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5.2 If Statements ¶

• When the if, elsif or else keywords fit on the same line with the condition and the then keyword, then the statement is formatted as follows:

  if condition then
     ...
  elsif condition then
     ...
  else
     ...
  end if;
  

  When the above layout is not possible, then should be aligned with if, and conditions should preferably be split before an and or or keyword a follows:

  if long_condition_that_has_to_be_split
    and then continued_on_the_next_line
  then
     ...
  end if;
  

  The elsif, else and end if always line up with the if keyword. The preferred location for splitting the line is before and or or. The continuation of a condition is indented with two spaces or as many as needed to make nesting clear. As an exception, if conditions are closely related either of the following is allowed:

  if x = lakdsjfhlkashfdlkflkdsalkhfsalkdhflkjdsahf
       or else
     x = asldkjhalkdsjfhhfd
       or else
     x = asdfadsfadsf
  then
    ...
  end if;
  
  if x = lakdsjfhlkashfdlkflkdsalkhfsalkdhflkjdsahf or else
     x = asldkjhalkdsjfhhfd                         or else
     x = asdfadsfadsf
  then
    ...
  end if;
  

• Conditions should use short-circuit forms ( and then, or else ), except when the operands are boolean variables or boolean constants.
• Complex conditions in if statements are indented two characters:

  if this_complex_condition
    and then that_other_one
    and then one_last_one
  then
     ...
  end if;
  

  There are some cases where complex conditionals can be laid out in manners that do not follow these rules to preserve better parallelism between branches, e.g.

  if xyz.abc (gef) = 'c'
       or else
     xyz.abc (gef) = 'x'
  then
     ...
  end if;
  

• Every if block is preceded and followed by a blank line, except where it begins or ends a sequence_of_statements.

  A := 5;
  
  if A = 5 then
     null;
  end if;
  
  A := 6;