[vtk-developers] PROPOSAL: Changing VTK's indentation style

[Andras Lasso]

I would not worry too much about Slicer extensions. For example in our extensions we already use the usual indentation instead of VTK’s.

Note that ITK, Paraview, etc. would need to be updated to the same style, too.

Andras

From: vtk-developers [mailto:vtk-developers-bounces at vtk.org] On Behalf Of Steve Pieper
Sent: September 9, 2015 6:27 PM
To: David Gobbi <david.gobbi at gmail.com>
Cc: VTK Developers <vtk-developers at vtk.org>; Brad King <brad.king at kitware.com>
Subject: Re: [vtk-developers] PROPOSAL: Changing VTK's indentation style

I'd personally vote for:

int func( int arg )
{
  // this code looks gorgeous!
  if ( condition ) {
    statement;
  } else {
    statement;
  }
}

But I'm also used to VTK's "unorthodox" style and don't really mind it.  To be honest it makes it very clear when I'm looking at VTK code and when code has been written by novices vs old hands (and yes, sometimes I form opinions about likely code quality from that).

I'd also like to point out that in Slicer our explicit style [1] is to copy VTK style for any code that inherits from VTK objects.  So if VTK changes Slicer will have to also, and by implication all Slicer extensions should also change.  This will create extra maintenance work and probably some confusion for our community (and I suspect other projects will have similar issues).

Is the motivation for this change really worth introducing some busywork and confusion for people who use VTK?  If yes, then +1.

-Steve

[1] http://www.slicer.org/slicerWiki/index.php/Documentation/Nightly/Developers/Style_Guide



On Wed, Sep 9, 2015 at 6:05 PM, David Gobbi <david.gobbi at gmail.com<mailto:david.gobbi at gmail.com>> wrote:
Hi Brad,

Even though I slightly prefer the inline "if () {" style, I can offer some arguments against it.

1) it doesn't work well for multi-line conditionals:

    for (std::vector<typeWithLongName>::iterator iter = vec.begin();
          iter != vec.end();
          ++iter) {
      statements;
    }

versus

    for (std::vector<typeWithLongName>::iterator iter = vec.begin();
          iter != vec.end();
          ++iter)
    {
      statements;
    }

2) it's inherently inconsistent.  This is demonstrated by the following Java-styled code that actually applies the style consistently:

    int myfunc(int x) {
      if (x == 0) {
        statements;
      }
    }

Most C++ programmers (like myself) think the above is ridiculous, but really, why should a definition block be treated differently from a conditional block?

In my opinion, putting the brace on the following line is nice because it is a simple, consistent rule that produces easily readable code.

I'm a fan of compact code, but only when it is compactified according to my own tastes.  Otherwise the compactification loses its value ;-)

 - David


On Wed, Sep 9, 2015 at 3:29 PM, Brad King <brad.king at kitware.com<mailto:brad.king at kitware.com>> wrote:
On 9/9/2015 3:41 PM, Brad King wrote:
>   if (...) {
>     ...
>   } else {
>     ...
>   }
[snip]
>   if (...)
>   {
>     ...
>   }
>   else
>   {
>     ...
>   }

There seems to be agreement that either of these is an improvement
but that we should choose now which one to use.  I'm sure one can
find endless debates across the web about which one is best.  Here
are the main reasons I prefer the former over the latter:

1. Uses less vertical space.  This is important when the content
   within the blocks is short.

2. The start and end of each logical block is aligned horizontally
   and can be matched vertically with nothing in the way:

     if (...) {
     ^  ...
     |  ...
     |  ...
     |  ...
     |  ...
     v  ...
     } else {
     ^  ...
     |  ...
     |  ...
     |  ...
     |  ...
     v  ...
     }

   This is important when the content within the blocks is long.

3. Distinguishes conditional and unconditional blocks:

     if (...) {
        // conditional block
     }

     {
       // unconditional block
     }

   Contrast this to the latter style where both look the same:

     if (...)
     {
       // conditional block
     }

     {
       // unconditional block
     }

   In the latter style one must read a line above the "{" to see
   whether it is a condition.  This could be tricky if there is
   an unrelated f(...) call there.

The former style is widely used in many projects and well-supported
by editors.

-Brad
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