Add Specify Parameter Name For Click Option as a Python TIL

README.md

@@ -10,7 +10,7 @@ working across different projects via [VisualMode](https://www.visualmode.dev/).
 
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-_1871 TILs and counting..._
+_1872 TILs and counting..._
 
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@@ -1131,6 +1131,7 @@ If you've learned something here, support my efforts writing daily TILs by
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 - [Sort A List Of Dataclass Instances](python/sort-a-list-of-dataclass-instances.md)
 - [Sort Normalized Version Of Data](python/sort-normalized-version-of-data.md)
+- [Specify Parameter Name For Click Option](python/specify-parameter-name-for-click-option.md)
 - [Start Jupyter Notebook With Extra Packages](python/start-jupyter-notebook-with-extra-packages.md)
 - [Start The Debugger When A Test Errors](python/start-the-debugger-when-a-test-errors.md)
 - [Store And Access Immutable Data In A Tuple](python/store-and-access-immutable-data-in-a-tuple.md)

python/specify-parameter-name-for-click-option.md

@@ -0,0 +1,55 @@
+# Specify Parameter Name For Click Option
+
+[Click](https://click.palletsprojects.com/en/stable/)'s option decorator
+provides a versatile way to define flags for a command. It has good defaults
+that minimize the aspects of a flag that I need to be explicit about.
+
+For example, a boolean `--init` flag for the `config` command could be specified
+like so:
+
+```python
+@cli.command()
+@click.option(
+    "--init",
+    help="Initialize a config file with minimal defaults",
+    is_flag=True,
+)
+@pass_cli
+def config(cli_ctx: CliContext, init: bool):
+    # ...
+```
+
+Notice, in particular, that the flag string (`--init`) that I pass as the first
+argument to `@click.option` has to correspond to the name of the parameter
+`init`. Click passes all the defined options as keyword arguments when invoking
+`config`. If the `init` parameter was changed to `initial`, there would be a
+runtime error like this: `TypeError: config() got an unexpected keyword argument 'init'`.
+
+Like I said though, Click is flexible when I need it to be. I can leave the flag
+name as it is, but specify a different name to be used for the function
+parameter. I found this useful when I realized that as I added support for a
+`--json` flag I was inadvertently superseding the `json` import.
+
+The second positional argument to `@click.option` can be included to rename that
+parameter:
+
+```python
+import json
+
+
+@cli.command()
+@click.option(
+    "--json",
+    "use_json",
+    help="Output all info details in JSON format",
+    is_flag=True,
+)
+@pass_cli
+def info(cli_ctx: CliContext, use_json: bool):
+    # ...
+
+    if use_json:
+        click.echo(json.dumps(info_details, indent=2))
+```
+
+Both of these code blocks are excerpts from my [`py-vmt` time tracker project](https://github.com/jbranchaud/py-vmt).