[squeak-dev] Pragmas (Re: The Inbox: Morphic-phite.429.mcz)
Andreas Raab
andreas.raab at gmx.de
Mon Apr 26 19:05:41 UTC 2010
On 4/26/2010 11:48 AM, Eliot Miranda wrote:
> OK, so Pragma is bad; its historical from "primitive pragma". But
> Annotation doesn't capture the potentially executable flavour of
> pragmas. How about MethodMetaMessage? (mmm, yum :) ) We could talk
> about meta-messages for short. "Add a meta-message that does ..." etc...
But "primitive pragma" is every bit as wrong. A pragma is something that
gives the compiler information about the code without being code itself.
Primitives are't pragmas, primitives are *code* (if you don't believe
me, just remove all of them and see how that goes).
By definition, a "pragma" is an interface between the code and the
compiler, something where the code conveys meta-information to the
compiler. For example, this is a pragma (assuming the compiler
understands it):
foo
<inline: true>
bar
<tailcut: true>
The first one might instruct the compiler to generate the code for this
method inline, the second one to eliminate tail recursion.
None of these, however, are pragmas:
foo
"Not a pragma since it's not for the compiler"
<preference: 'Foo Preference'
...
>
apiGetWindowFocus
"Not a pragma since it's code"
<apicall: ulong 'GetWindowFocus' (void)>
etc. I should also add that before the introduction of the so-called
"pragmas" there was only *code* used in the <> syntax (primitives and
FFI calls) and the change to allow non-code entities is something that,
although useful, still worries me because of the conceptual issues
associated with mixing code and non-code entities. We wouldn't even have
that discussion if <> just meant "code".
Cheers,
- Andreas
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