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Editorial Team
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Asked: 2026-05-16T08:19:27+00:00

I’ve found some weird C++ preprocessor clauses, like: #define COMPILER_FLOAT_ENTRIES_DO(template) and #define COMPILER_FLOAT_ENTRIES_DO(template) \

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I’ve found some weird C++ preprocessor clauses, like:

#define COMPILER_FLOAT_ENTRIES_DO(template)

and 

#define COMPILER_FLOAT_ENTRIES_DO(template) \
  template(jvm_fadd)  \
  template(jvm_fsub)  \
  template(jvm_f2d)

What does passing “template” reserved word to a #define, and calling template(something) mean? I couldn’t find anything at Google; probably because “#define” and “template” are really common words.

The entire code is at https://phoneme.dev.java.net/source/browse/phoneme/components/cldc/trunk/src/vm/share/ROM/ROMWriter.hpp?rev=19839&view=markup.

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1 Answer

  1. Editorial Team
    #define COMPILER_FLOAT_ENTRIES_DO(template)

    so COMPILER_FLOAT_ENTRIES_DO(x) gets replaced with with ”. In other words, it removes that macro from the code.

    #define COMPILER_FLOAT_ENTRIES_DO(template) \
  template(jvm_fadd)  \
  template(jvm_fsub)  \
  template(jvm_f2d)

    so COMPILER_FLOAT_ENTRIES_DO(x) gets replaced with x(jvm_fadd) x(jvm_fsub) x(jvm_f2d).

    If all else fails, you can see what is happening with macros by using g++ -E -o foo.cpp to leave the output of macro preprocessing in foo.cpp. Of course you’ll need all the other compilation flags passed in by command line as well (especially -D and -I flags).

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