Method: PyCall::Import#pyfrom

Defined in:
lib/pycall/import.rb

#pyfrom(mod_name, import: nil) ⇒ Object

This function is implemented as a mimic of import_from function defined in Python/ceval.c.

Raises:

  • (ArgumentError) 


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# File 'lib/pycall/import.rb', line 23

def pyfrom(mod_name, import: nil)
  raise ArgumentError, "missing identifier(s) to be imported" unless import

  mod_name = mod_name.to_str if mod_name.respond_to? :to_str
  mod_name = mod_name.to_s if mod_name.is_a? Symbol

  import = Array(import)
  fromlist = import.map.with_index do |import_name, i|
    case import_name
    when assoc_array_matcher
      import_name[0]
    when Symbol, String
      import_name
    else
      raise ArgumentError, "wrong type of import name #{import_name.class} (expected String or Symbol)"
    end
  end
  from_list = PyCall.tuple(from_list)

  main_dict_ptr = PyCall.import_module('__main__').__dict__.__pyptr__
  globals = main_dict_ptr # FIXME: this should mimic to `import_name` function defined in `Python/ceval.c`.
  locals = main_dict_ptr # FIXME: this should mimic to `import_name` function defined in `Python/ceval.c`.
  level = 0 # TODO: support prefixed dots (#25)
  mod = LibPython::Helpers.import_module(mod_name, globals, locals, fromlist, level)

  import.each do |import_name|
    case import_name
    when assoc_array_matcher
      name, asname = *import_name
    when Symbol, String
      name, asname = import_name, import_name
    end

    if PyCall::LibPython::Helpers.hasattr?(mod.__pyptr__, name)
      pyobj = PyCall::LibPython::Helpers.getattr(mod.__pyptr__, name)
      define_name(asname, pyobj)
      next
    end

    if mod.respond_to? :__name__
      pkgname = mod.__name__
      fullname = "#{pkgname}.#{name}"
      sys_modules = PyCall.import_module('sys').modules
      if sys_modules.has_key?(fullname)
        pyobj = module_dict[fullname]
        define_name(asname, pyobj)
        next
      end
    end

    raise ArgumentError, "cannot import name #{fullname}" unless pyobj
  end
end