On Sat, 6 Mar 2021 14:06:27 +0100
Peter Otten <__pete...@web.de> wrote:
> On 06/03/2021 12:43, Manfred Lotz wrote:
> > On Sat, 6 Mar 2021 12:00:33 +0100
> > Manfred Lotz <ml_n...@posteo.de> wrote:
> >
> >> Let us say I have a package which reads a TOML file.
> >>
> >> I want to give the user of my package the choice to decide if he
> >> wants to use the toml, tomlkit or rtoml package.
> >>
> >> So, in case the user chose to use rtoml then there should be an
> >> import only for rtoml, aso.
> >>
> >> How could I achieve this?
> >>
> >
> > I got the following minimal example working but presumably my
> > solution isn't the best way.
> >
> > xtoml.py:
> >
> > class Xtoml:
> > def __init__(self, which='rtoml'):
> > self.which = which
> >
> > def parse_toml(self, toml_string):
> > if self.which == 'rtoml':
> > import rtoml as toml
> > elif self.which == 'tomlkit':
> > import tomlkit as toml
> > else:
> > import toml
> >
> > return toml.loads(toml_string)
> >
> >
> > test_xtoml.py:
> >
> > from xtoml import Xtoml
> >
> > toml_string = """
> > [default]
> >
> > basedir = "/myproject"
> >
> > """
> >
> > def main():
> > xtoml = Xtoml('toml')
> > parsed_toml = xtoml.parse_toml(toml_string)
> > print(parsed_toml)
> >
> > xtoml = Xtoml()
> > parsed_toml = xtoml.parse_toml(toml_string)
> > print(parsed_toml)
> >
> > if __name__ == "__main__":
> > main()
>
> As long as you use a common subset of the functions provided by the
> packages you can just do
>
Yes, this is a prereq. Otherwise, it wouldn't make sense to do this.
> def main():
> global toml # if you want to use the toml package elsewhere
> # in your module
>
> chosen_toml = ... # get package name
> toml = importlib.import_module(chosen_toml)
>
> data = toml.loads(toml_string)
>
> However, the user usually doesn't care, so I would recommend that you
> be bold and pick the package you prefer ;)
>
Exactly. This is why there is a default.
Using your suggestion my minimal example now looks like follows
xtoml.py:
import importlib
class Xtoml:
def __init__(self, which='rtoml'):
self.toml = importlib.import_module(which)
def parse_toml(self, toml_string):
return self.toml.loads(toml_string)
No change in test_xtoml.py.
Thanks a lot for your help.
--
Manfred
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