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Perl 5.6.1 and newer support autovivification of file and directory handles. [3] Calling open() on an undefined variable will set it to a filehandle. According to perl561delta, "[t]his largely eliminates the need for typeglobs when opening filehandles that must be passed around, as in the following example:
POE, The Perl Object Environment can be thought of as a tiny modular operating system. One or more POE programs or instances can be run concurrently and are generally well suited for cooperative multitasking. The POE package consists of namespaces and abstractions that guide future development of POE in an open-ended CPAN-style convention.
Originally, filehandles could only be created with package variables, using the ALL_CAPS convention to distinguish it from other variables. Perl 5.6 and newer also accept a scalar variable, which will be set (autovivified) to a reference to an anonymous filehandle, in place of a named filehandle.
The Perl virtual machine is a stack-based process virtual machine implemented as an opcodes interpreter which runs previously compiled programs written in the Perl language. The opcodes interpreter is a part of the Perl interpreter, which also contains a compiler (lexer, parser and optimizer) in one executable file, commonly /usr/bin/perl on various Unix-like systems or perl.exe on Microsoft ...
An environment variable is a user-definable value that can affect the way running processes will behave on a computer. Environment variables are part of the ...
For entities such as variables, scope is a subset of lifetime (also known as extent)—a name can only refer to a variable that exists (possibly with undefined value), but variables that exist are not necessarily visible: a variable may exist but be inaccessible (the value is stored but not referred to within a given context), or accessible but ...
Diagram of the mechanism of using perl modules. A Perl module is a discrete component of software for the Perl programming language.Technically, it is a particular set of conventions for using Perl's package mechanism that has become universally adopted.
The concept behind taint checking is that any variable that can be modified by an outside user (for example a variable set by a field in a web form) poses a potential security risk. If that variable is used in an expression that sets a second variable, that second variable is now also suspicious. The taint checking tool can then proceed ...