| 1 | .\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32 |
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| 25 | .. |
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| 32 | .tr \(*W-|\(bv\*(Tr |
| 33 | .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' |
| 34 | .ie n \{\ |
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| 37 | . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch |
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| 50 | .\" |
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| 52 | .\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index |
| 53 | .\" entries marked with X<> in POD. Of course, you'll have to process the |
| 54 | .\" output yourself in some meaningful fashion. |
| 55 | .if \nF \{\ |
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| 98 | . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' |
| 99 | . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' |
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| 103 | .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' |
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| 115 | . \" for low resolution devices (crt and lpr) |
| 116 | .if \n(.H>23 .if \n(.V>19 \ |
| 117 | \{\ |
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| 127 | .\} |
| 128 | .rm #[ #] #H #V #F C |
| 129 | .\" ======================================================================== |
| 130 | .\" |
| 131 | .IX Title "Data::Dumper 3" |
| 132 | .TH Data::Dumper 3 "2001-09-21" "perl v5.8.8" "Perl Programmers Reference Guide" |
| 133 | .SH "NAME" |
| 134 | Data::Dumper \- stringified perl data structures, suitable for both printing and \f(CW\*(C`eval\*(C'\fR |
| 135 | .SH "SYNOPSIS" |
| 136 | .IX Header "SYNOPSIS" |
| 137 | .Vb 1 |
| 138 | \& use Data::Dumper; |
| 139 | .Ve |
| 140 | .PP |
| 141 | .Vb 2 |
| 142 | \& # simple procedural interface |
| 143 | \& print Dumper($foo, $bar); |
| 144 | .Ve |
| 145 | .PP |
| 146 | .Vb 2 |
| 147 | \& # extended usage with names |
| 148 | \& print Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]); |
| 149 | .Ve |
| 150 | .PP |
| 151 | .Vb 5 |
| 152 | \& # configuration variables |
| 153 | \& { |
| 154 | \& local $Data::Dumper::Purity = 1; |
| 155 | \& eval Data::Dumper->Dump([$foo, $bar], [qw(foo *ary)]); |
| 156 | \& } |
| 157 | .Ve |
| 158 | .PP |
| 159 | .Vb 7 |
| 160 | \& # OO usage |
| 161 | \& $d = Data::Dumper->new([$foo, $bar], [qw(foo *ary)]); |
| 162 | \& ... |
| 163 | \& print $d->Dump; |
| 164 | \& ... |
| 165 | \& $d->Purity(1)->Terse(1)->Deepcopy(1); |
| 166 | \& eval $d->Dump; |
| 167 | .Ve |
| 168 | .SH "DESCRIPTION" |
| 169 | .IX Header "DESCRIPTION" |
| 170 | Given a list of scalars or reference variables, writes out their contents in |
| 171 | perl syntax. The references can also be objects. The contents of each |
| 172 | variable is output in a single Perl statement. Handles self-referential |
| 173 | structures correctly. |
| 174 | .PP |
| 175 | The return value can be \f(CW\*(C`eval\*(C'\fRed to get back an identical copy of the |
| 176 | original reference structure. |
| 177 | .PP |
| 178 | Any references that are the same as one of those passed in will be named |
| 179 | \&\f(CW$VAR\fR\fIn\fR (where \fIn\fR is a numeric suffix), and other duplicate references |
| 180 | to substructures within \f(CW$VAR\fR\fIn\fR will be appropriately labeled using arrow |
| 181 | notation. You can specify names for individual values to be dumped if you |
| 182 | use the \f(CW\*(C`Dump()\*(C'\fR method, or you can change the default \f(CW$VAR\fR prefix to |
| 183 | something else. See \f(CW$Data::Dumper::Varname\fR and \f(CW$Data::Dumper::Terse\fR |
| 184 | below. |
| 185 | .PP |
| 186 | The default output of self-referential structures can be \f(CW\*(C`eval\*(C'\fRed, but the |
| 187 | nested references to \f(CW$VAR\fR\fIn\fR will be undefined, since a recursive |
| 188 | structure cannot be constructed using one Perl statement. You should set the |
| 189 | \&\f(CW\*(C`Purity\*(C'\fR flag to 1 to get additional statements that will correctly fill in |
| 190 | these references. Moreover, if \f(CW\*(C`eval\*(C'\fRed when strictures are in effect, |
| 191 | you need to ensure that any variables it accesses are previously declared. |
| 192 | .PP |
| 193 | In the extended usage form, the references to be dumped can be given |
| 194 | user-specified names. If a name begins with a \f(CW\*(C`*\*(C'\fR, the output will |
| 195 | describe the dereferenced type of the supplied reference for hashes and |
| 196 | arrays, and coderefs. Output of names will be avoided where possible if |
| 197 | the \f(CW\*(C`Terse\*(C'\fR flag is set. |
| 198 | .PP |
| 199 | In many cases, methods that are used to set the internal state of the |
| 200 | object will return the object itself, so method calls can be conveniently |
| 201 | chained together. |
| 202 | .PP |
| 203 | Several styles of output are possible, all controlled by setting |
| 204 | the \f(CW\*(C`Indent\*(C'\fR flag. See \*(L"Configuration Variables or Methods\*(R" below |
| 205 | for details. |
| 206 | .Sh "Methods" |
| 207 | .IX Subsection "Methods" |
| 208 | .IP "\fI\s-1PACKAGE\s0\fR\->new(\fI\s-1ARRAYREF\s0 [\fR, \fI\s-1ARRAYREF\s0]\fR)" 4 |
| 209 | .IX Item "PACKAGE->new(ARRAYREF [, ARRAYREF])" |
| 210 | Returns a newly created \f(CW\*(C`Data::Dumper\*(C'\fR object. The first argument is an |
| 211 | anonymous array of values to be dumped. The optional second argument is an |
| 212 | anonymous array of names for the values. The names need not have a leading |
| 213 | \&\f(CW\*(C`$\*(C'\fR sign, and must be comprised of alphanumeric characters. You can begin |
| 214 | a name with a \f(CW\*(C`*\*(C'\fR to specify that the dereferenced type must be dumped |
| 215 | instead of the reference itself, for \s-1ARRAY\s0 and \s-1HASH\s0 references. |
| 216 | .Sp |
| 217 | The prefix specified by \f(CW$Data::Dumper::Varname\fR will be used with a |
| 218 | numeric suffix if the name for a value is undefined. |
| 219 | .Sp |
| 220 | Data::Dumper will catalog all references encountered while dumping the |
| 221 | values. Cross-references (in the form of names of substructures in perl |
| 222 | syntax) will be inserted at all possible points, preserving any structural |
| 223 | interdependencies in the original set of values. Structure traversal is |
| 224 | depth\-first, and proceeds in order from the first supplied value to |
| 225 | the last. |
| 226 | .IP "\fI$OBJ\fR\->Dump \fIor\fR \fI\s-1PACKAGE\s0\fR\->Dump(\fI\s-1ARRAYREF\s0 [\fR, \fI\s-1ARRAYREF\s0]\fR)" 4 |
| 227 | .IX Item "$OBJ->Dump or PACKAGE->Dump(ARRAYREF [, ARRAYREF])" |
| 228 | Returns the stringified form of the values stored in the object (preserving |
| 229 | the order in which they were supplied to \f(CW\*(C`new\*(C'\fR), subject to the |
| 230 | configuration options below. In a list context, it returns a list |
| 231 | of strings corresponding to the supplied values. |
| 232 | .Sp |
| 233 | The second form, for convenience, simply calls the \f(CW\*(C`new\*(C'\fR method on its |
| 234 | arguments before dumping the object immediately. |
| 235 | .IP "\fI$OBJ\fR\->Seen(\fI[\s-1HASHREF\s0]\fR)" 4 |
| 236 | .IX Item "$OBJ->Seen([HASHREF])" |
| 237 | Queries or adds to the internal table of already encountered references. |
| 238 | You must use \f(CW\*(C`Reset\*(C'\fR to explicitly clear the table if needed. Such |
| 239 | references are not dumped; instead, their names are inserted wherever they |
| 240 | are encountered subsequently. This is useful especially for properly |
| 241 | dumping subroutine references. |
| 242 | .Sp |
| 243 | Expects an anonymous hash of name => value pairs. Same rules apply for names |
| 244 | as in \f(CW\*(C`new\*(C'\fR. If no argument is supplied, will return the \*(L"seen\*(R" list of |
| 245 | name => value pairs, in a list context. Otherwise, returns the object |
| 246 | itself. |
| 247 | .IP "\fI$OBJ\fR\->Values(\fI[\s-1ARRAYREF\s0]\fR)" 4 |
| 248 | .IX Item "$OBJ->Values([ARRAYREF])" |
| 249 | Queries or replaces the internal array of values that will be dumped. |
| 250 | When called without arguments, returns the values. Otherwise, returns the |
| 251 | object itself. |
| 252 | .IP "\fI$OBJ\fR\->Names(\fI[\s-1ARRAYREF\s0]\fR)" 4 |
| 253 | .IX Item "$OBJ->Names([ARRAYREF])" |
| 254 | Queries or replaces the internal array of user supplied names for the values |
| 255 | that will be dumped. When called without arguments, returns the names. |
| 256 | Otherwise, returns the object itself. |
| 257 | .IP "\fI$OBJ\fR\->Reset" 4 |
| 258 | .IX Item "$OBJ->Reset" |
| 259 | Clears the internal table of \*(L"seen\*(R" references and returns the object |
| 260 | itself. |
| 261 | .Sh "Functions" |
| 262 | .IX Subsection "Functions" |
| 263 | .IP "Dumper(\fI\s-1LIST\s0\fR)" 4 |
| 264 | .IX Item "Dumper(LIST)" |
| 265 | Returns the stringified form of the values in the list, subject to the |
| 266 | configuration options below. The values will be named \f(CW$VAR\fR\fIn\fR in the |
| 267 | output, where \fIn\fR is a numeric suffix. Will return a list of strings |
| 268 | in a list context. |
| 269 | .Sh "Configuration Variables or Methods" |
| 270 | .IX Subsection "Configuration Variables or Methods" |
| 271 | Several configuration variables can be used to control the kind of output |
| 272 | generated when using the procedural interface. These variables are usually |
| 273 | \&\f(CW\*(C`local\*(C'\fRized in a block so that other parts of the code are not affected by |
| 274 | the change. |
| 275 | .PP |
| 276 | These variables determine the default state of the object created by calling |
| 277 | the \f(CW\*(C`new\*(C'\fR method, but cannot be used to alter the state of the object |
| 278 | thereafter. The equivalent method names should be used instead to query |
| 279 | or set the internal state of the object. |
| 280 | .PP |
| 281 | The method forms return the object itself when called with arguments, |
| 282 | so that they can be chained together nicely. |
| 283 | .IP "\(bu" 4 |
| 284 | $Data::Dumper::Indent \fIor\fR \fI$OBJ\fR\->Indent(\fI[\s-1NEWVAL\s0]\fR) |
| 285 | .Sp |
| 286 | Controls the style of indentation. It can be set to 0, 1, 2 or 3. Style 0 |
| 287 | spews output without any newlines, indentation, or spaces between list |
| 288 | items. It is the most compact format possible that can still be called |
| 289 | valid perl. Style 1 outputs a readable form with newlines but no fancy |
| 290 | indentation (each level in the structure is simply indented by a fixed |
| 291 | amount of whitespace). Style 2 (the default) outputs a very readable form |
| 292 | which takes into account the length of hash keys (so the hash value lines |
| 293 | up). Style 3 is like style 2, but also annotates the elements of arrays |
| 294 | with their index (but the comment is on its own line, so array output |
| 295 | consumes twice the number of lines). Style 2 is the default. |
| 296 | .IP "\(bu" 4 |
| 297 | $Data::Dumper::Purity \fIor\fR \fI$OBJ\fR\->Purity(\fI[\s-1NEWVAL\s0]\fR) |
| 298 | .Sp |
| 299 | Controls the degree to which the output can be \f(CW\*(C`eval\*(C'\fRed to recreate the |
| 300 | supplied reference structures. Setting it to 1 will output additional perl |
| 301 | statements that will correctly recreate nested references. The default is |
| 302 | 0. |
| 303 | .IP "\(bu" 4 |
| 304 | $Data::Dumper::Pad \fIor\fR \fI$OBJ\fR\->Pad(\fI[\s-1NEWVAL\s0]\fR) |
| 305 | .Sp |
| 306 | Specifies the string that will be prefixed to every line of the output. |
| 307 | Empty string by default. |
| 308 | .IP "\(bu" 4 |
| 309 | $Data::Dumper::Varname \fIor\fR \fI$OBJ\fR\->Varname(\fI[\s-1NEWVAL\s0]\fR) |
| 310 | .Sp |
| 311 | Contains the prefix to use for tagging variable names in the output. The |
| 312 | default is \*(L"\s-1VAR\s0\*(R". |
| 313 | .IP "\(bu" 4 |
| 314 | $Data::Dumper::Useqq \fIor\fR \fI$OBJ\fR\->Useqq(\fI[\s-1NEWVAL\s0]\fR) |
| 315 | .Sp |
| 316 | When set, enables the use of double quotes for representing string values. |
| 317 | Whitespace other than space will be represented as \f(CW\*(C`[\en\et\er]\*(C'\fR, \*(L"unsafe\*(R" |
| 318 | characters will be backslashed, and unprintable characters will be output as |
| 319 | quoted octal integers. Since setting this variable imposes a performance |
| 320 | penalty, the default is 0. \f(CW\*(C`Dump()\*(C'\fR will run slower if this flag is set, |
| 321 | since the fast \s-1XSUB\s0 implementation doesn't support it yet. |
| 322 | .IP "\(bu" 4 |
| 323 | $Data::Dumper::Terse \fIor\fR \fI$OBJ\fR\->Terse(\fI[\s-1NEWVAL\s0]\fR) |
| 324 | .Sp |
| 325 | When set, Data::Dumper will emit single, non-self-referential values as |
| 326 | atoms/terms rather than statements. This means that the \f(CW$VAR\fR\fIn\fR names |
| 327 | will be avoided where possible, but be advised that such output may not |
| 328 | always be parseable by \f(CW\*(C`eval\*(C'\fR. |
| 329 | .IP "\(bu" 4 |
| 330 | $Data::Dumper::Freezer \fIor\fR $\fI\s-1OBJ\s0\fR\->Freezer(\fI[\s-1NEWVAL\s0]\fR) |
| 331 | .Sp |
| 332 | Can be set to a method name, or to an empty string to disable the feature. |
| 333 | Data::Dumper will invoke that method via the object before attempting to |
| 334 | stringify it. This method can alter the contents of the object (if, for |
| 335 | instance, it contains data allocated from C), and even rebless it in a |
| 336 | different package. The client is responsible for making sure the specified |
| 337 | method can be called via the object, and that the object ends up containing |
| 338 | only perl data types after the method has been called. Defaults to an empty |
| 339 | string. |
| 340 | .Sp |
| 341 | If an object does not support the method specified (determined using |
| 342 | \&\fIUNIVERSAL::can()\fR) then the call will be skipped. If the method dies a |
| 343 | warning will be generated. |
| 344 | .IP "\(bu" 4 |
| 345 | $Data::Dumper::Toaster \fIor\fR $\fI\s-1OBJ\s0\fR\->Toaster(\fI[\s-1NEWVAL\s0]\fR) |
| 346 | .Sp |
| 347 | Can be set to a method name, or to an empty string to disable the feature. |
| 348 | Data::Dumper will emit a method call for any objects that are to be dumped |
| 349 | using the syntax \f(CW\*(C`bless(DATA, CLASS)\->METHOD()\*(C'\fR. Note that this means that |
| 350 | the method specified will have to perform any modifications required on the |
| 351 | object (like creating new state within it, and/or reblessing it in a |
| 352 | different package) and then return it. The client is responsible for making |
| 353 | sure the method can be called via the object, and that it returns a valid |
| 354 | object. Defaults to an empty string. |
| 355 | .IP "\(bu" 4 |
| 356 | $Data::Dumper::Deepcopy \fIor\fR $\fI\s-1OBJ\s0\fR\->Deepcopy(\fI[\s-1NEWVAL\s0]\fR) |
| 357 | .Sp |
| 358 | Can be set to a boolean value to enable deep copies of structures. |
| 359 | Cross-referencing will then only be done when absolutely essential |
| 360 | (i.e., to break reference cycles). Default is 0. |
| 361 | .IP "\(bu" 4 |
| 362 | $Data::Dumper::Quotekeys \fIor\fR $\fI\s-1OBJ\s0\fR\->Quotekeys(\fI[\s-1NEWVAL\s0]\fR) |
| 363 | .Sp |
| 364 | Can be set to a boolean value to control whether hash keys are quoted. |
| 365 | A false value will avoid quoting hash keys when it looks like a simple |
| 366 | string. Default is 1, which will always enclose hash keys in quotes. |
| 367 | .IP "\(bu" 4 |
| 368 | $Data::Dumper::Bless \fIor\fR $\fI\s-1OBJ\s0\fR\->Bless(\fI[\s-1NEWVAL\s0]\fR) |
| 369 | .Sp |
| 370 | Can be set to a string that specifies an alternative to the \f(CW\*(C`bless\*(C'\fR |
| 371 | builtin operator used to create objects. A function with the specified |
| 372 | name should exist, and should accept the same arguments as the builtin. |
| 373 | Default is \f(CW\*(C`bless\*(C'\fR. |
| 374 | .IP "\(bu" 4 |
| 375 | $Data::Dumper::Pair \fIor\fR $\fI\s-1OBJ\s0\fR\->Pair(\fI[\s-1NEWVAL\s0]\fR) |
| 376 | .Sp |
| 377 | Can be set to a string that specifies the separator between hash keys |
| 378 | and values. To dump nested hash, array and scalar values to JavaScript, |
| 379 | use: \f(CW\*(C`$Data::Dumper::Pair = ' : ';\*(C'\fR. Implementing \f(CW\*(C`bless\*(C'\fR in JavaScript |
| 380 | is left as an exercise for the reader. |
| 381 | A function with the specified name exists, and accepts the same arguments |
| 382 | as the builtin. |
| 383 | .Sp |
| 384 | Default is: \f(CW\*(C` => \*(C'\fR. |
| 385 | .IP "\(bu" 4 |
| 386 | $Data::Dumper::Maxdepth \fIor\fR $\fI\s-1OBJ\s0\fR\->Maxdepth(\fI[\s-1NEWVAL\s0]\fR) |
| 387 | .Sp |
| 388 | Can be set to a positive integer that specifies the depth beyond which |
| 389 | which we don't venture into a structure. Has no effect when |
| 390 | \&\f(CW\*(C`Data::Dumper::Purity\*(C'\fR is set. (Useful in debugger when we often don't |
| 391 | want to see more than enough). Default is 0, which means there is |
| 392 | no maximum depth. |
| 393 | .IP "\(bu" 4 |
| 394 | $Data::Dumper::Useperl \fIor\fR $\fI\s-1OBJ\s0\fR\->Useperl(\fI[\s-1NEWVAL\s0]\fR) |
| 395 | .Sp |
| 396 | Can be set to a boolean value which controls whether the pure Perl |
| 397 | implementation of \f(CW\*(C`Data::Dumper\*(C'\fR is used. The \f(CW\*(C`Data::Dumper\*(C'\fR module is |
| 398 | a dual implementation, with almost all functionality written in both |
| 399 | pure Perl and also in \s-1XS\s0 ('C'). Since the \s-1XS\s0 version is much faster, it |
| 400 | will always be used if possible. This option lets you override the |
| 401 | default behavior, usually for testing purposes only. Default is 0, which |
| 402 | means the \s-1XS\s0 implementation will be used if possible. |
| 403 | .IP "\(bu" 4 |
| 404 | $Data::Dumper::Sortkeys \fIor\fR $\fI\s-1OBJ\s0\fR\->Sortkeys(\fI[\s-1NEWVAL\s0]\fR) |
| 405 | .Sp |
| 406 | Can be set to a boolean value to control whether hash keys are dumped in |
| 407 | sorted order. A true value will cause the keys of all hashes to be |
| 408 | dumped in Perl's default sort order. Can also be set to a subroutine |
| 409 | reference which will be called for each hash that is dumped. In this |
| 410 | case \f(CW\*(C`Data::Dumper\*(C'\fR will call the subroutine once for each hash, |
| 411 | passing it the reference of the hash. The purpose of the subroutine is |
| 412 | to return a reference to an array of the keys that will be dumped, in |
| 413 | the order that they should be dumped. Using this feature, you can |
| 414 | control both the order of the keys, and which keys are actually used. In |
| 415 | other words, this subroutine acts as a filter by which you can exclude |
| 416 | certain keys from being dumped. Default is 0, which means that hash keys |
| 417 | are not sorted. |
| 418 | .IP "\(bu" 4 |
| 419 | $Data::Dumper::Deparse \fIor\fR $\fI\s-1OBJ\s0\fR\->Deparse(\fI[\s-1NEWVAL\s0]\fR) |
| 420 | .Sp |
| 421 | Can be set to a boolean value to control whether code references are |
| 422 | turned into perl source code. If set to a true value, \f(CW\*(C`B::Deparse\*(C'\fR |
| 423 | will be used to get the source of the code reference. Using this option |
| 424 | will force using the Perl implementation of the dumper, since the fast |
| 425 | \&\s-1XSUB\s0 implementation doesn't support it. |
| 426 | .Sp |
| 427 | Caution : use this option only if you know that your coderefs will be |
| 428 | properly reconstructed by \f(CW\*(C`B::Deparse\*(C'\fR. |
| 429 | .Sh "Exports" |
| 430 | .IX Subsection "Exports" |
| 431 | .IP "Dumper" 4 |
| 432 | .IX Item "Dumper" |
| 433 | .SH "EXAMPLES" |
| 434 | .IX Header "EXAMPLES" |
| 435 | Run these code snippets to get a quick feel for the behavior of this |
| 436 | module. When you are through with these examples, you may want to |
| 437 | add or change the various configuration variables described above, |
| 438 | to see their behavior. (See the testsuite in the Data::Dumper |
| 439 | distribution for more examples.) |
| 440 | .PP |
| 441 | .Vb 1 |
| 442 | \& use Data::Dumper; |
| 443 | .Ve |
| 444 | .PP |
| 445 | .Vb 2 |
| 446 | \& package Foo; |
| 447 | \& sub new {bless {'a' => 1, 'b' => sub { return "foo" }}, $_[0]}; |
| 448 | .Ve |
| 449 | .PP |
| 450 | .Vb 2 |
| 451 | \& package Fuz; # a weird REF-REF-SCALAR object |
| 452 | \& sub new {bless \e($_ = \e 'fu\e'z'), $_[0]}; |
| 453 | .Ve |
| 454 | .PP |
| 455 | .Vb 6 |
| 456 | \& package main; |
| 457 | \& $foo = Foo->new; |
| 458 | \& $fuz = Fuz->new; |
| 459 | \& $boo = [ 1, [], "abcd", \e*foo, |
| 460 | \& {1 => 'a', 023 => 'b', 0x45 => 'c'}, |
| 461 | \& \e\e"p\eq\e'r", $foo, $fuz]; |
| 462 | .Ve |
| 463 | .PP |
| 464 | .Vb 3 |
| 465 | \& ######## |
| 466 | \& # simple usage |
| 467 | \& ######## |
| 468 | .Ve |
| 469 | .PP |
| 470 | .Vb 3 |
| 471 | \& $bar = eval(Dumper($boo)); |
| 472 | \& print($@) if $@; |
| 473 | \& print Dumper($boo), Dumper($bar); # pretty print (no array indices) |
| 474 | .Ve |
| 475 | .PP |
| 476 | .Vb 3 |
| 477 | \& $Data::Dumper::Terse = 1; # don't output names where feasible |
| 478 | \& $Data::Dumper::Indent = 0; # turn off all pretty print |
| 479 | \& print Dumper($boo), "\en"; |
| 480 | .Ve |
| 481 | .PP |
| 482 | .Vb 2 |
| 483 | \& $Data::Dumper::Indent = 1; # mild pretty print |
| 484 | \& print Dumper($boo); |
| 485 | .Ve |
| 486 | .PP |
| 487 | .Vb 2 |
| 488 | \& $Data::Dumper::Indent = 3; # pretty print with array indices |
| 489 | \& print Dumper($boo); |
| 490 | .Ve |
| 491 | .PP |
| 492 | .Vb 2 |
| 493 | \& $Data::Dumper::Useqq = 1; # print strings in double quotes |
| 494 | \& print Dumper($boo); |
| 495 | .Ve |
| 496 | .PP |
| 497 | .Vb 2 |
| 498 | \& $Data::Dumper::Pair = " : "; # specify hash key/value separator |
| 499 | \& print Dumper($boo); |
| 500 | .Ve |
| 501 | .PP |
| 502 | .Vb 3 |
| 503 | \& ######## |
| 504 | \& # recursive structures |
| 505 | \& ######## |
| 506 | .Ve |
| 507 | .PP |
| 508 | .Vb 8 |
| 509 | \& @c = ('c'); |
| 510 | \& $c = \e@c; |
| 511 | \& $b = {}; |
| 512 | \& $a = [1, $b, $c]; |
| 513 | \& $b->{a} = $a; |
| 514 | \& $b->{b} = $a->[1]; |
| 515 | \& $b->{c} = $a->[2]; |
| 516 | \& print Data::Dumper->Dump([$a,$b,$c], [qw(a b c)]); |
| 517 | .Ve |
| 518 | .PP |
| 519 | .Vb 3 |
| 520 | \& $Data::Dumper::Purity = 1; # fill in the holes for eval |
| 521 | \& print Data::Dumper->Dump([$a, $b], [qw(*a b)]); # print as @a |
| 522 | \& print Data::Dumper->Dump([$b, $a], [qw(*b a)]); # print as %b |
| 523 | .Ve |
| 524 | .PP |
| 525 | .Vb 2 |
| 526 | \& $Data::Dumper::Deepcopy = 1; # avoid cross-refs |
| 527 | \& print Data::Dumper->Dump([$b, $a], [qw(*b a)]); |
| 528 | .Ve |
| 529 | .PP |
| 530 | .Vb 2 |
| 531 | \& $Data::Dumper::Purity = 0; # avoid cross-refs |
| 532 | \& print Data::Dumper->Dump([$b, $a], [qw(*b a)]); |
| 533 | .Ve |
| 534 | .PP |
| 535 | .Vb 3 |
| 536 | \& ######## |
| 537 | \& # deep structures |
| 538 | \& ######## |
| 539 | .Ve |
| 540 | .PP |
| 541 | .Vb 7 |
| 542 | \& $a = "pearl"; |
| 543 | \& $b = [ $a ]; |
| 544 | \& $c = { 'b' => $b }; |
| 545 | \& $d = [ $c ]; |
| 546 | \& $e = { 'd' => $d }; |
| 547 | \& $f = { 'e' => $e }; |
| 548 | \& print Data::Dumper->Dump([$f], [qw(f)]); |
| 549 | .Ve |
| 550 | .PP |
| 551 | .Vb 2 |
| 552 | \& $Data::Dumper::Maxdepth = 3; # no deeper than 3 refs down |
| 553 | \& print Data::Dumper->Dump([$f], [qw(f)]); |
| 554 | .Ve |
| 555 | .PP |
| 556 | .Vb 3 |
| 557 | \& ######## |
| 558 | \& # object-oriented usage |
| 559 | \& ######## |
| 560 | .Ve |
| 561 | .PP |
| 562 | .Vb 6 |
| 563 | \& $d = Data::Dumper->new([$a,$b], [qw(a b)]); |
| 564 | \& $d->Seen({'*c' => $c}); # stash a ref without printing it |
| 565 | \& $d->Indent(3); |
| 566 | \& print $d->Dump; |
| 567 | \& $d->Reset->Purity(0); # empty the seen cache |
| 568 | \& print join "----\en", $d->Dump; |
| 569 | .Ve |
| 570 | .PP |
| 571 | .Vb 3 |
| 572 | \& ######## |
| 573 | \& # persistence |
| 574 | \& ######## |
| 575 | .Ve |
| 576 | .PP |
| 577 | .Vb 8 |
| 578 | \& package Foo; |
| 579 | \& sub new { bless { state => 'awake' }, shift } |
| 580 | \& sub Freeze { |
| 581 | \& my $s = shift; |
| 582 | \& print STDERR "preparing to sleep\en"; |
| 583 | \& $s->{state} = 'asleep'; |
| 584 | \& return bless $s, 'Foo::ZZZ'; |
| 585 | \& } |
| 586 | .Ve |
| 587 | .PP |
| 588 | .Vb 7 |
| 589 | \& package Foo::ZZZ; |
| 590 | \& sub Thaw { |
| 591 | \& my $s = shift; |
| 592 | \& print STDERR "waking up\en"; |
| 593 | \& $s->{state} = 'awake'; |
| 594 | \& return bless $s, 'Foo'; |
| 595 | \& } |
| 596 | .Ve |
| 597 | .PP |
| 598 | .Vb 10 |
| 599 | \& package Foo; |
| 600 | \& use Data::Dumper; |
| 601 | \& $a = Foo->new; |
| 602 | \& $b = Data::Dumper->new([$a], ['c']); |
| 603 | \& $b->Freezer('Freeze'); |
| 604 | \& $b->Toaster('Thaw'); |
| 605 | \& $c = $b->Dump; |
| 606 | \& print $c; |
| 607 | \& $d = eval $c; |
| 608 | \& print Data::Dumper->Dump([$d], ['d']); |
| 609 | .Ve |
| 610 | .PP |
| 611 | .Vb 3 |
| 612 | \& ######## |
| 613 | \& # symbol substitution (useful for recreating CODE refs) |
| 614 | \& ######## |
| 615 | .Ve |
| 616 | .PP |
| 617 | .Vb 6 |
| 618 | \& sub foo { print "foo speaking\en" } |
| 619 | \& *other = \e&foo; |
| 620 | \& $bar = [ \e&other ]; |
| 621 | \& $d = Data::Dumper->new([\e&other,$bar],['*other','bar']); |
| 622 | \& $d->Seen({ '*foo' => \e&foo }); |
| 623 | \& print $d->Dump; |
| 624 | .Ve |
| 625 | .PP |
| 626 | .Vb 3 |
| 627 | \& ######## |
| 628 | \& # sorting and filtering hash keys |
| 629 | \& ######## |
| 630 | .Ve |
| 631 | .PP |
| 632 | .Vb 5 |
| 633 | \& $Data::Dumper::Sortkeys = \e&my_filter; |
| 634 | \& my $foo = { map { (ord, "$_$_$_") } 'I'..'Q' }; |
| 635 | \& my $bar = { %$foo }; |
| 636 | \& my $baz = { reverse %$foo }; |
| 637 | \& print Dumper [ $foo, $bar, $baz ]; |
| 638 | .Ve |
| 639 | .PP |
| 640 | .Vb 13 |
| 641 | \& sub my_filter { |
| 642 | \& my ($hash) = @_; |
| 643 | \& # return an array ref containing the hash keys to dump |
| 644 | \& # in the order that you want them to be dumped |
| 645 | \& return [ |
| 646 | \& # Sort the keys of %$foo in reverse numeric order |
| 647 | \& $hash eq $foo ? (sort {$b <=> $a} keys %$hash) : |
| 648 | \& # Only dump the odd number keys of %$bar |
| 649 | \& $hash eq $bar ? (grep {$_ % 2} keys %$hash) : |
| 650 | \& # Sort keys in default order for all other hashes |
| 651 | \& (sort keys %$hash) |
| 652 | \& ]; |
| 653 | \& } |
| 654 | .Ve |
| 655 | .SH "BUGS" |
| 656 | .IX Header "BUGS" |
| 657 | Due to limitations of Perl subroutine call semantics, you cannot pass an |
| 658 | array or hash. Prepend it with a \f(CW\*(C`\e\*(C'\fR to pass its reference instead. This |
| 659 | will be remedied in time, now that Perl has subroutine prototypes. |
| 660 | For now, you need to use the extended usage form, and prepend the |
| 661 | name with a \f(CW\*(C`*\*(C'\fR to output it as a hash or array. |
| 662 | .PP |
| 663 | \&\f(CW\*(C`Data::Dumper\*(C'\fR cheats with \s-1CODE\s0 references. If a code reference is |
| 664 | encountered in the structure being processed (and if you haven't set |
| 665 | the \f(CW\*(C`Deparse\*(C'\fR flag), an anonymous subroutine that |
| 666 | contains the string '\*(L"\s-1DUMMY\s0\*(R"' will be inserted in its place, and a warning |
| 667 | will be printed if \f(CW\*(C`Purity\*(C'\fR is set. You can \f(CW\*(C`eval\*(C'\fR the result, but bear |
| 668 | in mind that the anonymous sub that gets created is just a placeholder. |
| 669 | Someday, perl will have a switch to cache-on-demand the string |
| 670 | representation of a compiled piece of code, I hope. If you have prior |
| 671 | knowledge of all the code refs that your data structures are likely |
| 672 | to have, you can use the \f(CW\*(C`Seen\*(C'\fR method to pre-seed the internal reference |
| 673 | table and make the dumped output point to them, instead. See \*(L"\s-1EXAMPLES\s0\*(R" |
| 674 | above. |
| 675 | .PP |
| 676 | The \f(CW\*(C`Useqq\*(C'\fR and \f(CW\*(C`Deparse\*(C'\fR flags makes \fIDump()\fR run slower, since the |
| 677 | \&\s-1XSUB\s0 implementation does not support them. |
| 678 | .PP |
| 679 | \&\s-1SCALAR\s0 objects have the weirdest looking \f(CW\*(C`bless\*(C'\fR workaround. |
| 680 | .PP |
| 681 | Pure Perl version of \f(CW\*(C`Data::Dumper\*(C'\fR escapes \s-1UTF\-8\s0 strings correctly |
| 682 | only in Perl 5.8.0 and later. |
| 683 | .Sh "\s-1NOTE\s0" |
| 684 | .IX Subsection "NOTE" |
| 685 | Starting from Perl 5.8.1 different runs of Perl will have different |
| 686 | ordering of hash keys. The change was done for greater security, |
| 687 | see \*(L"Algorithmic Complexity Attacks\*(R" in perlsec. This means that |
| 688 | different runs of Perl will have different Data::Dumper outputs if |
| 689 | the data contains hashes. If you need to have identical Data::Dumper |
| 690 | outputs from different runs of Perl, use the environment variable |
| 691 | \&\s-1PERL_HASH_SEED\s0, see \*(L"\s-1PERL_HASH_SEED\s0\*(R" in perlrun. Using this restores |
| 692 | the old (platform\-specific) ordering: an even prettier solution might |
| 693 | be to use the \f(CW\*(C`Sortkeys\*(C'\fR filter of Data::Dumper. |
| 694 | .SH "AUTHOR" |
| 695 | .IX Header "AUTHOR" |
| 696 | Gurusamy Sarathy gsar@activestate.com |
| 697 | .PP |
| 698 | Copyright (c) 1996\-98 Gurusamy Sarathy. All rights reserved. |
| 699 | This program is free software; you can redistribute it and/or |
| 700 | modify it under the same terms as Perl itself. |
| 701 | .SH "VERSION" |
| 702 | .IX Header "VERSION" |
| 703 | Version 2.121 (Aug 24 2003) |
| 704 | .SH "SEE ALSO" |
| 705 | .IX Header "SEE ALSO" |
| 706 | \&\fIperl\fR\|(1) |