quick_start.md

Quick Start

Let's start with a hello-world to practice using Blade.

Create a workspace

$ mkdir quick-start
$ cd quick-start
$ touch BLADE_ROOT

Define and implement the say library

Create the header file say.h:

#pragma once
#include <string>

// Say a message
void Say(const std::string& msg);

Create the implementation file say.cpp:

#include "say.h"
#include <iostream>

void Say(const std::string& msg) {
    std::cout << msg << "!\n";
}

Create a BUILD file and describe the above file as a say library:

cc_library(
    name ='say',
    hdrs = ['say.h'],
    srcs = ['say.cpp'],
)

cc_library means that this is a C/C++ library, hdrs means the library’s public interface header files, and srcs means its implementation files. If there are private header files, also put them in srcs.

Define and implement the hello library

Create the header file hello.h:

#pragma once
#include <string>

// Say hello to `to`
void Hello(const std::string& to);

Create the implementation file hello.cpp:

#include "say.h"

void Hello(const std::string& to) {
    Say("Hello, "+ to);
}

Create a BUILD file and describe the above file as a hello library:

cc_library(
    name ='hello',
    hdrs = ['hello.h'],
    srcs = ['hello.cpp'],
    deps = [':say'],
)

It looks similar to the say library, but with an additional deps parameter, which means it depends on the say library. The : prefix indicates that the target is in the same BUILD file.

Implement the hello-world program

Create the hello-world.c file:

#include "hello.h"

int main() {
    Hello("World");
    return 0;
}

Add the rule call for compiling hello-world in the BUILD file:

cc_binary(
    name ='hello-world',
    srcs = ['hello-world.c'],
    deps = [':hello'],
)

Note that the rule name is cc_binary, the dependency on the hello library needs to be added to the deps, but there is no need to add the dependency on the say library, because this is the implementation details of hello, the hello-world target does not need to be understood. When compiling and linking, Blade will correctly handle the transfer of dependencies.

Build the hello-world program:

$ blade build :hello-world
Blade(info): Building...
Blade(info): Build success.

Run the hello-world program:

$ blade run :hello-world
Blade(info): Building...
Blade(info): Build success.
Blade(info): Run'['/data1/code/blade-build/example/quick-start/build64_release/hello-world']'
Hello, World!

For a complete example, see quick-start under example.