Tektronix Keithley 2651A Reference Manual page 304

Model 2651A High Power System SourceMeter® Instrument Reference Manual
Base library functions
Base library functions
Function
collectgarbage()
collectgarbage(limit)
gcinfo()
tonumber(x)
tonumber(x, base)
tostring(x)
type(v)
Lua memory management
Lua automatically manages memory, which means you do not have to allocate memory for new
objects and free it when the objects are no longer needed. Lua occasionally runs a garbage collector
to collect all objects that are no longer accessible from Lua. All objects in Lua are subject to automatic
management, including tables, variables, functions, threads, and strings.
Lua uses two numbers to control its garbage-collection cycles. One number counts how many bytes
of dynamic memory Lua is using; the other is a threshold. When the number of bytes crosses the
threshold, Lua runs the garbage collector, which reclaims the memory of all inaccessible objects. The
byte counter is adjusted, and the threshold is reset to twice the new value of the byte counter.
2651A-901-01 Rev. C October 2021
Description
Sets the garbage-collection threshold to the given limit (in kilobytes) and
checks it against the byte counter. If the new threshold is smaller than the
byte counter, Lua immediately runs the garbage collector. If there is no limit
parameter, it defaults to zero (0), which forces a garbage-collection cycle.
See Lua memory management
Returns the number of kilobytes of dynamic memory that the Test Script
®
Processor (TSP ) scripting engine is using and returns the present
garbage collector threshold (also in kilobytes). See
management (on page 6-31) for more information.
Returns x converted to a number. If x is already a number, or a convertible
string, the number is returned; otherwise, it returns nil.
An optional argument specifies the base to use when interpreting the
numeral. The base may be any integer from 2 to 36, inclusive. In bases
above 10, the letter A (in either upper or lower case) represents 10, B
represents 11, and so forth, with Z representing 35. In base 10, the default,
the number may have a decimal part and an optional exponent. In other
bases, only unsigned integers are accepted.
Receives an argument of any type and converts it to a string in a
reasonable format.
Returns (as a string) the type of its only argument. The possible results of
this function are "nil" (a string, not the value nil), "number",
"string", "boolean", "table", "function", "thread",
and "userdata".
Section 6: Instrument programming
(on page 6-31) for more information.
Lua memory
6-31