System function

Function

system function is the global basic capability of BT runtime, covering environment introspection, dynamic calling, type conversion, JSON serialization, regularization, path, sleep, random number and standard library construction entry.

API list

API	Description
envs	Read system environment objects, or read system functions, standard library constructors, and system constants by name.
env	Read the user global environment object, or read the user global variable by name.
has_envs	Determine whether the specified name exists in the system environment.
has_env	Determine whether the specified variable exists in the user's global environment.
pause	Output an optional prompt to the console and wait for the user to press Enter.
assert	Assert that the condition is true and throw a runtime error when it fails.
echo	Convert all parameters into strings, connect them with spaces and output them to the console.
bool	Convert the value to a Boolean value according to BT truth rules.
eval	Compile and execute a string script, returning the value of the script's explicit return or exit.
exit	Set the exit value and end the current script execution.
include	Introduce and execute the BT file during runtime, and return the value of the explicit return or exit of the imported file.
include_once	BT files are introduced and executed during runtime. The same real file in the same execution context is only executed once.
cur_dir	Return to the directory where the current source code file is located.
cur_file	Return the current source code file path.
cur_root	Returns the current VM project root directory.
type	The script-visible type name of the return value.
call	Dynamically call a function by function name or function value.
task	Create a lightweight background task and read the status and results through await, done, result, on_done.
task_all	Wait for a set of Tasks to be completed and return an array of successful results in the order of input.
task_race	Wait for the first completed task in a set of Tasks and return its result.
set_timeout	Register a one-time delay callback and return the Timer object immediately.
set_interval	Register a fixed-delay repeating callback and return a Timer object immediately.
Timer.cancel	Cancel a timeout or subsequent interval that has not yet been triggered.
number	Convert the value to a number.
string	Convert the value to a string.
float	Convert a value to a floating point number.
int	Convert the value to an integer.
array	Convert a value to an array.
object	Convert a value to an object.
json	Serializes a value into a standard JSON string.
regex	Compiles a regular expression and returns a Regex object.
is_empty	Determine whether the value is empty.
is_null	Determine whether the value is Null.
sleep	Let the current thread sleep for the specified number of milliseconds.
rand	Generate pseudo-random numbers.

Examples

Notes

System functions are stateless; object standard library entries such as fs, html, crypto, url, path, bytes, mysql, modbus, reqwest are created by the library construction branch of the VM.

- print and println are language output statements and are not system functions dynamically callable through call(); their usage is described in Output .

echo is a system function that supports echo(value) and single-argument parentheses-free syntax.