build: make dependency on Click optional

CHANGELOG.rst

@@ -11,12 +11,27 @@ The format is based on `Keep a Changelog`_, and this project adheres to
 `0.3.0`_ - 2024-05-15
 ---------------------
 
+Incompatible
+~~~~~~~~~~~~
+
+- The `shamir` command no longer works out of the box. It is necessary to install the
+  `cli` extra while installing the package. See README for instructions.
+
 Added
 ~~~~~
 
 - Added BIP32 master extended private key to test vectors.
 - Added support for extendable backup flag.
 
+Changed
+~~~~~~~
+
+- The `shamir_mnemonic` package now has zero extra dependencies on Python 3.7 and up,
+  making it more suitable as a dependency of other projects.
+- The `shamir` CLI still requires `click`. A new extra `cli` was introduced to handle
+  this dependency. Use the command `pip install shamir-mnemonic[cli]` to install the CLI
+  dependencies along with the package.
+
 Removed
 ~~~~~~~
 

README.rst

@@ -35,11 +35,11 @@ not be used for handling sensitive secrets**.
 Installation
 ------------
 
-With pip from GitHub:
+With pip from PyPI:
 
 .. code-block:: console
 
-    $ pip3 install shamir-mnemonic
+    $ pip3 install shamir-mnemonic[cli]  # for CLI tool
 
 From local checkout for development:
 

pyproject.toml

@@ -11,15 +11,18 @@ readme = [
 
 [tool.poetry.dependencies]
 python = ">=3.6,<4.0"
-click = ">=7,<9"
 dataclasses = { version = "*", python = "<=3.6" }
+click = { version = ">=7,<9", optional = true }
 
 [tool.poetry.group.dev.dependencies]
 bip32utils = "^0.3.post4"
 pytest = "*"
 black = ">=20"
 isort = "^5"
 
+[tool.poetry.extras]
+cli = ["click"]
+
 [tool.poetry.scripts]
 shamir = "shamir_mnemonic.cli:cli"
 

shamir_mnemonic/cli.py

@@ -2,8 +2,14 @@
 import sys
 from typing import Sequence, Tuple
 
-import click
-from click import style
+try:
+    import click
+    from click import style
+
+except ImportError:
+    print("Required dependencies are missing. Install them with:")
+    print("  pip install shamir_mnemonic[cli]")
+    sys.exit(1)
 
 from .recovery import RecoveryState
 from .shamir import generate_mnemonics