Originally, I intended to analyze django webpack; however, midway through, for the sake of rigorous documentation, I found myself having to delve into django components. Within django components, I discovered some mechanisms previously unknown to me. Consequently, let’s first discuss the typing issues encountered!
While recently reading the code of django components, I came across the following snippet in component_registry.py:
from typing import TYPE_CHECKING, Callable, Dict, Type, TypeVar
if TYPE_CHECKING:
from django_components import component
_TC = TypeVar("_TC", bound=Type["component.Component"])
From this, several points of knowledge can be gleaned:
- The
TYPE_CHECKINGvariable is used as a tag for handling type-related code by programmers. During actual execution, the internal code is not executed. More details can be found in the official typing documentation. TypeVarcan be used like this:
S = TypeVar('S', bound=str) # Can be any subtype of str
In this snippet, _TC signifies that it can be any subtype of component.Component.
Conclusion
Python is gradually enriching its type system, and many new usages are also emerging. However, compared to TypeScript, its type system is somewhat more advanced. Keep learning!
Additional aside: It’s quite strange that a
Componentis actually a django view.