具有数据存储库的C ++ Bazel项目 [英] C++ Bazel project with a Data repository

问题描述

我有一个(基本)C ++项目:

I have a (basic) C++ project:

├── bin
│   ├── BUILD
│   ├── example.cpp
├── data
│   └── someData.txt
└── WORKSPACE

其中可执行文件 example.cpp 使用data/目录中的一些数据文件:

where the executable example.cpp use some data files from data/ directory:

#include <fstream>
#include <iostream>

int main()
{
  std::ifstream in("data/someData.txt");

  if (!in)
  {
    std::cerr << "Can not open file!";
    return EXIT_FAILURE;
  }

  std::string message;

  if (!(in >> message))
  {
    std::cerr << "Can not read file content!";
    return EXIT_FAILURE;
  }

  std::cout << message << std::endl;

  return EXIT_SUCCESS;
}

我的Bazel设置是最小的设置:

My Bazel setup is the minimal one:

• WORKSPACE :空文件
• bin/BUILD :cc_binary(name = "example",srcs = ["example.cpp"])
• data/someData.txt :包含Hello_world!行

• WORKSPACE: empty file
• bin/BUILD: cc_binary(name = "example",srcs = ["example.cpp"])
• data/someData.txt: contains the Hello_world! line

问题是Bazel将所有这些文件移动到特殊位置:

The problem is that Bazel moves all these files in special locations:

.
├── bazel-Bazel_with_Data -> ...
├── bazel-bin -> ...
├── bazel-genfiles -> ...
├── bazel-out -> ...
├── bazel-testlogs -> ...

示例特有的可执行文件找不到 data/someData.txt 文件:

In peculiar the example executable will not found the data/someData.txt file:

bazel run bin:example

将打印:

INFO: Analysed target //bin:example (0 packages loaded).
INFO: Found 1 target...
Target //bin:example up-to-date:
  bazel-bin/bin/example
INFO: Elapsed time: 0.101s, Critical Path: 0.00s
INFO: Build completed successfully, 1 total action

INFO: Running command line: bazel-bin/bin/example
Can not open file!ERROR: Non-zero return code '1' from command: Process exited with status 1

问题是如何进行管理?

我希望示例可执行文件能够找到 Data/someData.txt 文件.

I want the example executable to be able to find the Data/someData.txt file.

推荐答案

注意::此解决方案似乎无法在Windows下运行(请参见注释).

CAVEAT: it seems this solution does not work under Windows (see comments).

必须在 data 目录中创建一个额外的 BUILD 文件，该文件定义必须导出的数据文件.现在的项目结构为:

One must create an extra BUILD file in the data directory that defines what data files must be exported. The project structure is now:

├── bin
│   ├── BUILD
│   ├── example.cpp
├── data
│   ├── BUILD
│   └── someData.txt
└── WORKSPACE

此新的数据/内置文件为:

exports_files(["someData.txt"])

然后修改了 bin/BUILD 文件以添加 someData.txt 依赖项:

And the bin/BUILD file is modified to add the someData.txt dependency:

cc_binary(
    name = "example",
    srcs = ["example.cpp"],
    data = ["//data:someData.txt"],
)

现在，如果您运行:

bazel run bin:example

您应该得到:

INFO: Analysed target //bin:example (2 packages loaded).
INFO: Found 1 target...
Target //bin:example up-to-date:
  bazel-bin/bin/example
INFO: Elapsed time: 0.144s, Critical Path: 0.01s
INFO: Build completed successfully, 3 total actions

INFO: Running command line: bazel-bin/bin/example
Hello_world!

表示示例可执行文件已找到 data/someData.txt 文件并打印了其内容.

meaning that the example executable has found the data/someData.txt file and printed its content.

还请注意，您可以对

 cc_test(...,data =["//data:someData.txt"], )

您可以从 GitHub存储库中复制此注释.

You can reproduce this note from this GitHub repo.

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