Over the last few days I have twice seen answers to questions on this site advocating a foreach loop construct which has made me scratch my head somewhat. These answers have been in no way wrong, but, to my mind, promote code constructs which may lead to less maintainable code.

The foreach loop construct in question may be paraphrased thus:

foreach (1..5) {

    if ( $object->method( "arg$_" ) ) {

        #   ... do stuff

    }

}
[download]

The foreach loop iterates through a range of numbers, specified with either the range operator or a C-style for construct, using this loop index for construction of a parameter name or value through concatenation. That is, there is no use of the loop index as a storage index or reference, the loop using the index only for the creation of string values through concatenation.

This approach, to my mind, is very C-like and, in my humble opinion, could be better performed in the following manner:

foreach ( qw/ arg1 arg2 arg3 arg4 arg5 / ) {

    if ( $object->method( $_ ) ) {

        #   ... do stuff

    }

}
[download]

The difference between these foreach loop constructs is minor from a syntatical standpoint, but for foreach loop constructs where loop indices are being used only for the creation of string values through concatenation, this latter approach is advantageous primarily for reasons of on-going code maintenance.

That is, this latter approach:

• Allows for the reference of all values iterated through within the foreach loop construct in a single code location;
• Allows the addition of other iteration values which may not necessarily meet the value syntax currently employed (for example, iteration values not conforming to the syntax of arg<value>); and,
• Offers slightly improved performance by removing the relatively expensive string concatenation - Note that this statement should be taken with a grain of salt, the performance difference little more than a nano-optimisation (See (tye)Re: Premature optimization from tye).

It is for these first two reasons alone that I would advocate this latter approach to foreach loop constructs to improve the maintainability and usefulness of developed code.

I would welcome your comments and observations.

 

perl -e 'print+unpack("N",pack("B32","00000000000000000000000111001111")),"\n"'

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