我试图获得一个短代码函数（newStuff）来显示另一个函数（oldStuff）的内部，但我遇到了麻烦。下面列出了两个短代码函数，以及我尝试过的功能。有人能帮我在“oldStuff”函数中显示“newStuff”函数吗？

谢谢

Current Functions

function newStuff(){
return \'
only raw html is in this function
\';
}
add_shortcode(\'new\', \'newStuff\');

function oldStuff(){
return \'
only raw html is in this function
\';
}
add_shortcode(\'old\', \'oldStuff\');

I tried including the short code, but it didn\'t work

function oldStuff(){
return \'
[new]
only raw html is in this function
\';
}
add_shortcode(\'old\', \'oldStuff\');

I tried including the function, but it didn\'t work

function oldStuff(){
return \'
echo newStuff();
only raw html is in this function
\';
}
add_shortcode(\'old\', \'oldStuff\');