Example Usage
Below, we'll show you how to display the keywords from each source, how to bypass using the threshold decorator entirely, then walk through examples that build on each other to show how arguments are overwritten.
Tracing
We added the ability to trace the source of each keyword argument. We set this using threshold's kwarg trace_level. trace_level uses the loguru package for logging and accepts the following arguments (case insenitive):
"critical""warning""success""info""debug"
We will see how this is used by trying out different log levels in the next set of examples.
Developer-Provided Arguments (Highest Level)
If you need to debug something really quickly and don't want to fuss around with files or CLI, you can pass the values in as keywords. This bypasses any external values provided from files, environment variables, or the CLI.
# main.py
from argmerge import threshold
@threshold(trace_level="DEBUG")
def main(first, second, third: float = 3.0, fourth: float = 4.0, fifth: int = 5):
print(
f"{first=}",
f"{second=}",
f"{third=}",
f"{fourth=}",
f"{fifth=}",
sep="\n",
)
if __name__ == "__main__":
main(first=1, second="second")
Outputs a list of keyword arguments with their sources listed in ascending priority order
$ uv run main.py
2025-10-15 21:08:02.681 | DEBUG | argmerge.trace:_write_trace:51 -
Parameter Name | Source
=======================================
third | Python Function Default
fourth | Python Function Default
fifth | Python Function Default
first | Developer-provided
second | Developer-provided
=======================================
first=1
second='second'
third=3.0
fourth=4.0
fifth=5
Default Function Values (Lowest Level)
# main.py
from argmerge import threshold
@threshold(trace_level="DEBUG")
def main(
first: int = 1,
second: str = "second",
third: float = 3.0,
fourth: float = 4.0,
fifth: int = 5,
):
print(
f"{first=}",
f"{second=}",
f"{third=}",
f"{fourth=}",
f"{fifth=}",
sep="\n",
)
if __name__ == "__main__":
main()
Output
$ uv run main.py
2025-10-15 21:19:07.874 | DEBUG | argmerge.trace:_write_trace:51 -
Parameter Name | Source
=======================================
first | Python Function Default
second | Python Function Default
third | Python Function Default
fourth | Python Function Default
fifth | Python Function Default
=======================================
first=1
second='second'
third=3.0
fourth=4.0
fifth=5
JSON (Second Lowest)
JSON Config
// threshold.json
{
"first": 100,
"second": "Python"
}
# main.py
from argmerge import threshold
@threshold(fpath_json="threshold.json", trace_level="DEBUG")
def main(
first: int,
second: str,
third: float = 3.0,
fourth: float = 4.0,
fifth: int = 5,
):
print(
f"{first=}",
f"{second=}",
f"{third=}",
f"{fourth=}",
f"{fifth=}",
sep="\n",
)
if __name__ == "__main__":
main()
Outputs
$ uv run main.py
2025-10-15 21:19:36.388 | DEBUG | argmerge.trace:_write_trace:51 -
Parameter Name | Source
=======================================
third | Python Function Default
fourth | Python Function Default
fifth | Python Function Default
first | JSON (threshold.json)
second | JSON (threshold.json)
=======================================
first=100
second='Python'
third=3.0
fourth=4.0
fifth=5
YAML (Third Lowest)
# threshold.yaml
third: -3.333
# main.py
from argmerge import threshold
@threshold(
fpath_json="threshold.json",
fpath_yaml="threshold.yaml",
trace_level="DEBUG"
)
def main(
first: int,
second: str,
third: float = 3.0,
fourth: float = 4.0,
fifth: int = 5,
):
print(
f"{first=}",
f"{second=}",
f"{third=}",
f"{fourth=}",
f"{fifth=}",
sep="\n",
)
if __name__ == "__main__":
main()
Output
$ uv run main.py
2025-10-15 21:24:21.619 | DEBUG | argmerge.trace:_write_trace:51 -
Parameter Name | Source
=======================================
fourth | Python Function Default
fifth | Python Function Default
first | JSON (threshold.json)
second | JSON (threshold.json)
third | YAML (threshold.yaml)
=======================================
first=100
second='Python'
third=-3.333
fourth=4.0
fifth=5
Environment Variables (Third Highest)
$ export EXAMPLE_THRESH_FOURTH=-14.0
# main.py
from argmerge import threshold
@threshold(
fpath_json="threshold.json",
fpath_yaml="threshold.yaml",
env_prefix="EXAMPLE_THRESH",
trace_level="WARNING",
)
def main(
first: int,
second: str,
third: float = 3.0,
fourth: float = 4.0,
fifth: int = 5,
):
print(
f"{first=}",
f"{second=}",
f"{third=}",
f"{fourth=}",
f"{fifth=}",
sep="\n",
)
if __name__ == "__main__":
main()
Outputs
$ uv run main.py
2025-10-15 21:26:37.188 | DEBUG | argmerge.trace:_write_trace:51 -
Parameter Name | Source
=======================================
fifth | Python Function Default
first | JSON (threshold.json)
second | JSON (threshold.json)
third | YAML (threshold.yaml)
fourth | Environment Variable
=======================================
first=100
second='Python'
third=-3.333
fourth=-14.0
fifth=5
Command-Line Arguments (Second Highest)
# main.py
from argmerge import threshold
@threshold(
fpath_json="threshold.json",
fpath_yaml="threshold.yaml",
env_prefix="EXAMPLE_THRESH",
cli_pattern=r"--([A-Za-z_-]+)=([0-9A-Za-z._-]+)", # the default pattern
trace_level="WARNING",
)
def main(
first: int,
second: str,
third: float = 3.0,
fourth: float = 4.0,
fifth: int = 5,
):
print(
f"{first=}",
f"{second=}",
f"{third=}",
f"{fourth=}",
f"{fifth=}",
sep="\n",
)
if __name__ == "__main__":
main()
Output
$ uv run main.py -- --fifth=3.14
$ # you can also run
$ # python main.py --fifth=3.14
2025-10-15 21:28:51.405 | DEBUG | argmerge.trace:_write_trace:51 -
Parameter Name | Source
=====================================
first | JSON (threshold.json)
second | JSON (threshold.json)
third | YAML (threshold.yaml)
fourth | Environment Variable
fifth | CLI
=====================================
first=100
second='Python'
third=-3.333
fourth=-14.0
fifth='3.14'