GNU Make:在模式规则宏中使用％ [英] GNU Make: Using % in a pattern-rule macro

问题描述

我正在尝试构建一个模式规则，该规则允许我在宏调用中使用%，但未获得预期的结果.

I'm trying to build a pattern-rule that allows me to use % in a macro call and I'm not getting the results I expect.

模式规则:

%.o: %.cpp $(%_H)
    g++ -o $@ $(FLAGS) -c $<

问题出在$(％_ H)

The problem is with the $(%_H)

由于某些原因，%没有扩展到定义的位置.

For some reason % isn't expanding to what it is defined to.

当我打印出依赖项列表($^)时，仅打印源文件.

When I print out the dependency list ($^), only the source file prints.

我有一种非常干净的方式来设置我想使用的依赖项:

I have a very clean way of setting up my dependencies that I would like to use:

# Header Dependencies per object 
Geometry_H:=Geometry.h $(Error_H) 
Enemy_H:=Enemy.h $(Geometry_H) $(Error_H) 
Surface_H:=Surface.h $(Geometry_H) 
Player_H:=Player.h $(Geometry_H) $(Surface_H) 
SDLWindow_H:=SDLWindow.h $(Surface_H) $(Error_H) 
Path_H:=Path.h $(Geometry_H) $(Error_H) 
Territory_H:=Territory.h $(Geometry_H) 
Board_H:=Board.h $(Territory_H) $(Geometry_H) $(Player_H) $(Path_H) $(Enemy_H) $(Error_H) 
Error_H:=Error.h 
Diminisher_H:=Diminisher.h $(SDLWindow_H) $(Geometry_H) $(Surface_H) $(Board_H) $(Error_H) 
Main_H:=$(Diminisher_H)

另一个人建议我将这些变量更改为依赖项列表.

Another person has suggested that I change these variables into dependency lists.

即 Main_H:= $(Diminisher_H)

I.e. Main_H:=$(Diminisher_H)

成为 Main.o:$(Diminisher_H)

becomes Main.o: $(Diminisher_H)

这是一个很好的解决方案，它可以正常工作. 但是，问题仍然在于$(%_H)某种程度上是无效的.

This is a good fix, it works. However, the problem still remains that $(%_H) is somehow invalid.

我想知道如何(如果可能)使其成为有效的表达式.

I would like to know how (if possible) to make it a valid expression.

我已经尝试过$( $%_H )，$( $(%)_H )，$( $(value %)_H )等. 似乎%在进行宏调用时就失去了意义.

I've tried $( $%_H ), $( $(%)_H ), $( $(value %)_H ) and many more. It seems like % just loses its meaning when in a macro call.

无法在宏调用中使用%吗?

Is there no way to use % in a macro call?

推荐答案

都可以使用二次扩展:

.SECONDEXPANSION:

%.o: %.cpp $$($$*_H)
    g++ -o $@ $(FLAGS) -c $<

或者(IMO，更好)使用依赖项自动生成:

Or (IMO, better) use dependency auto-generation:

• 另一个SO问题的答案
• 高级自动依赖项生成文章

• An answer to another SO question
• Advanced Auto-Dependency Generation article

这篇关于GNU Make:在模式规则宏中使用％的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！