製作出計算變量的目標在化妝

Question

這裏是行不通

say-hello := greeting 
say-bye := farewell 

greeting: 
    @echo "Hello" 

farewell: 
    @echo "Bye" 

.SECONDEXPANSION: 
%-guvnah: $$(say-$*) 
    @echo "Target was: $(say-$*)" 

該命令的示例

make hello-guvnah 

應該產生

hello 
Target was: greeting 

但只有

顯示

Target was: greeting 

Answer 1

它將如果你加倍逃脫的先決條件$*所以它得到二次擴張，而不是在第一遍期間擴大：$$（聲言如下─％）：

.SECONDEXPANSION: 
%-guvnah: $$(say-$$*) 
    @echo "Target was: $(say-$*)"