/usr/share/perl5/vendor_perl
Edit: /usr/share/perl5/vendor_perl/perlglossary.pod (137232B)
=encoding utf8
=head1 NAME
perlglossary - Perl Glossary
=head1 VERSION
version 5.20180605
=head1 DESCRIPTION
A glossary of terms (technical and otherwise) used in the Perl
documentation, derived from the Glossary of I
, Fourth Edition. Words or phrases in bold are defined elsewhere in
this glossary.
Other useful sources include the Unicode Glossary LXmethod> used to
indirectly inspect or update an Bâs state (its B).
=item actual arguments
The BXscalar values> that you supply
to a B or B when you call it. For instance, when you
call C, the string C<"puff"> is the actual argument. See also
B and B.
=item address operator
Some Xlanguages work directly with the memory addresses of
values, but this can be like playing with fire. Perl provides a set of
asbestos gloves for handling all memory management. The closest to an
address operator in Perl is the backslash operator, but it gives you a
B, which is much safer than a memory address.
=item algorithm
A Xwell-defined sequence of steps, explained clearly
enough that even a computer could do them.
=item alias
A Xnickname for something, which behaves in all ways as
though youâd used the original name instead of the nickname. Temporary
aliases are implicitly created in the loop variable for C loops, in
the C<$_> variable for C or C operators, in C<$a> and C<$b>
during Câs comparison function, and in each element of C<@_> for the
B of a subroutine call. Permanent aliases are explicitly
created in B by B symbols or by assignment to
B. Lexically scoped aliases for package variables are explicitly
created by the C declaration.
=item alphabetic
The Xsort of characters we put into words. In Unicode, this
is all letters including all ideographs and certain diacritics, letter
numbers like Roman numerals, and various combining marks.
=item alternatives
A Xlist of possible choices from which you may
select only one, as in, âWould you like door A, B, or C?â Alternatives in
regular expressions are separated with a single vertical bar: C<|>.
Alternatives in normal Perl expressions are separated with a double vertical
bar: C<||>. Logical alternatives in B expressions are separated
with either C<||> or C.
=item anonymous
Used to XXdescribe a B
that is not directly accessible through a named B. Such a referent
must be indirectly accessible through at least one B. When
the last hard reference goes away, the anonymous referent is destroyed
without pity.
=item application
A Xbigger, fancier sort of B with a fancier
name so people donât realize they are using a program.
=item architecture
The kind of Xcomputer youâre working on, where one âkind of
computerâ means all those computers sharing a compatible machine language.
Since Perl programs are (typically) simple text files, not executable
images, a Perl program is much less sensitive to the architecture itâs
running on than programs in other languages, such as C, that are B
into machine code. See also B and B.
=item argument
A Xpiece of data supplied to a B,
B, B, or B to tell it what itâs supposed to
do. Also called a âparameterâ.
=item ARGV
The name of the Xarray containing the B B
from the command line. If you use the empty CE> operator, C
is the name of both the B used to traverse the arguments and the
B containing the name of the current input file.
=item arithmetical operator
A Bsymbol> such as C<+> or C that tells
Perl to do the arithmetic you were supposed to learn in grade school.
=item array
An Xordered sequence of B, stored such that you can
easily access any of the values using an I that specifies
the valueâs B in the sequence.
=item array context
An archaic Xexpression for what is more correctly referred to
as B.
=item Artistic License
The open Xsource license that XLarry Wall
created for Perl, maximizing Perlâs usefulness, availability, and
modifiability. The current version is 2. (L).
=item ASCII
The XXAmerican Standard Code for
Information Interchange (a 7-bit character set adequate only for poorly
representing English text). Often used loosely to describe the lowest 128
values of the various ISO-8859-X character sets, a bunch of mutually
incompatible 8-bit codes best described as half ASCII. See also B.
=item assertion
A XXcomponent of a B that must be true for the pattern to
match but does not necessarily match any characters itself. Often used
specifically to mean a B assertion.
=item assignment
An XB whose assigned mission in life is to
change the value of a B.
=item assignment operator
Either a Xregular B or a compound
B composed of an ordinary assignment and some other operator, that
changes the value of a variable in place; that is, relative to its old
value. For example, C<$a += 2> adds C<2> to C<$a>.
=item associative array
See B. XPlease. The term associative array is the
old Perl 4 term for a B. Some languages call it a dictionary.
=item associativity
Determines Xwhether you do the left B first or the
right B first when you have âA B B B Câ, and
the two operators are of the same precedence. Operators like C<+> are left
associative, while operators like C<**> are right associative. See Camel
chapter 3, âUnary and Binary Operatorsâ for a list of operators and their
associativity.
=item asynchronous
Said of Xevents or activities whose relative
temporal ordering is indeterminate because too many things are going on at
once. Hence, an asynchronous event is one you didnât know when to expect.
=item atom
A Bexpression> component potentially matching a
B containing one or more characters and treated as an indivisible
syntactic unit by any following B. (Contrast with an
B that matches something of B and may not be quantified.)
=item atomic operation
When XDemocritus gave the word âatomâ to the indivisible
bits of matter, he meant literally something that could not be cut: I<áź->
(not) + I<-ĎοΟοĎ> (cuttable). An atomic operation is an action that canât be
interrupted, not one forbidden in a nuclear-free zone.
=item attribute
A new Xfeature that allows the declaration of
B and B with modifiers, as in C. Also another name for an B of an B.
=item autogeneration
A Xfeature of B of B,
whereby the behavior of certain B can be reasonably deduced using
more fundamental operators. This assumes that the overloaded operators will
often have the same relationships as the regular operators. See Camel
chapter 13, âOverloadingâ.
=item autoincrement
To Xadd one to something automatically, hence the name
of the C<++> operator. To instead subtract one from something automatically
is known as an âautodecrementâ.
=item autoload
To Xload on demand. (Also called âlazyâ loading.)
Specifically, to call an C subroutine on behalf of an undefined
subroutine.
=item autosplit
To Xsplit a string automatically, as the I<âa> B
does when running under I<âp> or I<ân> in order to emulate B. (See also
the CX module, which has nothing to do with the
C<âa> switch but a lot to do with autoloading.)
=item autovivification
A XGraeco-Roman word meaning âto bring oneself to lifeâ.
In Perl, storage locations (B) spontaneously generate themselves as
needed, including the creation of any B values to point to
the next level of storage. The assignment C<$a[5][5][5][5][5] = "quintet">
potentially creates five scalar storage locations, plus four references (in
the first four scalar locations) pointing to four new anonymous arrays (to
hold the last four scalar locations). But the point of autovivification is
that you donât have to worry about it.
=item AV
Short XXXfor âarray
valueâ, which refers to one of Perlâs internal data types that holds an
B. The C type is a subclass of B.
=item awk
Descriptive Xediting termâshort for âawkwardâ. Also
coincidentally refers to a venerable text-processing language from which
Perl derived some of its high-level ideas.
=back
=head2 B
=over 4
=item backreference
A XXsubstring B
by a subpattern within unadorned parentheses in a B. Backslashed
decimal numbers (C<\1>, C<\2>, etc.) later in the same pattern refer back to
the corresponding subpattern in the current match. Outside the pattern, the
numbered variables (C<$1>, C<$2>, etc.) continue to refer to these same
values, as long as the pattern was the last successful match of the current
B.
=item backtracking
The Xpractice of saying, âIf I had to do it all over, Iâd do
it differently,â and then actually going back and doing it all over
differently. Mathematically speaking, itâs returning from an unsuccessful
recursion on a tree of possibilities. Perl backtracks when it attempts to
match patterns with a B, and its earlier attempts donât
pan out. See the section âThe Little Engine That /Couldn(nât)â in Camel
chapter 5, âPattern Matchingâ.
=item backward compatibility
Means Xyou can still run your old program
because we didnât break any of the features or bugs it was relying on.
=item bareword
A word Xsufficiently ambiguous to be deemed illegal under
C. In the absence of that stricture, a bareword is
treated as if quotes were around it.
=item base class
A Xgeneric B type; that is, a B
from which other, more specific classes are derived genetically by
B. Also called aXX
âsuperclassâ by people who respect their ancestors.
=item big-endian
From XXSwift: someone who
eats eggs big end first. Also used of computers that store the most
significant B of a word at a lower byte address than the least
significant byte. Often considered superior to little-endian machines. See
also B.
=item binary
Having Xto do with numbers represented in base 2. That means
thereâs basically two numbers: 0 and 1. Also used to describe a file of
ânontextâ, presumably because such a file makes full use of all the binary
bits in its bytes. With the advent of B, this distinction, already
suspect, loses even more of its meaning.
=item binary operator
An Boperator> that takes two B.
=item bind
To Xassign a specific B to a B.
=item bit
An Xinteger in the range from 0 to 1, inclusive. The smallest
possible unit of information storage. An eighth of a B or of a dollar.
(The term âPieces of Eightâ comes from being able to split the old Spanish
dollar into 8 bits, each of which still counted for money. Thatâs why a 25-
cent piece today is still âtwo bitsâ.)
=item bit shift
The Xmovement of bits left or right in a
computer word, which has the effect of multiplying or dividing by a
power of 2.
=item bit string
A Xsequence of B that is actually being thought of as a
sequence of bits, for once.
=item bless
In XXcorporate life, to grant official
approval to a thing, as in, âThe VP of Engineering has blessed our
WebCruncher project.â Similarly, in Perl, to grant official approval to a
B so that it can function as an B, such as a WebCruncher
object. See the C function in Camel chapter 27, âFunctionsâ.
=item block
What Xa B does when it has to wait for something:
âMy process blocked waiting for the disk.â As an unrelated noun, it refers
to a large chunk of data, of a size that the B likes to
deal with (normally a power of 2 such as 512 or 8192). Typically refers to
a chunk of data thatâs coming from or going to a disk file.
=item BLOCK
A XXsyntactic construct
consisting of a sequence of Perl B that is delimited by braces.
The C and C statements are defined in terms of I>s, for
instance. Sometimes we also say âblockâ to mean a lexical scope; that is, a
sequence of statements that acts like a I>, such as within an
C or a file, even though the statements arenât delimited by braces.
=item block buffering
A XXmethod of making input and output
efficient by passing one B at a time. By default, Perl does block
buffering to disk files. See B and B.
=item Boolean
A XXvalue that is either B or
B.
=item Boolean context
A XXspecial kind of B used in conditionals to decide whether the B returned
by an expression is B or B. Does not evaluate as either a
string or a number. See B.
=item breakpoint
A Xspot in your program where youâve told the debugger
to stop B so you can poke around and see whether anything is
wrong yet.
=item broadcast
To Xsend a B to multiple destinations
simultaneously.
=item BSD
A XXpsychoactive drug, popular in the â80s, probably developed at UC
Berkeley or thereabouts. Similar in many ways to the prescription-only
medication called âSystem Vâ, but infinitely more useful. (Or, at least,
more fun.) The full chemical name is âBerkeley Standard Distributionâ.
=item bucket
A Xlocation in a B containing (potentially)
multiple entries whose keys âhashâ to the same hash value according to its
hash function. (As internal policy, you donât have to worry about it unless
youâre into internals, or policy.)
=item buffer
A Xtemporary holding location for data. Data that are
B means that the data is passed on to its destination
whenever the buffer is full. B means that itâs passed on
whenever a complete line is received. B means that itâs
passed every time you do a C command (or equivalent). If your output
is unbuffered, the system processes it one byte at a time without the use of
a holding area. This can be rather inefficient.
=item built-in
A Bfunction> that is predefined in the
language. Even when hidden by B, you can always get at a built-
in function by B its name with the C pseudopackage.
=item bundle
A Xgroup of related modules on B. (Also sometimes
refers to a group of command-line switches grouped into one B.)
=item byte
A Xpiece of data worth eight B in most places.
=item bytecode
A pidgin-like lingo spoken among âdroids when they donât wish to reveal
their orientation (see B). Named after some similar languages spoken
(for similar reasons) between compilers and interpreters in the late 20áľĘ°
century. These languages are characterized by representing everything as a
nonarchitecture-dependent sequence of bytes.
=back
=head2 C
=over 4
=item C
A Xlanguage beloved by many for its inside-out B
definitions, inscrutable B rules, and heavy B of
the function-call mechanism. (Well, actually, people first switched to C
because they found lowercase identifiers easier to read than upper.) Perl is
written in C, so itâs not surprising that Perl borrowed a few ideas from it.
=item cache
A Xdata repository. Instead of computing expensive answers
several times, compute it once and save the result.
=item callback
A Bhandler> that you register with some other part of your
program in the hope that the other part of your program will B your
handler when some event of interest transpires.
=item call by reference
An B-passing XXmechanism in which the B refer directly to the
B, and the B can change the actual arguments
by changing the formal arguments. That is, the formal argument is an
B for the actual argument. See also B.
=item call by value
An Bargument>-passing mechanism in which the B refer to a copy of the B, and the
B cannot change the actual arguments by changing the formal
arguments. See also B.
=item canonical
Reduced Xto a standard form to facilitate comparison.
=item capture variables
The XXvariablesâsuch as C<$1> and
C<$2>, and C<%+> and C<%â >âthat hold the text remembered in a pattern
match. See Camel chapter 5, âPattern Matchingâ.
=item capturing
The XXXuse of parentheses around a B in a
B to store the matched B as a
B. (Captured strings are also returned as a list in B.) See Camel chapter 5, âPattern Matchingâ.
=item cargo cult
Copying Xand pasting code without understanding it, while
superstitiously believing in its value. This term originated from
preindustrial cultures dealing with the detritus of explorers and colonizers
of technologically advanced cultures. See I.
=item case
A XXproperty of certain
characters. Originally, typesetter stored capital letters in the upper of
two cases and small letters in the lower one. Unicode recognizes three
cases: B (B C<\p{lower}>), B
(C<\p{title}>), and B (C<\p{upper}>). A fourth casemapping called
B is not itself a distinct case, but it is used internally to
implement B. Not all letters have case, and some nonletters
have case.
=item casefolding
Comparing Xor matching a string case-insensitively. In Perl, it
is implemented with the C pattern modifier, the C function, and the
C<\F> double-quote translation escape.
=item casemapping
The Xprocess of converting a string to one of the four Unicode
B; in Perl, it is implemented with the C, C