Metadata-Version: 2.1
Name: argtyped
Version: 0.1
Summary: Command line arguments, with types
Home-page: https://github.com/huzecong/argtyped
Author: Zecong Hu
Author-email: huzecong@gmail.com
License: MIT License
Description: # `argtyped`: Command Line Argument Parser, with Types
        
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        `argtyped` is an command line argument parser with that relies on type annotations. It is built on
        [`argparse`](https://docs.python.org/3/library/argparse.html), the command line argument parser library built into
        Python. Compared with `argparse`, this library gives you:
        
        - More concise and intuitive syntax, less boilerplate code.
        - Type checking and IDE auto-completion for command line arguments.
        - A drop-in replacement for `argparse` in most cases.
        
        
        ## Installation
        
        Install stable release from [PyPI](https://pypi.org/project/argtyped/):
        ```bash
        pip install argtyped
        ```
        
        Or, install the latest commit from GitHub:
        ```bash
        pip install -e git+https://github.com/huzecong/argtyped.git
        ```
        
        ## Usage
        
        With `argtyped`, you can define command line arguments in a syntax similar to
        [`typing.NamedTuple`](https://docs.python.org/3/library/typing.html#typing.NamedTuple). The syntax is intuitive and can
        be illustrated with an example:
        ```python
        from typing import Optional
        
        from argtyped import Arguments, Choices, Switch
        from argtyped import Enum, auto
        
        class LoggingLevels(Enum):
            Debug = auto()
            Info = auto()
            Warning = auto()
            Error = auto()
            Critical = auto()
        
        class MyArguments(Arguments):
            model_name: str         # required argument of `str` type
            hidden_size: int = 512  # `int` argument with default value of 512
        
            activation: Choices['relu', 'tanh', 'sigmoid'] = 'relu'  # argument with limited choices
            logging_level: LoggingLevels = LoggingLevels.Info        # using `Enum` class as choices
        
            use_dropout: Switch = True  # switch argument, enable with "--use-dropout" and disable with "--no-use-dropout"
            dropout_prob: Optional[float] = 0.5  # optional argument, "--dropout-prob=none" parses into `None`
        
        args = Arguments()
        ```
        
        This is equivalent to the following code with Python built-in `argparse`:
        ```python
        import argparse
        from enum import Enum
        
        class LoggingLevels(Enum):
            Debug = "debug"
            Info = "info"
            Warning = "warning"
            Error = "error"
            Critical = "critical"
        
        parser = argparse.ArgumentParser()
        
        parser.add_argument("--model-name", type=str, required=True)
        parser.add_argument("--hidden-size", type=int, default=512)
        
        parser.add_argument("--activation", choices=["relu", "tanh", "sigmoid"], default="relu")
        parser.add_argument("--logging-level", choices=list(LoggingLevels), type=LoggingLevels, default="info")
        
        parser.add_argument("--use-dropout", action="store_true", dest="use_dropout", default=True)
        parser.add_argument("--no-use-dropout", action="store_false", dest="use_dropout")
        parser.add_argument("--dropout-prob", type=lambda s: None if s.lower() == 'none' else float(s), default=0.5)
        
        args = parser.parse_args()
        ```
        
        Save the code into a file named `main.py`. Suppose the following arguments are provided:
        ```bash
        python main.py \
            --model-name LSTM \
            --activation sigmoid \
            --logging-level debug \
            --no-use-dropout \
            --dropout-prob none
        ```
        Then the parsed arguments will be equivalent to the following structured returned by `argparse`:
        ```python
        argparse.Namespace(
            model_name="LSTM", hidden_size=512, activation="sigmoid", logging_level="debug",
            use_dropout=False, dropout_prob=None)
        ```
        
        Arguments can also be pretty-printed with `print(args.to_string())`, which gives:
        ```
        <class '__main__.MyArguments'>
        ╔═════════════════╤══════════════════════════════════╗
        ║ Arguments       │ Values                           ║
        ╠═════════════════╪══════════════════════════════════╣
        ║ model_name      │ 'LSTM'                           ║
        ║ hidden_size     │ 512                              ║
        ║ activation      │ 'sigmoid'                        ║
        ║ logging_level   │ <MyLoggingLevels.Debug: 'debug'> ║
        ║ use_dropout     │ False                            ║
        ║ dropout_prob    │ None                             ║
        ║ label_smoothing │ 0.1                              ║
        ║ some_true_arg   │ True                             ║
        ║ some_false_arg  │ False                            ║
        ╚═════════════════╧══════════════════════════════════╝
        ```
        
        ## Reference
        
        ### The `argtyped.Arguments` Class
        
        The `argtyped.Arguments` class is main class of the package, from which you should derive your custom class that holds
        arguments. Each argument takes the form of a class attribute, with its type annotation and an optional default value.
        
        When an instance of your custom class is initialized, the command line arguments are parsed from `sys.argv` into values
        with your annotated types. You can also provide the list of strings to parse by passing them as the parameter.
        
        The parsed arguments are stored in an object of your custom type. This gives you arguments that can be auto-completed
        by the IDE, and type-checked by a static type checker like [`mypy`](http://mypy-lang.org/).
        
        The following example illustrates the keypoints:
        ```python
        class MyArgs(argtyped.Arguments):
            # name: type [= default_val]
            value: int = 0
        
        args = MyArgs()                    # equivalent to `parser.parse_args()`
        args = MyArgs(["--value", "123"])  # equivalent to `parser.parse_args(["--value", "123"])
        assert isinstance(args, MyArgs)
        ```
        
        ### Argument Types
        
        To summarize, whatever works for `argparse` works here. The following types are supported:
        
        - Built-in types such as `int`, `float`, `str`.
        - `bool` type. Accepted values (case-insensitive) for `True` are: `y`, `yes`, `true`, `ok`; accepted values for `False`
          are: `n`, `no`, `false`.
        - Choice types `Choices[...]`. A choice argument is essentially an `str` argument with limited choice of values. The
          ellipses can be filled with a tuple of `str`s, or an expression that evaluates to a list of `str`s:
          ```python
          from argtyped import Arguments, Choices
          from typing import List
        
          def logging_levels() -> List[str]:
              return ["debug", "info", "warning", "error"]
        
          class MyArgs(Arguments):
              foo: Choices["debug", "info", "warning", "error"]  # 4 choices
              bar: Choices[logging_levels()]                     # the same 4 choices
        
          # argv: ["--foo=debug", "--bar=info"] => foo="debug", bar="info"
          ```
          This is equivalent to the `choices` keyword in `argparse.add_argument`.
        - Enum types derived from `enum.Enum`. It is recommended to use `argtyped.Enum` which uses the instance names as values:
          ```python
          from argtyped import Enum
        
          class MyEnum(Enum):
              Debug = auto()    # "debug"
              Info = auto()     # "info"
              Warning = auto()  # "warning"
          ```
        - Switch types `Switch`. `Switch` arguments are like `bool` arguments, but they don't take values. Instead, a switch
          argument `switch` requires `--switch` to enable and `--no-switch` to disable:
          ```python
          from argtyped import Arguments, Switch
        
          class MyArgs(Arguments):
              switch: Switch = True
              bool_arg: bool = False
        
          # argv: []                                 => flag=True, bool_arg=False
          # argv: ["--switch", "--bool-arg=false"]   => flag=True, bool_arg=False
          # argv: ["--no-switch", "--bool-arg=true"] => flag=False, bool_arg=True
          # argv: ["--switch=false"]                 => WRONG
          # argv: ["--no-bool-arg"]                  => WRONG
          ```
        - Optional types `Optional[T]`, where `T` is any supported type (except choices or switch). An optional argument will be
          filled with `None` if no value is provided. It could also be explicitly set to `None` by using `none` as value in the
          command line:
          ```python
          from argtyped import Arguments
          from typing import Optional
        
          class MyArgs(Arguments):
              opt_arg: Optional[int]  # implicitly defaults to `None`
        
          # argv: []                 => opt_arg=None
          # argv: ["--opt-arg=1"]    => opt_arg=1
          # argv: ["--opt-arg=none"] => opt_arg=None
          ```
        - Any other type that takes a single `str` as `__init__` parameters. It is also theoretically possible to use a function
          that takes an `str` as input, but it's not recommended as it's not type-safe.
        
        
        ## Caveats
        
        - Advanced `argparse` features such as subparsers, groups, argument lists, and custom actions are not supported.
        - Using switch arguments may result in name clashes: if a switch argument has name `arg`, there can be no argument with
          the name `no_arg`.
        - `Optional` cannot be used with `Choices`. You can add `"none"` as a valid choice to mimic a similar behavior.
        - `Optional[str]` would parse a value of `"none"` into `None`.
        
        ## Under the Hood
        
        This is what happens under the hood:
        1. When an instance of `argtyped.Arguments` (or any subclass) is initialized, type annotations and class-level
           attributes (i.e., the default values) are collected to form argument declarations.
        2. After verifying the validity of declared arguments, an instance of `argparse.ArgumentParser` is created and arguments
           are registered with the parser.
        3. The parser's `parse_args` method is invoked with either `sys.argv` or strings provided as parameters, returning
           parsed arguments.
        4. The parsed arguments are assigned to `self` (the instance of `Arguments` subclass being initialized).
        
Platform: any
Classifier: Development Status :: 4 - Beta
Classifier: Environment :: Console
Classifier: Intended Audience :: Developers
Classifier: Intended Audience :: Science/Research
Classifier: Operating System :: OS Independent
Classifier: License :: OSI Approved :: MIT License
Classifier: Programming Language :: Python :: 3 :: Only
Classifier: Programming Language :: Python :: 3.6
Classifier: Programming Language :: Python :: 3.7
Classifier: Topic :: System :: Shells
Classifier: Topic :: Utilities
Classifier: Typing :: Typed
Requires-Python: >=3.6
Description-Content-Type: text/markdown
