C preprocessor internals (opens in new tab)

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92 pointsg3orge12y ago4 comments

4 comments

Turns out the preprocessor is actually an organically grown pseudo language (as opposed to a properly designed language feature) inside C, which later got standardized through an incredibly complex set of rules and definitions.

This can be used to explain much of C. :)

ot12y ago

An impressive application of the C preprocessor is the Boost.Preprocessor library [1]. It basically implements a primitive (and bounded) version of Lisp inside the preprocessor.

I used it once to write DSLs to define data structures, where a few lines of code were expanded to hundreds of lines of templates, (de)serialization code, etc...

[1] http://www.boostpro.com/mplbook/preprocessor.html

tensaix2j12y ago

This reminds me of one of the assignments in cppgm.org, where you get to implement all those features. http://www.cppgm.org/pa4.html

octo_t12y ago

i like how one of the assignments is "read the C++ spec" o_O

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