NAME

Perl::Critic::Policy::CodeLayout::RequireFinalSemicolon - require a semicolon at the end of code blocks

DESCRIPTION

This policy is part of the Perl::Critic::Pulp add-on. It asks you to put a semicolon ; on the final statement of a subroutine or block.

    sub foo {
      do_something();      # ok
    }

    sub bar {
      do_something()       # bad
    }

The idea is that if you add more code you don't have to notice the previous line needs a terminator. It's also more like the C language, if you consider that a virtue.

This is only a matter of style since the code runs the same either way, and on that basis this policy is low severity and under the "cosmetic" theme (see "POLICY THEMES" in Perl::Critic).

Same Line Closing Brace

By default (see "CONFIGURATION" below), a semicolon is not required when the closing brace is on the same line as the last statement. This is good for constants and one-liners.

    sub foo { 'my-constant-value' }     # ok

    sub square { return $_[0] ** 2 }    # ok

Final Value Expression

A semicolon is not required in places where the last statement is an expression giving a value.

    map { some_thing();
          $_+123             # ok
        } @values;

    do {
      foo();
      1+2+3                  # ok
    }

This currently means

    do grep map sort                         # builtins

    reduce any all none notall first         # List::Util
    pairfirst pairgrep pairmap

    mapp map_pairwise grepp grep_pairwise    # List::Pairwise
    firstp first_pairwise lastp last_pairwise 

These module function names are always treated as expressions. There's no check for whether the respective module is actually in use. Fully qualified names like List::Util::first are recognised too.

do {} while or do {} until loops are ordinary blocks, not expression blocks, so still require a semicolon on the last statement inside.

    do {
      foo()                  # bad
    } until ($condition);

Try/Catch Blocks

The Try, TryCatch and Syntax::Feature::Try modules all add try block forms. These are blocks not requiring a terminating semicolon, the same as an if etc doesn't.

    use TryCatch;
    sub foo {
      try {
          attempt_something();
      } catch {
          error_recovery();
      } # ok, no semi required here for TryCatch
    }

The insides of the try and catch are the same as other blocks, but the try statement itself doesn't require a semicolon. (See policy ValuesAndExpressions::ProhibitNullStatements to notice one added unnecessarily.)

For reference, PPI doesn't know try/catch specifically, so when they don't have a final semicolon the next statement runs together and the nature of those parts might be lost. This could upset things like recognition of for loops and could potentially make some perlcritic reports go wrong.

The try/catch block exemption here is only for the modules with this block syntax. There are other try modules such as Try::Tiny and friends where a final semicolon is normal and necessary if more code follows (because their try and catch are ordinary function calls prototyped to take code blocks).

    use Try::Tiny;
    sub foo {
      try {
          attempt_something();
      } catch {
          error_recovery();
      } # bad, semi required here for Try::Tiny
    }

Disabling

If you don't care about this you can always disable from your .perlcriticrc file in the usual way (see "CONFIGURATION" in Perl::Critic),

    [-CodeLayout::RequireFinalSemicolon]

CONFIGURATION

except_same_line (boolean, default true)

If true (the default) then don't demand a semicolon if the closing brace is on the same line as the final statement.

    sub foo { return 123 }     # ok  if "except_same_line=yes"
                               # bad if "except_same_line=no"

except_expression_blocks (boolean, default true)

If true (the default) then don't demand a semicolon at the end of an expression block, as described under "Final Value Expression" above.

    # ok under "except_expression_blocks=yes"
    # bad under "except_expression_blocks=no"
    do { 1+2+3 }               
    map { $_+1 } @array
    grep {defined} @x

The statements and functions for this exception are currently hard coded. Maybe in the future they could be configurable, though multi-line expressions in this sort of thing tends to be unusual anyway. (See policy BuiltinFunctions::RequireSimpleSortBlock for example to demand sort is only one line.)

BUGS

It's very difficult to distinguish a code block from an anonymous hashref constructor if there might be a function prototype in force, eg.

    foo { abc => 123 };   # hash ref normally
                          # code block if foo() has prototype

PPI tends to assume code. RequireFinalSemicolon currently assumes hashref so as to avoid false violations. Any try, catch or finally are presumed to be code blocks (the various Try modules). Perhaps other common or particular functions or syntax with code blocks could be recognised. In general this sort of ambiguity is another good reason to avoid function prototypes.

PPI as of its version 1.270 sometimes takes hashrefs in lists and arrarefs to be code blocks, eg.

    ppidump 'foo({%y,x=>1})'
    ppidump '[{%y,x=>1}]'

    ppidump '[{x=>1,%y}]'       # ok, hash

SEE ALSO

Perl::Critic::Pulp, Perl::Critic, Perl::Critic::Policy::CodeLayout::RequireTrailingCommas, Perl::Critic::Policy::CodeLayout::RequireTrailingCommaAtNewline, Perl::Critic::Policy::Subroutines::RequireFinalReturn, Perl::Critic::Policy::ValuesAndExpressions::ProhibitNullStatements, Perl::Critic::Policy::BuiltinFunctions::RequireSimpleSortBlock

List::Util, List::Pairwise, Try, TryCatch, Syntax::Feature::Try

HOME PAGE

http://user42.tuxfamily.org/perl-critic-pulp/index.html

COPYRIGHT

Copyright 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2019, 2021 Kevin Ryde

Perl-Critic-Pulp is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.

Perl-Critic-Pulp is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with Perl-Critic-Pulp. If not, see <http://www.gnu.org/licenses>.

cpanm Perl::Critic::Pulp

perl -MCPAN -e shell
install Perl::Critic::Pulp