1IO::ScalarArray(3)    User Contributed Perl Documentation   IO::ScalarArray(3)
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NAME

6       IO::ScalarArray - IO:: interface for reading/writing an array of
7       scalars
8

SYNOPSIS

10       Perform I/O on strings, using the basic OO interface...
11
12           use IO::ScalarArray;
13           @data = ("My mes", "sage:\n");
14
15           ### Open a handle on an array, and append to it:
16           $AH = new IO::ScalarArray \@data;
17           $AH->print("Hello");
18           $AH->print(", world!\nBye now!\n");
19           print "The array is now: ", @data, "\n";
20
21           ### Open a handle on an array, read it line-by-line, then close it:
22           $AH = new IO::ScalarArray \@data;
23           while (defined($_ = $AH->getline)) {
24               print "Got line: $_";
25           }
26           $AH->close;
27
28           ### Open a handle on an array, and slurp in all the lines:
29           $AH = new IO::ScalarArray \@data;
30           print "All lines:\n", $AH->getlines;
31
32           ### Get the current position (either of two ways):
33           $pos = $AH->getpos;
34           $offset = $AH->tell;
35
36           ### Set the current position (either of two ways):
37           $AH->setpos($pos);
38           $AH->seek($offset, 0);
39
40           ### Open an anonymous temporary array:
41           $AH = new IO::ScalarArray;
42           $AH->print("Hi there!");
43           print "I printed: ", @{$AH->aref}, "\n";      ### get at value
44
45       Don't like OO for your I/O?  No problem.  Thanks to the magic of an
46       invisible tie(), the following now works out of the box, just as it
47       does with IO::Handle:
48
49           use IO::ScalarArray;
50           @data = ("My mes", "sage:\n");
51
52           ### Open a handle on an array, and append to it:
53           $AH = new IO::ScalarArray \@data;
54           print $AH "Hello";
55           print $AH ", world!\nBye now!\n";
56           print "The array is now: ", @data, "\n";
57
58           ### Open a handle on a string, read it line-by-line, then close it:
59           $AH = new IO::ScalarArray \@data;
60           while (<$AH>) {
61               print "Got line: $_";
62           }
63           close $AH;
64
65           ### Open a handle on a string, and slurp in all the lines:
66           $AH = new IO::ScalarArray \@data;
67           print "All lines:\n", <$AH>;
68
69           ### Get the current position (WARNING: requires 5.6):
70           $offset = tell $AH;
71
72           ### Set the current position (WARNING: requires 5.6):
73           seek $AH, $offset, 0;
74
75           ### Open an anonymous temporary scalar:
76           $AH = new IO::ScalarArray;
77           print $AH "Hi there!";
78           print "I printed: ", @{$AH->aref}, "\n";      ### get at value
79
80       And for you folks with 1.x code out there: the old tie() style still
81       works, though this is unnecessary and deprecated:
82
83           use IO::ScalarArray;
84
85           ### Writing to a scalar...
86           my @a;
87           tie *OUT, 'IO::ScalarArray', \@a;
88           print OUT "line 1\nline 2\n", "line 3\n";
89           print "Array is now: ", @a, "\n"
90
91           ### Reading and writing an anonymous scalar...
92           tie *OUT, 'IO::ScalarArray';
93           print OUT "line 1\nline 2\n", "line 3\n";
94           tied(OUT)->seek(0,0);
95           while (<OUT>) {
96               print "Got line: ", $_;
97           }
98

DESCRIPTION

100       This class is part of the IO::Stringy distribution; see IO::Stringy for
101       change log and general information.
102
103       The IO::ScalarArray class implements objects which behave just like
104       IO::Handle (or FileHandle) objects, except that you may use them to
105       write to (or read from) arrays of scalars.  Logically, an array of
106       scalars defines an in-core "file" whose contents are the concatenation
107       of the scalars in the array.  The handles created by this class are
108       automatically tiehandle'd (though please see "WARNINGS" for information
109       relevant to your Perl version).
110
111       For writing large amounts of data with individual print() statements,
112       this class is likely to be more efficient than IO::Scalar.
113
114       Basically, this:
115
116           my @a;
117           $AH = new IO::ScalarArray \@a;
118           $AH->print("Hel", "lo, ");         ### OO style
119           $AH->print("world!\n");            ### ditto
120
121       Or this:
122
123           my @a;
124           $AH = new IO::ScalarArray \@a;
125           print $AH "Hel", "lo, ";           ### non-OO style
126           print $AH "world!\n";              ### ditto
127
128       Causes @a to be set to the following array of 3 strings:
129
130           ( "Hel" ,
131             "lo, " ,
132             "world!\n" )
133
134       See IO::Scalar and compare with this class.
135

PUBLIC INTERFACE

137   Construction
138       new [ARGS...]
139           Class method.  Return a new, unattached array handle.  If any
140           arguments are given, they're sent to open().
141
142       open [ARRAYREF]
143           Instance method.  Open the array handle on a new array, pointed to
144           by ARRAYREF.  If no ARRAYREF is given, a "private" array is created
145           to hold the file data.
146
147           Returns the self object on success, undefined on error.
148
149       opened
150           Instance method.  Is the array handle opened on something?
151
152       close
153           Instance method.  Disassociate the array handle from its underlying
154           array.  Done automatically on destroy.
155
156   Input and output
157       flush
158           Instance method.  No-op, provided for OO compatibility.
159
160       getc
161           Instance method.  Return the next character, or undef if none
162           remain.  This does a read(1), which is somewhat costly.
163
164       getline
165           Instance method.  Return the next line, or undef on end of data.
166           Can safely be called in an array context.  Currently, lines are
167           delimited by "\n".
168
169       getlines
170           Instance method.  Get all remaining lines.  It will croak() if
171           accidentally called in a scalar context.
172
173       print ARGS...
174           Instance method.  Print ARGS to the underlying array.
175
176           Currently, this always causes a "seek to the end of the array" and
177           generates a new array entry.  This may change in the future.
178
179       read BUF, NBYTES, [OFFSET];
180           Instance method.  Read some bytes from the array.  Returns the
181           number of bytes actually read, 0 on end-of-file, undef on error.
182
183       write BUF, NBYTES, [OFFSET];
184           Instance method.  Write some bytes into the array.
185
186   Seeking/telling and other attributes
187       autoflush
188           Instance method.  No-op, provided for OO compatibility.
189
190       binmode
191           Instance method.  No-op, provided for OO compatibility.
192
193       clearerr
194           Instance method.  Clear the error and EOF flags.  A no-op.
195
196       eof Instance method.  Are we at end of file?
197
198       seek POS,WHENCE
199           Instance method.  Seek to a given position in the stream.  Only a
200           WHENCE of 0 (SEEK_SET) is supported.
201
202       tell
203           Instance method.  Return the current position in the stream, as a
204           numeric offset.
205
206       setpos POS
207           Instance method.  Seek to a given position in the array, using the
208           opaque getpos() value.  Don't expect this to be a number.
209
210       getpos
211           Instance method.  Return the current position in the array, as an
212           opaque value.  Don't expect this to be a number.
213
214       aref
215           Instance method.  Return a reference to the underlying array.
216

WARNINGS

218       Perl's TIEHANDLE spec was incomplete prior to 5.005_57; it was missing
219       support for "seek()", "tell()", and "eof()".  Attempting to use these
220       functions with an IO::ScalarArray will not work prior to 5.005_57.
221       IO::ScalarArray will not have the relevant methods invoked; and even
222       worse, this kind of bug can lie dormant for a while.  If you turn
223       warnings on (via $^W or "perl -w"), and you see something like this...
224
225           attempt to seek on unopened filehandle
226
227       ...then you are probably trying to use one of these functions on an
228       IO::ScalarArray with an old Perl.  The remedy is to simply use the OO
229       version; e.g.:
230
231           $AH->seek(0,0);    ### GOOD: will work on any 5.005
232           seek($AH,0,0);     ### WARNING: will only work on 5.005_57 and beyond
233

VERSION

235       $Id: ScalarArray.pm,v 1.7 2005/02/10 21:21:53 dfs Exp $
236

AUTHOR

238   Primary Maintainer
239       David F. Skoll (dfs@roaringpenguin.com).
240
241   Principal author
242       Eryq (eryq@zeegee.com).  President, ZeeGee Software Inc
243       (http://www.zeegee.com).
244
245   Other contributors
246       Thanks to the following individuals for their invaluable contributions
247       (if I've forgotten or misspelled your name, please email me!):
248
249       Andy Glew, for suggesting "getc()".
250
251       Brandon Browning, for suggesting "opened()".
252
253       Eric L. Brine, for his offset-using read() and write() implementations.
254
255       Doug Wilson, for the IO::Handle inheritance and automatic tie-ing.
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259perl v5.16.3                      2005-02-10                IO::ScalarArray(3)
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