<programming> /thuhnk/ 1. "A piece of coding which provides an
address", according to P. Z. Ingerman, who invented thunks in
1961 as a way of binding actual parameters to their formal
definitions in ALGOL 60 procedure calls. If a procedure
is called with an expression in the place of a formal
parameter, the compiler generates a thunk which computes the
expression and leaves the address of the result in some
standard location.
2. The term was later generalised to mean an expression,
frozen together with its environment (variable values), for
later evaluation if and when needed (similar to a
"closure"). The process of unfreezing these thunks is
called "forcing".
3. A stubroutine, in an overlay programming environment,
that loads and jumps to the correct overlay.
Compare trampoline.
There are a couple of onomatopoeic myths circulating about the
origin of this term. The most common is that it is the sound
made by data hitting the stack; another holds that the sound
is that of the data hitting an accumulator. Yet another
suggests that it is the sound of the expression being unfrozen
at argument-evaluation time. In fact, according to the
inventors, it was coined after they realised (in the wee hours
after hours of discussion) that the type of an argument in
ALGOL 60 could be figured out in advance with a little
compile-time thought, simplifying the evaluation machinery.
In other words, it had "already been thought of"; thus it was
christened a "thunk", which is "the past tense of "think" at
two in the morning".
4. (Microsoft Windows programming) universal thunk,
generic thunk, flat thunk.
[Jargon File]
(1997-10-11)
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