prefer-case-to-elseif.md

September 23, 2022 · View on GitHub

Conditions with many branches, i.e. IF statements with many ELSEIF alternatives, are often hard to read. When applicable, a CASE statement where all branches are on equal footing as WHEN branches is often much more readable.

The check reports a finding when the number of branches exceeds a configurable threshold.

How does the check work?

The check finds IF-ELSEIF chains where each condition consists only of a single logical expression and the first token of all logical expressions is the same.

How to solve the issue?

Use CASE instead of ELSEIF for multiple alternative conditions.

What to do in case of exception?

In exceptional cases, you can suppress this finding by using the pseudo comment "#EC PREFER_CASE.

IF type = type-some_type. "#EC PREFER_CASE
  " ...
ELSEIF type = type-some_other_type.
  " ...
ELSE.
  RAISE EXCEPTION NEW /dirty/unknown_type_failure( ).
ENDIF.

Example

Before the check:

IF type = types-some_type.
  " ...
ELSEIF type = types-some_other_type.
  " ...
ELSE.
  RAISE EXCEPTION NEW /dirty/unknown_type_failure( ).
ENDIF.

After the check:

CASE type.
  WHEN type-some_type.
    " ...
  WHEN type-some_other_type.
    " ...
  WHEN OTHERS.
    RAISE EXCEPTION NEW /clean/unknown_type_failure( ).
ENDCASE.

prefer-case-to-elseif.md