我怎样才能prevent需要复制传递给AVR-GCC C ++的构造函数的字符串？ [英] How can I prevent the need to copy strings passed to a avr-gcc C++ constructor?

问题描述

在 ArduinoUnit 单元测试库我提供了一个机制给一个TestSuite一个名字。图书馆的用户可以编写如下：

In the ArduinoUnit unit testing library I have provided a mechanism for giving a TestSuite a name. A user of the library can write the following:

TestSuite suite("my test suite");
// ...
suite.run(); // Suite name is used here

这是预期的用法 - TestSuite的名称是一个字符串。但是到prevent难以发现的错误，我觉得有义务满足不同用途，例如：

This is the expected usage - the name of the TestSuite is a string literal. However to prevent hard-to-find bugs I feel obliged to cater for different usages, for example:

char* name = (char*) malloc(14);
strcpy(name, "my test suite");
TestSuite suite(name);
free(name);
// ...
suite.run(); // Suite name is used here

因此​​我已经实现的TestSuite是这样的：

As such I have implemented TestSuite like this:

class TestSuite {
public:
  TestSuite(const char* name) {
    name_ = (char*) malloc(strlen(name) + 1);
    strcpy(name_, name);
  }

  ~TestSuite() {
    free(name_);
  }

private:
  char* name_;
};

先不谈这个问题未能应对我preFER简单地将指针分配给这样的成员变​​量的构造内存分配失败的：

Putting aside the issue of failing to deal with memory allocation failures in the constructor I'd prefer to simply allocate the pointer to a member variable like this:

class TestSuite {
public:
  TestSuite(const char* name) : name_(name) {
  }

private:
  const char* name_;
};

有没有什么办法可以更改界面，迫使它要使用'正确'，这样我可以做废除了动态内存分配？

Is there any way I can change the interface to force it to be used 'correctly' so that I can do away with the dynamic memory allocation?

推荐答案

如果你提供什么样的两个重载构造函数？

What if you provide two overloaded constructors?

TestSuite(const char* name) ...
TestSuite(char* name) ...

如果用为const char * 调用，然后构造可以使指针的拷贝，假设该字符串不会消失。如果用的char * 调用构造可以使整个字符串的副本。

If called with a const char*, then the constructor could make a copy of the pointer, assuming that the string will not go away. If called with a char*, the constructor could make a copy of the whole string.

请注意，它仍然有可能通过传递为const char * 来构造时，名称其实是在动态分配。然而，这可能足以满足您的目的。

Note that it is still possible to subvert this mechanism by passing a const char* to the constructor when the name is in fact dynamically allocated. However, this may be sufficient for your purposes.

我要指出，我从来没有真正看到了一个API中使用这种技术，它只是因为我是读你的问题是发生在我一个想法。

I should note that I have never actually seen this technique used in an API, it was just a thought that occurred to me as I was reading your question.

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