package version section

README.md

@@ -9,10 +9,11 @@ sites.
 ## Why packages?
 
 When working on your project, you typically end up with some scripts,
-functions and classes that are of more general interest. As a first
-step, you make some modules, i.e. separate python files, where you
-collect this code. These modules can be easily imported from other
-scripts in the very same directory.
+functions and classes that could be of more general interest. For
+example, if you would use this code in some other projects as well.
+As a first step, you make some modules, i.e. separate python files,
+where you collect this code. These modules can be easily imported from
+other scripts in the very same directory.
 
 For example, consider a module `addition.py` and a script `analyze.py`
 both in the same directory:
@@ -46,7 +47,7 @@ people, you need to turn the modules into packages.
 
 First we make a project directory for our new package. Usually the
 name of the project directory is the same as the one of the
-package. Here, however, we call the proejct directory `packagehowto`
+package. Here, however, we call the project directory `packagehowto`
 and the name of the package `numerix`.
 
 A package is a directory, and the name of the package is the name of
@@ -57,7 +58,9 @@ What makes this directory a package is the presence of a file named
 `__init__.py`. This file is executed when the package is imported. For
 now we leave it empty.
 
-The package directory resides in the `src/` directory of the project:
+The package directory resides in the `src/` directory of the
+project. The layout of your package project then looks like this:
+
 ```txt
 packagehowto/
 ├── pyproject.toml
@@ -100,7 +103,8 @@ is imported.
 You would need to reinstall the package whenever you change your
 package, for exmple when you add a new function or when you just fix
 some package code. This is tedious, and that is why there is a `-e`
-option for `pip install`. So install your package with
+option ("editable install") for `pip install`. So install your package
+with
 ```sh
 pip3 install -e .
 ```
@@ -112,8 +116,8 @@ without the need to reinstall the package again.
 
 This file is your package. In fact, you could write a package that
 only has an `__init__.py` file in the package directory. All code you
-want to make available in you package could be place in the
-`__init__.py` file. For example, if you define a `add_four()` function
+want to make available in you package could be placed in the
+`__init__.py` file. For example, if you define an `add_four()` function
 in `__init__.py` like this:
 ```
 def add_four(x):
@@ -131,8 +135,8 @@ it available directly from the package. With this line in `__init__.py`
 ```
 from .addition import add_two
 ```
-(note the `.` in front of `addition`!) you can import `add_two()`
-without specifying the module:
+(note the `.` in front of `addition` - this makes it a relative
+import) you can import `add_two()` without specifying the module:
 ```
 from numerix import add_two
 ```
@@ -164,6 +168,9 @@ Note, that the `numbers.py` module imports a function from the
 `addition.py` module via a relative import with the `.` in front of
 `addition`.
 
+And of course you can also import this function in `__init__.py` so
+that it can be imported from the package directly.
+
 
 ## Distribute your package
 
@@ -173,7 +180,7 @@ README.md
 
 LICENSE
 
-pypi.org
+[PyPi](https://pypi.org/)
 
 ```sh
 python3 -m build
@@ -188,6 +195,66 @@ token
 
 ## Package version
 
+For uploading your package to [PyPi](https://pypi.org/) you need to
+specify a version number in the `pyproject.toml` file. However, your
+package should also provide a `__version__` variable. And some
+scripts of your package might want to know about the version number
+as well when you call them with a `--version' argument.
+
+For the latter two cases, you can define a `__version__` variable in
+one of the modules, or even in a dedicated module, that you then
+import whereever you need it. Even better is to define it in the
+`__init__.py` file:
+
+```
+__version__ = '1.4.2'
+""" Current version of the numerix package as string 'x.y.z'. """
+
+__year__ = '2024'
+""" Year of the current numerix version as string. """
+```
+
+Then a script can easily check the package's version like this:
+
+```
+from numerix import __version__
+
+print(__version__)
+```
+
+Other modules of the package need to import it from the `__init__.py`
+file by a relative import to be able to use it:
+
+```
+from .__init__ import __version__
+
+
+def about():
+    print(f'{__name__} {__version__}')
+```
+
+But how do you get the very same version into the `pyproject.toml`
+file? It would be a very bad idea to write it there directly and
+update it whenever you change it in the `__init__.py` file.
+
+For this you need to specify the `version` field as `dynamic` in the
+`[project]` section. This tells the package tool that the version will
+be set dynamically by some code. There are several options to do
+so. The simplest one is to add a `[tool.setuptools.dynamic]` section
+where the version is read as an attribute from the `numerix` package,
+that is its `__init__.py`file:
+
+```txt
+...
+
+[project]
+name = "numerix"
+dynamic = ["version"]
+...
+
+[tool.setuptools.dynamic]
+version = {attr = "numerix.__version__"}
+```
 
 ## Unit tests
 

pyproject.toml

@@ -43,7 +43,7 @@ Documentation = "https://whale.am28.uni-tuebingen.de/git/benda/packagehowto/src/
 #numerix   = "numerix.numerix:main"
 
 [tool.setuptools.dynamic]
-version = {attr = "numerix.version.__version__"}
+version = {attr = "numerix.__version__"}
 
 #[tool.pytest.ini_options]
 #pythonpath = "src"

src/numerix/__init__.py

@@ -4,6 +4,19 @@
 Fancy numerics made easy.
 """
 
+
+__version__ = '1.4.2'
+""" Current version of the numerix package as string 'x.y.z'. """
+
+__year__ = '2024'
+""" Year of the current numerix version as string. """
+
+# Add them to documentation:
+__pdoc__ = {}
+__pdoc__['__version__'] = True
+__pdoc__['__year__'] = True
+
+
 # Functions defined directly in __init__.py can be imported directly
 # from the package (e.g. from numerix import add_four):
 def add_four(x):
@@ -25,4 +38,3 @@ def add_four(x):
 # Functions from the modules of the package can be imported into the
 # namespace of the package:
 from .addition import add_two
-from .version import __version__

src/numerix/addition.py

@@ -1,6 +1,2 @@
 def add_two(x):
     return x + 2
-
-
-
-

src/numerix/numbers.py

@@ -1,5 +1,11 @@
+from .__init__ import __version__
 from .addition import add_two
 
+
 def three():
     return add_two(1)
 
+
+def about():
+    print(f'{__name__} {__version__}')
+

src/numerix/version.py

@@ -1,14 +0,0 @@
-""" Version and year of the numerix package.
-"""
-
-__version__ = '1.4.2'
-""" Current version of the numerix package as string 'x.y.z'. """
-
-__year__ = '2024'
-""" Year of the current numerix version as string. """
-
-# Add them to documentation:
-__pdoc__ = {}
-__pdoc__['__version__'] = True
-__pdoc__['__year__'] = True
-