Perl in a Nutshell phần 6 ppsx

Chapter 8 Standard Modules8.65 Fatal Provides a way to replace functions that return false on failure with equivalents that die instead, so youcan use the functions without having to tes

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Chapter 8 Standard Modules

8.64 ExtUtils::testlib

Used for testing a module after it's been built and before it's been installed, when you don't want to (or

can't) run make test Adding:

use ExtUtils::testlib;

to your test program causes the intermediate directories used by make to be added to @INC, allowing you

to run the test

Programming | Perl Cookbook ]

[Chapter 8] 8.64 ExtUtils::testlib

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8.65 Fatal

Provides a way to replace functions that return false on failure with equivalents that die instead, so youcan use the functions without having to test the return values explicitly Fatal reports errors via die; youcan trap them with $SIG{ DIE } if you want to take some action before the program exits You canuse Fatal for both user-defined functions and Perl core operators except exec and system

import

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[Chapter 8] 8.65 Fatal

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8.66 Fcntl

A translation of the C fcntl.h program that uses h2xs (which builds a Perl extension from a C header file)

and the C compiler to translate #define symbols and make them available as functions Exports thefollowing routines by default; each routine returns the value of the #define that is the same as theroutine name:

FD_CLOEXEC F_DUPFD F_GETFD F_GETFL F_GETLK

F_RDLCK F_SETFD F_SETFL F_SETLK F_SETLKW

F_UNLCK F_WRLCK O_APPEND O_CREAT O_EXCL

O_NDELAY O_NOCTTY O_NONBLOCK O_RDONLY O_RDWR

O_TRUNC O_WRONLY

[Chapter 8] 8.66 Fcntl

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8.67 fields

Pragma that provides the ability to define class fields at compile time, by updating the %FIELDS hash inthe calling package The %FIELDS hash is set up at compile time as well; use the base pragma to copyfields from base classes, and then fields to add new fields Lets you have objects with named fields

that are as compact and fast as arrays to access For more details, see the fields manpage and the

pseudo-hash section of the perlref manpage.

[Chapter 8] 8.67 fields

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8.68 File::Basename

Parses a file's path, returning its three component pieces: the path to the file, the file's basename, and thefile's extension For example, for:

/usr/local/lib/perl5/SelectSaver.pm

the path is /usr/local/lib/perl5, the basename is SelectSaver, and the extension is pm File::Basename

exports the following functions:

[Chapter 8] 8.68 File::Basename

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8.69 File::CheckTree

Runs file tests on a set of files Exports one function, validate, which takes a single multi-line string

as input Each line of the string contains a filename plus a test to run on the file The test can be followedwith || die to make it a fatal error if it fails The default is || warn Prepending ! to the test

reverses the sense of the test You can group tests (e.g., -rwx); only the first failed test of the groupproduces a warning For example:

Available tests include all the standard Perl file-test operators except -t, -M, -A, and -C Unless it dies,

validate returns the number of warnings issued

[Chapter 8] 8.69 File::CheckTree

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[Chapter 8] 8.71 File::Copy

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8.72 File::DosGlob

Provides a portable enhanced DOS-like globbing for the standard Perl distribution DosGlob lets you usewildcards in directory paths, is case-insensitive, and accepts both backslashes and forward slashes

(although you may have to double the backslashes) Can be run three ways:

From a Perl script:

require 5.004use File::DosGlob 'glob';

@perlfiles = glob " \pe?l/*.p?";

print < \pe?l/*.p?>;

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With the perl command, on the command line:

# from the command line (overrides only in main::)

% perl -MFile::DosGlob=glob -e "print < /pe*/*p?>"

[Chapter 8] 8.72 File::DosGlob

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8.75 File::Spec

Performs common operations on file specifications in a portable way To do that, it automatically loadsthe appropriate operating-system-specific module, which is one of File::Spec::Mac, File::Spec::OS2,File::Spec::Unix, File::Spec::VMS, or File::Spec::Win32 The complete reference of available functions

is given in File::Spec::Unix; the functions are inherited by the other modules and overridden as

necessary Subroutines should be called as class methods, rather than directly

[Chapter 8] 8.75 File::Spec

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8.77 File::Spec::OS2

File::Spec for OS/2 Overrides the implementation of the File::Spec::Unix methods, but not the interface

[Chapter 8] 8.77 File::Spec::OS2

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[Chapter 8] 8.79 File::Spec::VMS

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nlink Number of links to the file

atime Last access time

mtime Last modified time

ctime Inode change time

blksize Preferred blocksize for filesystem I/O

blocks Number of blocks allocated

You can access the status fields either with the methods or by importing the fields into your namespacewith the :FIELDS import tag and then accessing them by prepending st_ to the field name (e.g.,

$st_mode) Here are examples of doing it both ways:

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The following additional FileHandle methods act as front-ends for the corresponding built-in Perl

functions (see the O'Reilly book Programming Perl or the perlfunc manpage for more detail):

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Finally, the following methods are useful:

Works like Perl's <FILEHANDLE> construct, except that it can be safely called in an array

context (but it still returns just one line)

$fh->getlines

Works like Perl's <FILEHANDLE> construct when called in an array context to read all remaininglines in a file

[Chapter 8] 8.83 FileHandle

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8.84 FindBin

Finds the full path to a script's bin directory, letting you use relative paths to that directory without

needing to know the actual location:

use FindBin;

use lib "$FindBin::Bin/ /lib";

or:

use FindBin qw($Bin);

use lib "$Bin/ /lib";

FindBin exports the following variables:

$Script with all links resolved

If you invoke Perl with the -e option or read the Perl script from STDIN, then FindBin sets both $Bin

and $RealBin to the current directory

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8.85 GDBM_File

Allows Perl programs to make use of the facilities provided by the GNU gdbm library Most of the

libgdbm.a functions are available as methods of the GDBM_File interface See the gdbm(3) manpage and

the description of DB_File in this chapter The following is an example of the use of GDBM_File:

use GDBM_File;

tie %hash, "GDBM_File", $filename, &GDBM_WRCREAT, 0644);

# read/writes of %hash are now read/writes of $filename

untie %hash;

[Chapter 8] 8.85 GDBM_File

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8.86 Getopt::Long

Lets your program accept command-line options with long names, introduced by Standard

single-character options are also accepted Options that start with may have an argument appended,following a space or an equals sign (=):

[Chapter 8] 8.86 Getopt::Long

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8.87 Getopt::Std

Processes single-character command-line options with option clustering Exports two functions, whichanalyze @ARGV, extract information about the options, and return this information to your program in aset of variables Processing of @ARGV stops when an argument without a leading - is encountered, if thatargument is not associated with a preceding option Otherwise, @ARGV is processed to the end and leftempty

[Chapter 8] 8.87 Getopt::Std

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8.88 I18N::Collate

The use of I18N::Collate is now deprecated, although it is still provided for compatibility with olderprograms Don't use it in new programs, as its functionality was integrated into the core Perl in Perl5.004 See the locale pragma

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8.90 IO

Loads all of the following IO modules with a single use statement: IO::Handle, IO::Seekable, IO::File,IO::Pipe, and IO::Socket

[Chapter 8] 8.90 IO

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Method Description

close Closes file or pipe

eof Returns 1 if next read will return end-of-file

fileno Returns file descriptor for a filehandle

print Prints a string or comma-separated list of strings

printf Prints a formatted string

[Chapter 8] 8.92 IO::Handle

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read Reads data from a filehandle

stat Returns an array of status information for a file

sysread Reads data from a filehandle with system call read(2)

syswrite Writes data to a filehandle with system call write(2)

truncate Truncates a file to a specified length

Finally, the following methods act on the equivalent Perl variables See Chapter 4 for more information

Method Description

autoflush If nonzero, forces a flush now and after each write or print

(default 0)

format_page_number Current page number

format_lines_per_page Current page length (default 60)

format_lines_left Number of lines left on page

format_name Name of current report format

format_top_name Name of current top-of-page format

format_line_break_characters Current set of linebreak chars for a format

format_formfeed Formfeed char used by formats (default \f)

format_write Wrapper for write function

input_record_separator Input record separator (default newline)

input_line_number Current input line number for last filehandle accessed

output_field_separator Output field separator for print

output_record_separator Output record separator for print

[Chapter 8] 8.92 IO::Handle

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[Chapter 8] 8.94 IO::Seekable

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[Chapter 8] 8.96 IO::Socket

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[Chapter 8] 8.98 IPC::Open2

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8.99 IPC::Open3

IPC::Open3 works like IPC::Open2

use IPC::Open3;

$pid = open3($wtr, $rdr, $err, $cmd_with_args);

$pid = open3($wtr, $rdr, $err, $cmd, "arg1", "arg2", );

The following differences apply:

The first two arguments ($wtr and $rdr) are passed in the opposite order

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A third filehandle can be passed, for standard error If this argument is given as "", then STDERRand STDOUT for $cmd are on the same filehandle

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If $wtr begins with <, then the leading < is stripped from the name and the remainder is assumed

to be a regular filehandle for an open file, rather than a reference to a typeglob open3 opens thisfile as STDIN for $cmd and closes it in the parent Likewise, if $rdr or $err begins with >,then $cmd directs STDOUT or STDERR directly to that file rather than to the parent

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[Chapter 8] 8.99 IPC::Open3

Tiêu đề	Perl in a Nutshell
Trường học	University of Crypto
Chuyên ngành	Computer Science
Thể loại	Tài liệu
Năm xuất bản	2001
Thành phố	Crypto

Định dạng
Số trang	72
Dung lượng	6,46 MB