cs-py-modules 20250724

Convenience functions related to modules, packages and importing.

Convenience functions related to modules, packages and importing.

Latest release 20250724:

• Improve resolution of relative imports. (Fix seems to be an overly strong word here, unfortunately.)
• Drop pretence at Python 2 support.

Short summary:

• direct_imports: Crudely parse src_filename for import statements. Return the set of directly imported module names.
• import_extra: Try to import the package named extra_package_name using importlib.import_module.
• import_module_from_file: Import a specific file as a module instance, return the module instance.
• import_module_name: Import module_name and return the value of name within it.
• module_attributes: Generator yielding the names and values of attributes from a module which were defined in the module.
• module_files: Generator yielding .py pathnames involved in a module.
• module_names: Return a list of the names of attributes from a module which were defined in the module.

Module contents:

• direct_imports(src_filename, module_name): Crudely parse src_filename for import statements. Return the set of directly imported module names.

  Resolve relative imports against module_name.

  This is a very simple minded source parse.

• import_extra(extra_package_name, distinfo): Try to import the package named extra_package_name using importlib.import_module. Return the imported package.

  If an ImportError is raised, riffle through the extras mapping in distinfo['extras_requires'] for the package name, and emit an informative warning about the extras which require this package and whose use a pip install time would bring the package in. The original ImportError is then reraised.

  If no extra is found this is presumed to be an error by the caller and a RuntimeError is raised. This function is for internal use as:

  pkg = import_extra('some_package', DISTINFO)
  

  which passes in the source module's DISTINFO mapping, which I use as the basis for my package distributions.

  A fuller example from my cs.timeseries module's plot command line mode:

  def cmd_plot(self, argv):
    """ Usage: {cmd} datadir days fields...
    """
    try:
      import_extra('plotly', DISTINFO)
    except ImportError as e:
      raise GetoptError(
          "the plotly package is not installed: %s" % (e,)
      ) from e
  

  which produces this output:

  timeseries.py: plot: import_extra('plotly'): package not available; the following extras pull it in: ['plotting']
  timeseries.py: the plotly package is not installed: timeseries.py: plot: import_extra('plotly'): No module named 'plotly'
  

• import_module_from_file(module_name, source_file, sys_path=None): Import a specific file as a module instance, return the module instance.

  Parameters:

  • module_name: the name to assign to the module
  • source_file: the source file to load
  • sys_path: optional list of paths to set as sys.path for the duration of this import; the default is the current value of sys.path

  Note that this is a "bare" import; the module instance is not inserted into sys.modules.

  Warning: sys.path is modified for the duration of this function, which may affect concurrent applications.

• import_module_name(module_name, name=None, sys_path=None, lock=None): Import module_name and return the value of name within it.

  Parameters:

  • module_name: the module name to import.
  • name: optional name within the module whose value is returned; if name is None, return the module itself.
  • sys_pathoptional list of paths to use as sys.path during the import.
  • lock: an optional lock to hold during the import (recommended).

  Warning: sys.path is modified for the duration of this function, which may affect concurrent applications.

• module_attributes(M): Generator yielding the names and values of attributes from a module which were defined in the module.

• module_files(M): Generator yielding .py pathnames involved in a module.

• module_names(M): Return a list of the names of attributes from a module which were defined in the module.

Release Log

Release 20250724:

• Improve resolution of relative imports. (Fix seems to be an overly strong word here, unfortunately.)
• Drop pretence at Python 2 support.

Release 20241122: import_module_name: rename the path parameter to sys_path to match import_module_from_file, default sys_path to sys.path.

Release 20240630: direct_imports: fix off-by-one resolving leading dot relative import names.

Release 20220606: New import_extra(extra_package_name,distinfo) function to politely try to import a package which is associated with an extra.

Release 20210123: module_attributes: skip values from other modules if we know the module (computed values like tuples have no module and still need to be returned).

Release 20200521:

• New import_module_from_file function to import a Python file as a module instance.
• New direct_imports(src_filename,module_name=None) returning the set of directly imports module names.

Release 20190101: New functions: module_names, module_attributes.

Release 20160918:

• New generator function module_files yielding pathnames.
• import_module_name: accept name=None, just return the module.
• Add empty "install_requires" for DISTINFO completeness.

Release 20150116: Initial PyPI release.