36 lines
2.3 KiB
Plaintext
36 lines
2.3 KiB
Plaintext
thunk
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/thuhnk/ , n. 1. [obs.] A piece of coding which provides an address: ,
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according to P. Z. Ingerman, who invented thunks in 1961 as a way of binding
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actual parameters to their formal definitions in Algol-60 procedure calls.
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If a procedure is called with an expression in the place of a formal
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parameter, the compiler generates a thunk which computes the expression and
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leaves the address of the result in some standard location. 2. Later
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generalized into: an expression, frozen together with its environment, for
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later evaluation if and when needed (similar to what in techspeak is called
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a closure ). The process of unfreezing these thunks is called forcing. 3. A
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stubroutine , in an overlay programming environment, that loads and jumps to
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the correct overlay. Compare trampoline. 4. Microsoft and IBM have both
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defined, in their Intel-based systems, a 16-bit environment (with
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bletcherous segment registers and 64K address limits) and a 32-bit
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environment (with flat addressing and semi-real memory management). The two
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environments can both be running on the same computer and OS (thanks to what
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is called, in the Microsoft world, WOW which stands for Windows On Windows).
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MS and IBM have both decided that the process of getting from 16- to 32-bit
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and vice versa is called a thunk ; for Windows 95, there is even a tool
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THUNK.EXE called a thunk compiler. 5. A person or activity scheduled in a
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thunklike manner. It occurred to me the other day that I am rather
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accurately modeled by a thunk I frequently need to be forced to completion.:
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paraphrased from a plan file. Historical note: There are a couple of
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onomatopoeic myths circulating about the origin of this term. The most
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common is that it is the sound made by data hitting the stack; another holds
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that the sound is that of the data hitting an accumulator. Yet another
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suggests that it is the sound of the expression being unfrozen at
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argument-evaluation time. In fact, according to the inventors, it was coined
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after they realized (in the wee hours after hours of discussion) that the
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type of an argument in Algol-60 could be figured out in advance with a
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little compile-time thought, simplifying the evaluation machinery. In other
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words, it had already been thought of ; thus it was christened a thunk ,
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which is the past tense of think at two in the morning.
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