Difference between revisions of "Perl vs. PHP"

Revision as of 18:13, 20 October 2006

computing: software: Perl/PHP: Perl vs. PHP

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Overview

Perl and PHP are often compared with each other, largely due to their mutual popularity for web site design. The general consensus seems to be that people use PHP because it was invented specifically for creating web pages, whereas Perl has a lot of other uses as well — or, in other words, people use PHP because they don't know any better, and people who know better use Perl.

Unfortunately, this apparently does nothing to prevent the use of PHP in such heavily-used, highly-developed applications as MediaWiki and Drupal.

Links

PHP in contrast to Perl

Object-Oriented Programming

object-oriented programming, or OOP, was a late addition to both languages, but it's a bit easier to use in PHP. (Perl's implementation may be more powerful, but it's not at all clear how.) A comparison:

characteristic	Perl	PHP
class files	one class per file	multiple classes per file
class initialization code	my $self = {}; $self->{FIELDNAME} = default; ... bless($self); return $self;	$this->fieldname = default;
initialization code within methods	my $self = shift;	none needed
identifier within class code	$self->fieldname	this->$fieldname for per-object data self::$fieldname for static data this->method() for calling method dynamically self::method() for calling method statically

OOP Notes

In class methods, the object itself is an implicit first argument; the shift function uses the @_ magic variable by default, effectively retrieving the object reference.
The Perl bless function causes the package's functions to be bound into the hashref object (probably creates a VMT for it); without being blessed, the object is just a normal hashref.
On the surface, PHP's identifier-within-class syntax seems more complicated, but it made intuitive sense to me (Woozle) except possibly for the issue of which identifiers get dollar-signs and which don't (which is even more complicated in Perl)... although I don't see why PHP needs both "this" and "self" when there's the "->" vs. "::" to disambiguate dynamic from static (but again, this is a minor annoyance and much less confusing than many aspects of Perl's OOP syntax).
In Perl, any string inside delimiters (such as [], {}, ()) is assumed to be a string literal if it does not begin with $ and does not contain any delimiters. (This is a rough guess at the actual rules, which may be more complicated.) For this reason, some examples of class initialization show the field names without quotes, e.g. "$self->{FIELDNAME} = 'value';", which can be more understandably written as "$self->{'FIELDNAME'} = default;".

Notes

PHP::Interpreter: a Perl module for running PHP code, thus making it easier to gracefully port a project from one to the other

@@ Line 33: / Line 33: @@
 |}
 ===OOP Notes===
-* In Perl, it's not quite clear what's going on with the field names. Is FIELDNAME implicitly created as a constant in this context?
+* In class methods, the object itself is an implicit first argument; the {{perlfunc|shift}} function uses the @_ magic variable by default, effectively retrieving the object reference.
+* The Perl {{perlfunc|bless}} function causes the package's functions to be bound into the [[hashref]] object (probably creates a [[virtual method table|VMT]] for it); without being blessed, the object is just a normal hashref.
 * On the surface, PHP's identifier-within-class syntax seems more complicated, but it made intuitive sense to me ({{woozle}}) except possibly for the issue of which identifiers get dollar-signs and which don't (which is even more complicated in Perl)... although I don't see why PHP needs both "this" and "self" when there's the "->" vs. "::" to disambiguate dynamic from static (but again, this is a minor annoyance and much less confusing than many aspects of Perl's OOP syntax).
-* I ''still'' don't understand what {{perlfunc|bless}} does. ({{woozle}}) Or {{perlfunc|shift}}.
+* In Perl, any string inside delimiters (such as [], {}, ()) is assumed to be a string literal if it does not begin with $ and does not contain any delimiters. (This is a rough guess at the actual rules, which may be more complicated.) For this reason, some examples of class initialization show the field names without quotes, e.g. "$self->{FIELDNAME} = 'value';", which can be more understandably written as "$self->{'FIELDNAME'} = default;".
 ==Notes==
 * [http://search.cpan.org/~gschloss/PHP-Interpreter-1.0.1/lib/PHP/Interpreter.pm PHP::Interpreter]: a [[Perl]] module for running [[PHP]] code, thus making it easier to gracefully port a project from one to the other