Automatic import ?
in [Python]
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From: C. B. on 25 Mar 2010 21:03 Hi everyone, I'm currently coding a C library which provides several modules and objects. Let's say that some of these objects are classes called AAA and BBB. The constructor of AAA needs to get BBB as argument. So I can run the following code : from mymodule import AAA from mymodule import BBB a = AAA(BBB())) But, as there is no case where AAA can be used without BBB, I would like to avoid importing BBB in my Python scripts when I already import AAA. For now, I think that reproducing the behavior of the __init__.py file could be a good way to do this, but how can I code that using only the C API ? Are there any other solutions ? Is this kind of importation a good idea ? Greetings, Cyrille Bagard
From: Steven D'Aprano on 26 Mar 2010 00:20 On Thu, 25 Mar 2010 18:03:58 -0700, C. B. wrote: > Hi everyone, > > I'm currently coding a C library which provides several modules and > objects. > > Let's say that some of these objects are classes called AAA and BBB. The > constructor of AAA needs to get BBB as argument. > > So I can run the following code : > > from mymodule import AAA > from mymodule import BBB > > a = AAA(BBB())) > > But, as there is no case where AAA can be used without BBB, I would like > to avoid importing BBB in my Python scripts when I already import AAA. Since AAA must take an argument of BBB, then give it a default: # in mymodule def AAA(arg=BBB()): ... # in another module from mymodule import AAA a = AAA() Or do this: from mymodule import AAA, BBB a = AAA(BBB()) > For now, I think that reproducing the behavior of the __init__.py file > could be a good way to do this, but how can I code that using only the C > API ? What is the behaviour of the __init__.py file? -- Steven
From: C. B. on 26 Mar 2010 04:15 > > What is the behaviour of the __init__.py file? > Not yet used, but I read this file is run by Python when a module of a package is imported. So you can insert default importations in it.
From: Ovidiu Deac on 26 Mar 2010 07:14 > But, as there is no case where AAA can be used without BBB, I would > like to avoid importing BBB in my Python scripts when I already import > AAA. Then why do you need to explicitely pass BBB() to AAA constructor? You could leave AAA constructor with no parameters or with a parameter with a default BBB() value
From: Jean-Michel Pichavant on 26 Mar 2010 08:35
C. B. wrote: > Hi everyone, > > I'm currently coding a C library which provides several modules and > objects. > > Let's say that some of these objects are classes called AAA and BBB. > The constructor of AAA needs to get BBB as argument. > > So I can run the following code : > > from mymodule import AAA > from mymodule import BBB > > a = AAA(BBB())) > > But, as there is no case where AAA can be used without BBB, I would > like to avoid importing BBB in my Python scripts when I already import > AAA. > > For now, I think that reproducing the behavior of the __init__.py file > could be a good way to do this, but how can I code that using only the > C API ? > > Are there any other solutions ? Is this kind of importation a good > idea ? > > Greetings, > Cyrille Bagard > Make AAA do the call to BBB: def AAA(*args, **kwargs): param = BBB(*args, **kwargs) # more code from mymodule import AAA AAA(1,2,3) # list of parameters you would have used with BBB. Saying that, is there any strong reason (meaning design issue) why you don't want to import explicitly BBB ? Because if the reason is 'It takes too much time', then it's a bad reason. Cheers, JM |