forked from alex-eg/sex
alex-eg
bf83baa508
'#+' and '#-' introduce conditional compilation: the form that follows is kept only when the feature expression is true, and otherwise is read and thrown away. An expression is a feature name, or and / or / not of them. They are read time, not compile time. Default features are the host's software-version, software-type and machine-type as CHICKEN reports them, plus what --features flag adds.
24 lines
673 B
Scheme
24 lines
673 B
Scheme
(compilation "--features=test-on")
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(input)
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(output "selected" "on" "and-not")
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(return 0)
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;;; #+ and #- pick what the compiler gets to see. `test-on' is handed
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;;; to sexc by the (compilation ...) form above, so this program reads
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;;; the same way on every platform.
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(include stdio.h)
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#+test-on (define GREETING "on")
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#-test-on (define GREETING "off")
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#-test-on (pub fn main () int (puts "the whole function is dropped") (return 1))
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(pub fn main () int
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;; ...and inside a form, not only at toplevel
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(puts #+test-on "selected" #-test-on "rejected")
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(puts GREETING)
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#+(and test-on (not test-off)) (puts "and-not")
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#-test-on (puts "never printed")
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(return 0))
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