Is it possible to read a file at compile time?

Question

I am wondering if it is possible in C++11/14 to actually read files at compile time. For example the following code will only compile if it can successfully read the file.

constexpr std::string shader_source = load("~/foo.glsl"); 

Do you think this could be possible?

I know that I could do this with some custom tool when building my application.

Answer 1

Building on teivaz's idea, I wonder if the usual "stringize after expansion" trick will work:

#define STRINGIZE(...) #__VA_ARGS__ #define EXPAND_AND_STRINGIZE(...) STRINGIZE(__VA_ARGS__)  constexpr std::string shader_source = EXPAND_AND_STRINGIZE( #include "~/.foo.glsl" ); 

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Still, I would go for a conventional extern const char[] declaration resolved to the content by the linker. The article "Embedding a File in an Executable, aka Hello World, Version 5967" has an example:

# objcopy --input binary \           --output elf32-i386 \           --binary-architecture i386 data.txt data.o 

Naturally you should change the --output and --binary-architecture commands to match your platform. The filename from the object file ends up in the symbol name, so you can use it like so:

#include <stdio.h>  /* here "data" comes from the filename data.o */ extern "C" char _binary_data_txt_start; extern "C" char _binary_data_txt_end;  main() {     char*  p = &_binary_data_txt_start;      while ( p != &_binary_data_txt_end ) putchar(*p++); }