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Amy de Buitléir 2023-12-03 20:02:39 +00:00
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source/new-flake/python-flake/main.adoc0
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@ -10,7 +10,7 @@ $ git init
== A simple Python program
Next, we’ll create a simple Python program.
Next, we'll create a simple Python program.
////
$ curl https://codeberg.org/mhwombat/hello-flake-python/raw/branch/main/hello.py --silent --output hello.py
@ -22,14 +22,14 @@ $ curl https://codeberg.org/mhwombat/hello-flake-python/raw/branch/main/hello.py
$# cat hello.py
....
Before we package the program, let’s verify that it runs. We’re going to
need Python. By now you’ve probably figured out that we can write a
`flake.nix` and define a development shell that includes Python. We’ll
Before we package the program, let's verify that it runs. We're going to
need Python. By now you've probably figured out that we can write a
`flake.nix` and define a development shell that includes Python. We'll
do that shortly, but first I want to show you a handy shortcut. We can
lauch a _temporary_ shell with any Nix packages we want. This is
convenient when you just want to try out some new software and you’re
not sure if you’ll use it again. It’s also convenient when you’re not
ready to write `flake.nix` (perhaps you’re not sure what tools and
launch a _temporary_ shell with any Nix packages we want. This is
convenient when you just want to try out some new software and you're
not sure if you'll use it again. It's also convenient when you're not
ready to write `flake.nix` (perhaps you're not sure what tools and
packages you need), and you want to experiment a bit first.
The command to enter a temporary shell is
@ -43,14 +43,14 @@ If there are multiple packages, they should be separated by spaces.
The command used here is `nix-shell` with a hyphen, not `nix shell`
with a space; those are two different commands. In fact there are
hyphenated and non-hyphenated versions of many Nix commands, and yes,
it’s confusing. The non-hyphenated commands were introduced when support
it's confusing. The non-hyphenated commands were introduced when support
for flakes was added to Nix. I predict that eventually all hyphenated
commands will be replaced with non-hyphenated versions. Until then, a
useful rule of thumb is that non-hyphenated commands are for for working
directly with flakes; hyphenated commands are for everything else.
====
Let’s enter a shell with Python so we can test the program.
Let's enter a shell with Python so we can test the program.
....
$# echo '$ nix-shell -p python3'
@ -60,7 +60,7 @@ $ python hello.py
== A Python builder
Next, create a Python script to build the package. We’ll use Python’s
Next, create a Python script to build the package. We'll use Python's
setuptools, but you can use other build tools. For more information on
setuptools, see the
https://packaging.python.org/en/latest/guides/distributing-packages-using-setuptools/[Python
@ -78,17 +78,17 @@ $ curl https://codeberg.org/mhwombat/hello-flake-python/raw/branch/main/setup.py
$# cat setup.py
....
We won’t write `flake.nix` just yet. First we’ll try building the
We won't write `flake.nix` just yet. First we'll try building the
package manually.
....
$ python -m build
....
The missing module error happens because we don’t have `build` available
The missing module error happens because we don't have `build` available
in the temporary shell. We can fix that by adding "`build`" to the
temporary shell. When you need support for both a language and some of
its packages, it’s best to use one of the Nix functions that are
its packages, it's best to use one of the Nix functions that are
specific to the programming language and build system. For Python, we
can use the `withPackages` function.
@ -97,7 +97,7 @@ $# echo '$ nix-shell -p "python3.withPackages (ps: with ps; [ build ])"'
$# nix-shell -p "python3.withPackages (ps: with ps; [ build ])" --command sh
....
Note that we’re now inside a temporary shell inside the previous
Note that we're now inside a temporary shell inside the previous
temporary shell! To get back to the original shell, we have to `exit`
twice. Alternatively, we could have done `exit` followed by the
`nix-shell` command.
@ -115,7 +115,7 @@ Now we should write `flake.nix`. We already know how to write most of
the flake from the examples we did earlier. The two parts that will be
different are the development shell and the package builder.
Let’s start with the development shell. It seems logical to write
Let's start with the development shell. It seems logical to write
something like the following.
....
@ -172,13 +172,13 @@ $ curl https://codeberg.org/mhwombat/hello-flake-python/raw/branch/main/flake.ni
$# cat flake.nix
....
Let’s try out the new flake.
Let's try out the new flake.
....
$ nix run
....
Why can’t it find `flake.nix`? Nix flakes only "`see`" files that are
Why can't it find `flake.nix`? Nix flakes only "`see`" files that are
part of the repository. We need to add all of the important files to the
repo before building or running the flake.
@ -187,7 +187,7 @@ $ git add flake.nix setup.py hello.py
$ nix run
....
We’d like to share this package with others, but first we should do some
We'd like to share this package with others, but first we should do some
cleanup. When the package was built (automatically by the `nix run`
command), it created a `flake.lock` file. We need to add this to the
repo, and commit all important files.