointer=0A=
or it may hold a session with credentials and state (not for REST of course=
).=0A=
=0A=
>> # queues is a container of Queue classes.=0A=
>> queues =3D foo.get_queues()=0A=
>>=0A=
>> queue =3D queues[0]=0A=
>> queue.delete()=0A=
>=0A=
> Alright. I see you want to have concrete classes, so you work with HTTP=
=0A=
> like you would do with SOAP-bases web services.=0A=
=0A=
Yup.=0A=
=0A=
> I actually was referring to the self-expanding capability of REST=0A=
> (please note, REST is not HTTP, HTTP is one protocol that can be use to=
=0A=
> build an REST-ful API). It's basically like: you query a resource which=
=0A=
> holds an link to another resource which you then you query by following=
=0A=
> that link and so on and so forth. So, all what you need for REST is one=
=0A=
> starting point to explore the resource graph.=0A=
=0A=
Well that is true, but what of the credential object that gets created=0A=
with the instance of InstanceOfApiWrapper? You are certainly right=0A=
in that the instance of Queue being REST based will always have all=0A=
it needs to perform the functions, it just lacks the credentials.=0A=
=0A=
>> In this case its possible for foo (InstanceOfApiWrapper) to inject a ref=
erence=0A=
>> to itself so the delete() can actually make the call.=0A=
>>=0A=
>> # I want to create a queue from scratch...=0A=
>> disparate_queue =3D Queue(x, y, z)=0A=
>> # Now what happens? No handle to an api?=0A=
>> disparate_queue.delete()=0A=
>=0A=
> I don't see an issue here. Looks quite readable.=0A=
=0A=
Well, what credentials does .delete() use? I should have actually stated=0A=
that, sorry.=0A=
=0A=
>> An alternative is:=0A=
>> foo.delete_queue(disparate_queue)=0A=
>>=0A=
>> That's not a pattern I prefer, what facilities in Python provide for a w=
orkaround=0A=
>> here?=0A=
>=0A=
> You always can add attributes to objects. So, add something like an=0A=
> __api__ attribute (which nobody would ever use except you when creating=
=0A=
> these queue objects in "get_queues").=0A=
=0A=
This is where I am going, but how do you perform dependency injection=0A=
in Python? =0A=
=0A=
> It's perfectly fine to add a "secret" API instance to the object. It's=0A=
> called aspect-oriented programming. You remove the aspect of how to=0A=
> correctly manage an API instance and put that knowledge into a separate=
=0A=
> piece of code. *thumbs up*=0A=
=0A=
Yea, I am glad you agree:) Its a model I certainly subscribe to. I just don=
't=0A=
know how to make the disparate case "know" of the foo instance when=0A=
foo didn't instantiate it (which gives the injection opportunity).=0A=
=0A=
That foo instance also serves of a starting point to make the GET type quer=
ies.=0A=
=0A=
How would you go about making disparate case lookup a handle, especially=0A=
when I insist on placing all the objects in their files. I know, tough to d=
o in=0A=
Python, but its what I am used to.=0A=
=0A=
Thanks a lot for the knowledge and insight, I greatly appreciate this.=0A=
jlc=