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
139       new [ARGS...]
140           Class method.  Return a new, unattached array handle.  If any argu‐
141           ments are given, they're sent to open().
142
143       open [ARRAYREF]
144           Instance method.  Open the array handle on a new array, pointed to
145           by ARRAYREF.  If no ARRAYREF is given, a "private" array is created
146           to hold the file data.
147
148           Returns the self object on success, undefined on error.
149
150       opened
151           Instance method.  Is the array handle opened on something?
152
153       close
154           Instance method.  Disassociate the array handle from its underlying
155           array.  Done automatically on destroy.
156
157       Input and output
158
159       flush
160           Instance method.  No-op, provided for OO compatibility.
161
162       getc
163           Instance method.  Return the next character, or undef if none
164           remain.  This does a read(1), which is somewhat costly.
165
166       getline
167           Instance method.  Return the next line, or undef on end of data.
168           Can safely be called in an array context.  Currently, lines are
169           delimited by "\n".
170
171       getlines
172           Instance method.  Get all remaining lines.  It will croak() if
173           accidentally called in a scalar context.
174
175       print ARGS...
176           Instance method.  Print ARGS to the underlying array.
177
178           Currently, this always causes a "seek to the end of the array" and
179           generates a new array entry.  This may change in the future.
180
181       read BUF, NBYTES, [OFFSET];
182           Instance method.  Read some bytes from the array.  Returns the num‐
183           ber of bytes actually read, 0 on end-of-file, undef on error.
184
185       write BUF, NBYTES, [OFFSET];
186           Instance method.  Write some bytes into the array.
187
188       Seeking/telling and other attributes
189
190       autoflush
191           Instance method.  No-op, provided for OO compatibility.
192
193       binmode
194           Instance method.  No-op, provided for OO compatibility.
195
196       clearerr
197           Instance method.  Clear the error and EOF flags.  A no-op.
198
199       eof Instance method.  Are we at end of file?
200
201       seek POS,WHENCE
202           Instance method.  Seek to a given position in the stream.  Only a
203           WHENCE of 0 (SEEK_SET) is supported.
204
205       tell
206           Instance method.  Return the current position in the stream, as a
207           numeric offset.
208
209       setpos POS
210           Instance method.  Seek to a given position in the array, using the
211           opaque getpos() value.  Don't expect this to be a number.
212
213       getpos
214           Instance method.  Return the current position in the array, as an
215           opaque value.  Don't expect this to be a number.
216
217       aref
218           Instance method.  Return a reference to the underlying array.
219

WARNINGS

221       Perl's TIEHANDLE spec was incomplete prior to 5.005_57; it was missing
222       support for "seek()", "tell()", and "eof()".  Attempting to use these
223       functions with an IO::ScalarArray will not work prior to 5.005_57.
224       IO::ScalarArray will not have the relevant methods invoked; and even
225       worse, this kind of bug can lie dormant for a while.  If you turn warn‐
226       ings on (via $^W or "perl -w"), and you see something like this...
227
228           attempt to seek on unopened filehandle
229
230       ...then you are probably trying to use one of these functions on an
231       IO::ScalarArray with an old Perl.  The remedy is to simply use the OO
232       version; e.g.:
233
234           $AH->seek(0,0);    ### GOOD: will work on any 5.005
235           seek($AH,0,0);     ### WARNING: will only work on 5.005_57 and beyond
236

VERSION

238       $Id: ScalarArray.pm,v 1.7 2005/02/10 21:21:53 dfs Exp $
239

AUTHOR

241       Primary Maintainer
242
243       David F. Skoll (dfs@roaringpenguin.com).
244
245       Principal author
246
247       Eryq (eryq@zeegee.com).  President, ZeeGee Software Inc
248       (http://www.zeegee.com).
249
250       Other contributors
251
252       Thanks to the following individuals for their invaluable contributions
253       (if I've forgotten or misspelled your name, please email me!):
254
255       Andy Glew, for suggesting "getc()".
256
257       Brandon Browning, for suggesting "opened()".
258
259       Eric L. Brine, for his offset-using read() and write() implementations.
260
261       Doug Wilson, for the IO::Handle inheritance and automatic tie-ing.
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265perl v5.8.8                       2005-02-10                IO::ScalarArray(3)