is it bad practice to....

[abrege]

....define functions inside a class, like this

class Blah
{
public:
     Blah()
     {
           // .....
     }
};

rather than like this

class Blah
{
public:
     Blah();
};

Blah::Blah()
{
     // .....
}

???

[Cela]

The effect is different. If you define a method inside the class then the method is taken to be inline, if you define it outside of the class then you have the option of making it inline if you want, but it isn't by default. As for good and bad practice, it doesn't really effect readability or do anything really bad, so no worries either way :-)

[abrege]

Thanks!

[Yawgmoth]

What's the difference between inline and noninline functions?

[beege31337]

as far as OOP goes I would say defining the class defininitions in a .h file
and the implementation in another file is better then grouping it all together.

in other words it is good to separate interface from implementation.

so i would do

Blah.h

class Blah
{
public:
     Blah();
};

and
Blah.cc

#include"Blah.h"

Blah::Blah()
{
     // .....
}

This may also speed up you compilation a little bit

[grib]

Inline functions are expanded macro-like every time they are called thus

class myclass {
   int *data;
public:
   myclass(int size=10) : data(new int[size]) {};
   int & operator [] (int n) {return data[n];}
   ~myclass() { delete [] data;}
};

int main() {
  myclass a;
  a[5] = a[3] + a[2];
  return 0;
}
//is compiled as:
  myclass a;
  a.data = new int[10];  // mild magic here
  a.data[5] = a.data[3] + a.data[2]; 
  delete [] data; // more magic
  return 0;

The upside is that you don't pay overhead for function calls, the downside is that your programs get bigger and compilation takes longer.

[Munkey01]

Originally posted by beege31337
as far as OOP goes I would say defining the class defininitions in a .h file
and the implementation in another file is better then grouping it all together.

in other words it is good to separate interface from implementation.

Well if the source file isn't too long then I see nothing wrong with having the class declarations and everything else being in the source file as well. Same goes if you are posting the code on a board such as this one. Also how would that speed up compilation? It would need to open the header file also, seems to me it would be slower...

[beege31337]

Originally posted by Munkey01
Also how would that speed up compilation? It would need to open the header file also, seems to me it would be slower...

I was saying that abt. the possibility of speeding compilation because if you have everything in one file, everytime you compile ( or more specifically make ) your program, everything is recompiled.

but if you have the class definintions separate from the classes ( in a .h ) then the implementation of the class ( which is compiled into an object file ) doesn't have to be recompiled everytime another program uses the class.
If you have the definitions and implementation grouped into the same file then everytime you use the class it must be recompiled. One of the reasons we have .h files is to prevent this need for recompilation.