为什么模板函数不能具有extern“C”。连锁？ [英] why can't a template function have extern "C" linkage?

问题描述

标题说明了一切。


我可以看到一个函数直接从C调用的情况，

名称将会出现问题这个。


但是我看不出为什么模板函数不能给出extern的原因

" C"将它分配给C函数指针的链接。


Ian

解决方案

Ian< no***@nowhere.com>在新闻中写道：1122500290.491907@drone2-svc-

skyt.qsi.net.nz：

标题说明了一切。
名称将会填满这个。

但我看不出模板的原因功能不能给予外部
C将它分配给C函数指针的链接。

Ian

嗯......你的C程序怎么样（不会什么都不知道

模板）包括声明模板函数的头文件？

请记住模板函数实际上并不存在实例化了......（不确定实例化是正确的词......）

Andre Kostur写道：

[..]
请记住，模板函数在实例化之前实际上并不存在....（不确定实例化是否为正确的话....）

这是正确的词。


V

Andre Kostur写道：

Ian< no *** @ nowhere.com>在新闻中写道：1122500290.491907@drone2-svc-
skyt.qsi.net.nz：

标题说明了一切。
名称将会填满这个。

但我看不出模板的原因功能不能给予外部
C它被分配给C函数指针的链接。

Ian

嗯...你的C程序怎么样（不知道关于
模板的任何内容包括声明模板函数的头文件？
请记住，模板函数在实例化之前并不存在....（不是确定实例化是正确的词......）

正如我所说，我理解为什么这种情况不可能，但问题我

涉及为C驱动程序设置一些回调。驱动程序API有一个

的结构数，其中包含各种回调的函数指针。


因此在这种情况下，C函数指针将在C ++代码中赋值，模板实例化后，
。这些名字与C代码无关。


Ian

The title says it all.

I can see the case where a function is to be called directly from C, the
name mangling will stuff this up.

But I can''t see a reason why a template function can''t be given extern
"C" linkage where it is to be assigned to a C function pointer.

Ian

解决方案

Ian <no***@nowhere.com> wrote in news:1122500290.491907@drone2-svc-
skyt.qsi.net.nz:

The title says it all.

I can see the case where a function is to be called directly from C, the
name mangling will stuff this up.

But I can''t see a reason why a template function can''t be given extern
"C" linkage where it is to be assigned to a C function pointer.

Ian

Um... how would your C program (which doesn''t know anything about
templates) include the header file where the template function is declared?
Keep in mind that a template function doesn''t actually exist until it is
instantiated.... (not sure that "instantiated" is the right word....)

Andre Kostur wrote:

[..]
Keep in mind that a template function doesn''t actually exist until it is
instantiated.... (not sure that "instantiated" is the right word....)

It is the right word.

V

Andre Kostur wrote:

Ian <no***@nowhere.com> wrote in news:1122500290.491907@drone2-svc-
skyt.qsi.net.nz:

The title says it all.

I can see the case where a function is to be called directly from C, the
name mangling will stuff this up.

But I can''t see a reason why a template function can''t be given extern
"C" linkage where it is to be assigned to a C function pointer.

Ian

Um... how would your C program (which doesn''t know anything about
templates) include the header file where the template function is declared?
Keep in mind that a template function doesn''t actually exist until it is
instantiated.... (not sure that "instantiated" is the right word....)

As I said, I understand why this case can''t be, but the problem I had
involved setting up some callbacks for a C driver. The driver API has a
number of structs with function pointers for various callbacks.

So in this case, the C function pointers will be assigned in C++ code,
after the templates have been instantiated. the names are irrelevant to
the C code.

Ian

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