Warnings

wybthon._warnings¶

_warnings ¶

Development-mode warnings and error reporting.

A process-wide DEV_MODE flag and helpers that surface clear, actionable messages during development while keeping production builds quiet. All output goes to sys.stderr.

Dev-mode diagnostics raised elsewhere in the framework:

Top-level reactive read: a signal, memo, or prop was called at the top level of a component body, where the read isn't tracked.
Write in tracking scope: a signal was written inside a memo, a single-function effect, or a reactive hole (WriteInScopeError).
Static list in For: For received a plain list instead of an accessor, so it will only render once.

Functions:

Name	Description
`set_dev_mode`	Enable or disable development mode diagnostics globally.
`is_dev_mode`	Return whether development mode is currently active.
`warn`	Print a development-mode warning to `stderr` (no-op when dev mode is off).
`warn_once`	Print `message` at most once per `(category, key)` pair.
`log_error`	Log an error to `stderr`, with a traceback in dev mode.
`component_name`	Return a human-readable display name for a component or tag.
`warn_each_plain_list`	Warn that `For` received a static list.

DEV_MODE `module-attribute` ¶

DEV_MODE: bool = True

Process-wide flag toggling Wybthon's development diagnostics.

Defaults to True. Production builds should call set_dev_mode(False) at startup.

set_dev_mode ¶

set_dev_mode(enabled: bool) -> None

Enable or disable development mode diagnostics globally.

Parameters:

Name	Type	Description	Default
`enabled`	`bool`	When `False`, `warn` and `warn_once` become no-ops, `WriteInScopeError` is not raised, and tracebacks are suppressed in `log_error`.	required

is_dev_mode ¶

is_dev_mode() -> bool

Return whether development mode is currently active.

warn ¶

warn(message: str) -> None

Print a development-mode warning to stderr (no-op when dev mode is off).

warn_once ¶

warn_once(category: str, key: Any, message: str) -> None

Print message at most once per (category, key) pair.

log_error ¶

log_error(message: str, error: BaseException | None = None) -> None

Log an error to stderr, with a traceback in dev mode.

Always logs regardless of DEV_MODE, since errors indicate real problems.

component_name ¶

component_name(comp: Any) -> str

Return a human-readable display name for a component or tag.

warn_each_plain_list ¶

warn_each_plain_list(component: Any) -> None

Warn that For received a static list.

What's in this module¶

_warnings is Wybthon's lightweight development-mode diagnostics layer. It gives the framework a single place to surface actionable warnings and error tracebacks while developing. Warning output and exception tracebacks can be disabled for production; error messages still go to stderr.

Three things live here:

Dev-mode toggling: dev mode is on by default, and wyb dev keeps it on. Production builds (wyb build) record the mode in the bundle manifest, and the bootstrap calls set_dev_mode(False) before the application imports, so production apps skip the dev-only checks and warnings. Call it yourself when you mount outside the production bootstrap. Turning dev mode off also disables WriteInScopeError for signal and store writes inside tracking scopes, the run-time TypeError for unknown or missing component props, and the TemplateError for a template that wasn't compiled. is_dev_mode() reports the live state. Both functions are re-exported from the top-level wybthon package; the module-level DEV_MODE flag is internal, and wybthon.DEV_MODE no longer exists.
Warnings: warn prints a message to stderr every time it's called (a no-op when dev mode is off), while warn_once deduplicates by a (category, key) pair so repeated calls with the same pair only log once per process. The reactive system uses this path for untracked reads of signals, memos, and props at the top level of a component body. warn_each_plain_list also uses it when For receives a static list or tuple.
Error logging: log_error always prints, regardless of dev mode; in dev mode it also prints the full traceback of an attached exception.

component_name is a small formatting helper shared by the warning functions above to produce a readable name for a tag string, a function component, or a class instance in warning text.

Application code doesn't usually call into _warnings directly beyond set_dev_mode/is_dev_mode. The other helpers are used internally by the reactive system and flow-control primitives to flag common reactivity mistakes early.