cs.py.modules 20220606

Convenience functions related to modules and importing.

Convenience functions related to modules and importing.

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

Function direct_imports(src_filename, module_name=None)

Crudely parse src_filename for import statements. Return the set of directly imported module names.

If module_name is not None, resolve relative imports against it. Otherwise, relative import names are returned unresolved.

This is a very simple minded source parse.

Function import_extra(extra_package_name, distinfo)

Try to import the package named extra_package_name using importlib.import_module and 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'

Function 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 multithreaded applications.

Function import_module_name(module_name, name, path=None, lock=None)

Import module_name and return the value of name within it.

Parameters:

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

Function module_attributes(M)

Generator yielding the names and values of attributes from a module which were defined in the module.

Function module_files(M)

Generator yielding .py pathnames involved in a module.

Function module_names(M)

Return a list of the names of attributes from a module which were defined in the module.

Release Log

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.