Merge pull request #153 from braboj/codex/add-relative-import-example

Add relative import example

Author: braboj

examples/A10_modules/foo/__init__.py

@@ -0,0 +1,37 @@
+# Package demonstrating relative imports and an export decorator.
+# ------------------------------------------------------------------------------
+# Shows relative imports and how to define __all__.
+# Define the packet API
+__version__ = '1.0.0'
+
+# The dot(.) operator is used to import modules relative to the current package.
+# A single dot (.) refers to the current package.
+# Two dots (..) refer to the parent package.
+# Three dots (...) refer to the grandparent package, and so on.
+
+from .api.submodule1 import func1
+from .core.submodule2 import func2
+from .gui.submodule3 import func3
+
+
+# The __all__ variable is used to define the public API of a module or a package.
+__all__ = ['func1', 'func2', 'func3']
+
+
+# Export decorator
+def export(defn):
+
+    # Add the object to the global namespace
+    globals()[defn.__name__] = defn
+
+    # Set the object to be exported
+    __all__.append(defn.__name__)
+
+    # Return the object
+    return defn
+
+
+# Demonstration of the export decorator
+@export
+def func4():
+    print('func4')

examples/A10_modules/foo/__main__.py

@@ -0,0 +1,17 @@
+# Entry point executed when running the package with -m.
+# ------------------------------------------------------------------------------
+# Allows running the package directly as a script.
+import sys
+import os.path
+
+
+def main():
+    progname = sys.argv[0]
+    sys.argv[:] = sys.argv[1:]
+    sys.path.insert(0, os.path.dirname(progname))
+
+    print('sys.argv =', sys.argv)
+
+
+if __name__ == "__main__":
+    main()

examples/A10_modules/foo/api/__init__.py

@@ -0,0 +1,4 @@
+# API subpackage exposing a version constant.
+# ------------------------------------------------------------------------------
+# Holds version information for the API.
+__version__ = '0.1.0'

examples/A10_modules/foo/api/submodule1.py

@@ -0,0 +1,9 @@
+# Submodule used to demonstrate absolute and relative imports.
+# ------------------------------------------------------------------------------
+# Provides a function and constant for tests.
+# Define a constant
+my_id = 1
+
+
+def func1():
+    print('func1() from submodule1.py with my_id =', my_id)

examples/A10_modules/foo/core/__init__.py

@@ -0,0 +1,3 @@
+# Core subpackage used in import demonstrations.
+# ------------------------------------------------------------------------------
+# Core components used by the package.

examples/A10_modules/foo/core/submodule2.py

@@ -0,0 +1,9 @@
+# Submodule used in absolute import demonstrations.
+# ------------------------------------------------------------------------------
+# Supplies a second function and constant.
+# Define a constant
+my_id = 2
+
+
+def func2():
+    print('func2() from submodule2.py with my_id =', my_id)

examples/A10_modules/foo/gui/__init__.py

@@ -0,0 +1,3 @@
+# GUI subpackage used in import demonstrations.
+# ------------------------------------------------------------------------------
+# GUI layer that references the other submodules.

examples/A10_modules/foo/gui/submodule3.py

@@ -0,0 +1,9 @@
+# Submodule used by the GUI package for import demonstrations.
+# ------------------------------------------------------------------------------
+# Contains a GUI-specific function and constant.
+# Define a constant
+my_id = 3
+
+
+def func3():
+    print('func3() from submodule1.py with my_id =', my_id)

examples/A10_modules/import_absolute.py

@@ -0,0 +1,16 @@
+# Shows how to enforce and use absolute imports.
+# ------------------------------------------------------------------------------
+# Example script demonstrating absolute imports.
+from __future__ import absolute_import
+# Using absolute imports
+import asyncio
+
+# Absolute imports
+from foo.api.submodule1 import func1
+from foo.core.submodule2 import func2
+from foo.gui.submodule3 import func3
+
+# Call all functions
+func1()
+func2()
+func3()

examples/A10_modules/import_relative.py

@@ -0,0 +1,11 @@
+# Shows how to use relative imports within a package.
+# -----------------------------------------------------------------------------
+# Demonstrates importing modules from the current package using relative syntax.
+
+from .foo.api.submodule1 import func1
+from .foo.core.submodule2 import func2
+# Relative imports are scoped to packages.
+
+# Call the imported functions
+func1()
+func2()