satya - 3/9/2024, 11:53:57 AM

These are now called type hints

These are now called type hints

satya - 3/9/2024, 11:54:05 AM

Type hints and python

Type hints and python

Search for: Type hints and python

satya - 3/9/2024, 11:54:48 AM

Setting up vscode for typing

satya - 3/9/2024, 11:57:04 AM

Between strict and basic

satya - 3/9/2024, 12:10:35 PM

Here is how the settings file entry for strict typing based on a project (not workspace)

# in file 
# project/.vscode/settings.json
{
    "python.analysis.typeCheckingMode": "strict"
}

satya - 3/9/2024, 12:12:14 PM

Sometimes pylance grows crazy over types

satya - 3/9/2024, 12:13:50 PM

An example

def _getFlattenedDictionary(tomlConfigFilename: str) -> dict[str, Any]:
    # Read and parse the toml file
    toml_str = fileutils.read_text_file(tomlConfigFilename)
    parsed_toml: tomlkit.TOMLDocument = tomlkit.parse(toml_str)
    # convert it to json
    json_str: str = json.dumps(parsed_toml,indent=4)
    dict = json.loads(json_str)
    new_dict = _process_dict_for_aliases(dict)


    flat_dict = flatten(new_dict, reducer="dot") #type:ignore
    return flat_dict #type:ignore

satya - 3/9/2024, 12:14:34 PM

In brief: #type:ignore

your line #type:ignore

satya - 3/9/2024, 12:38:13 PM

Some type hints and initialization

# All imports needed for the type hints
from typing import Optional, Union

# Type hint for a list of integers
numbers: list[int] = [1, 2, 3]

# Type hint for a dictionary with string keys and float values
prices: dict[str, float] = {'apple': 0.99, 'banana': 0.59}

# Type hint for a set of strings
fruits: set[str] = {'apple', 'banana', 'cherry'}

satya - 3/9/2024, 12:39:21 PM

Nested collections

# Type hint for a list of dictionaries, 
# each with string keys and integer values

scores: list[dict[str, int]] = 
  [{'math': 90, 'science': 85}, {'math': 92, 'science': 88}]

# Type hint for a dictionary with string keys 
# and lists of floats as values

student_grades: dict[str, list[float]] = 
  {'Alice': [88.5, 92.3, 85.0], 'Bob': [72.5, 81.0, 78.9]}

satya - 3/9/2024, 12:40:39 PM

Some necessary imports

# This is still the case in new python
from typing import Optional, Union

satya - 3/9/2024, 12:40:53 PM

Using them

# Type hint for an optional string (can be a string or None)
optional_name: Optional[str] = None

# Type hint for a variable that can be either an int or a string
mixed_type: Union[int, str] = 42
mixed_type = "forty-two"

satya - 3/9/2024, 12:41:41 PM

Complex examples

# Type hint for a complex nested structure:
# A list of dictionaries with:
# - string keys
# - values that are either a list of integers or a single string

complex_structure: 
   list[dict[str, Union[list[int], str]]] = 

[
    {'numbers': [1, 2, 3], 'name': 'first'},
    {'numbers': [4, 5, 6], 'name': 'second'}
]

satya - 3/9/2024, 11:10:26 PM

Type: The special key word from typing

from typing import Any, Type

var1 = Type[Any]

satya - 3/9/2024, 11:12:10 PM

Observations