How do you write a no-op statement?

Question

What is the best way to write a no-op statement in Delphi?

Take this code:

if a=b then
  SomeOldStatement
else
  AnotherStatement;

And say that you temporarily want to rem out SomeOldStatement.

Would you just go for this solution:

if a=b then
  //SomeOldStatement
else
  AnotherStatement;

Personally I don't like the empty then section and would like to have something compilable in there...

if a=b then
  NoOp
  //SomeOldStatement
else
  AnotherStatement;

Answer 1

Not sure why you need anything there at all (e.g. I'm happy with "then else").

But if you want something compilable there, I would do this:

if a=b then
  begin end
  //SomeOldStatement
else
  AnotherStatement;

An empty begin block is the best noop I know of in Delphi. It will produce no assembler code and thus no overhead.

Answer 2

if a=b then 
  SomeOldStatement 
else 
  AnotherStatement; 

should be written as

if a=b then
begin
  SomeOldStatement;
end 
else
begin
  AnotherStatement; 
end;

now, you can comment out SomeOldStatement; with exactly the effect you are after, the debugger more accurately follows the flow of the code AND you avoid bizarre side effects in code like

if a=b then
  if b=c then
    statement1
  else
    if c=d then
      statement2;
  else
   statement2
else 
  statement3;

screw up your indenting, get a semicolon wrong, document out a line for testing and holy crap, things get ugly fast.

seriously, try figuring out if the code I just wrote there is even valid without a compiler pass.

now, guess what happens with this:

if a=b then
if b=c then
statement1
else
if c=d then
statement2;
// else
statement2
else 
statement3;

also:

if a=b then
  statement1;
  statement2;

can often do strange things, and even stranger things when you do

if a=b then
//  statement1;
statement2;

serious - just get in the habit of ALWAYS having begin ends in all your logic - it makes your code easier to follow, avoids side effects, avoids mental parsing errors, code parsing errors and commenting out side effects.

Plus, an empty begin/end is the same as your no-op.