是否可以在编译时读取文件？ [英] Is it possible to read a file at compile time?

问题描述

我想知道是否可能在C ++ 11/14在编译时实际读取文件。例如，下面的代码只有编译成功才能成功读取该文件。

  constexpr std :: string shader_source = load 〜/ foo.glsl）;你认为这是可能的吗？
 
 
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解决方案
我知道我可以使用一些自定义工具在构建应用程序时执行此操作。 基于teivaz的想法，我想知道通常的stringize after expansion技巧是否可以工作：
  #define STRINGIZE ...）#__VA_ARGS__ 
 #define EXPAND_AND_STRINGIZE（...）STRINGIZE（__ VA_ARGS__）
 
 constexpr std :: string shader_source = EXPAND_AND_STRINGIZE（
 #include〜/ .foo .glsl
）; 
  
  
 
 
 
 
 
 
仍然，我会去一个常规的 extern const char [] 声明由链接器解析到内容。文章将文件嵌入可执行文件（又称Hello World），版本5967 有一个例子：
 ＃objcopy --input binary \ 
 --output elf32- i386 \ 
 --binary-architecture i386 data.txt data.o 
  
应该更改  -  output 和  -  binary-architecture 命令以匹配您的平台。对象文件中的文件名以符号名称结尾，因此您可以这样使用：
  #include< stdio .h> 
 
 / *这里data来自文件名data.o * / 
 externCchar _binary_data_txt_start; 
 externCchar _binary_data_txt_end; 
 
 main（）
 {
 char * p =& _binary_data_txt_start; 
 
 while（p！=& _binary_data_txt_end）putchar（* p ++）; 
} 
  
 
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.
解决方案
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"
);




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++);
}


                        
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