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Depict

A fast, recursion-safe, and succinct replacement for var_dump/var_export/print_r.

Installation

• Available as Composer package eloquent/depict.

Usage

use Eloquent\Depict\InlineExporter;

$exporter = InlineExporter::create();
echo $exporter->export(['a', 'b', 'c', 1, 2, 3]); // outputs '#0["a", "b", "c", 1, 2, 3]'

What is Depict?

Depict is a var_dump()/var_export()/print_r() replacement that focuses on performance, succinctness, and recursion safety. In contrast to many of the available libraries providing similar functionality, Depict is designed specifically for command line output (not HTML).

Depict is based on the exporter used by Phony, and is essentially the same code, with the Phony-specific parts removed.

Exporters

Depict currently implements only one exporter, the InlineExporter. More exporters may be implemented in future. Exporters implement a very simple Exporter interface.

InlineExporter

This exporter is designed for single-line output of values. To create an inline exporter, use InlineExporter::create():

$exporter = InlineExporter::create();

InlineExporter::create() can also accept an options array to customize its output:

$exporter = InlineExporter::create(['depth' => 1]);

Available options for InlineExporter::create():

Option	Description	Default
depth	An integer that determines the depth to which Depict will export before truncating output. Negative values are treated as infinite depth.	-1
breadth	An integer that determines the number of sub-values that Depict will export before truncating output. Negative values are treated as infinite breadth.	-1
useShortNames	When true, Depict will omit namespace information from exported symbol names.	true
useShortPaths	When true, Depict will export only the basename of closure paths.	false

The export format

Depict generates a concise, unambiguous, human-readable representation of any PHP value, including recursive objects and arrays:

Input value	Exporter output
null	'null'
true	'true'
false	'false'
111	'111'
1.11	'1.110000e+0'
'1.11'	'"1.11"'
"a\nb"	'"a\nb"'
STDIN	'resource#1'
[1, 2]	'#0[1, 2]'
['a' => 1, 'b' => 2]	'#0["a": 1, "b": 2]
(object) ['a' => 1, 'b' => 2]	'#0{a: 1, b: 2}'
new ClassA()	'ClassA#0{}'

Export identifiers and references

Exported arrays, and objects include a numeric identifier that can be used to identify repeated occurrences of the same value. This is represented as a number sign (#) followed by the identifier:

$value = (object) array();
// $value is exported as '#0{}'

When a value appears multiple times, its internal structure will only be described the first time. Subsequent appearances will be indicated by a reference to the value's identifier. This is represented as an ampersand (&) followed by the identifier:

$inner = [1, 2];
$value = [&$inner, &$inner];
// $value is exported as '#0[#1[1, 2], &1[]]'

$inner = (object) ['a' => 1];
$value = (object) ['b' => $inner, 'c' => $inner];
// $value is exported as '#0{b: #1{a: 1}, c: &1{}}'

Export reference types

Array references appear followed by brackets (e.g. &0[]), and object references appear followed by braces (e.g. &0{}):

$array = [];
$object = (object) [];

$value = [&$array, &$array];
// $value is exported as '#0[#1[], &1[]]'

$value = [$object, $object];
// $value is exported as '#0[#0{}, &0{}]'

This is necessary in order to disambiguate references, because arrays and other types can sometimes have the same identifier:

$value = [
    (object) [],
    [
        (object) [],
    ],
];
// $value is exported as '#0[#0{}, #1[#1{}]]'

Export reference exclusions

As well as excluding the content, object references exclude the class name, for brevity:

$inner = new ClassA();
$inner->c = "d";
$value = (object) ['a' => $inner, 'b' => $inner];
// $value is exported as '#0{a: ClassA#1{c: "d"}, b: &1{}}'

Export identifier persistence

Identifiers for objects are persistent across invocations of an exporter, and share a single sequence of numbers:

$a = (object) [];
$b = (object) [];

$value = [$a, $b, $a];
// $value is exported as '#0[#0{}, #1{}, &0{}]'

$value = [$b, $a, $b];
// $value is exported as '#0[#1{}, #0{}, &1{}]'

But due to PHP's limitations, array identifiers are only persistent within a single exporter invocation:

$a = [];
$b = [];

$valueA = [&$a, &$b, &$a];
$valueB = [&$b, &$a, &$b];
// both $valueA and $valueB are exported as '#0[#1[], #2[], &1[]]'

Exporting recursive values

If a recursive value is exported, the points of recursion are exported as [references], in the same way that multiple instances of the same value are handled:

$value = [];
$value[] = &$value;
// $value is exported as '#0[&0[]]'

$value = (object) [];
$value->a = $value;
// $value is exported as '#0{a: &0{}}'

Exporter special cases

For certain types of values, exporters will exhibit special behavior, in order to improve the usefulness of its output, or to improve performance in common use cases.

Exporting closures

When a closure is exported, the file path and start line number are included in the output:

$closure = function () {}; // file path is /path/to/example.php, line number is 123
// $closure is exported as 'Closure#0{}[/path/to/example.php:123]'

Note that the class name will always be exported as Closure, even for runtimes such as HHVM that use different class names for closures.

Exporting exceptions

When an exception is exported, some internal PHP details are stripped from the output, including file path, line number, and stack trace:

$exception = new Exception('a', 1, new Exception());
// $exception is exported as 'Exception#0{message: "a", code: 1, previous: Exception#1{}}'

Additionally, when the message is '', the code is 0, and/or the previous exception is null, these values are excluded for brevity:

$exception = new RuntimeException();
// $exception is exported as 'RuntimeException#0{}'

Export depth and breadth

For complicated nested structures, exporting the entire structure is not always desirable. Depict can set limits on how much depth and breadth of the supplied value it will export.

When a value is beyond the export depth, and has sub-values, its contents will be replaced with a special notation that simply indicates how many sub-values exist within that value:

$value = [[], ['a', 'b', 'c']];
// with a depth of 1, $value is exported as '#0[#1[], #2[~3]]'

$value = [(object) [], (object) ['a', 'b', 'c']];
// with a depth of 1, $value is exported as '#0[#0{}, #1{~3}]'

When the breadth limit of a value has been reached, a similar notation is used to indicate how many sub-values remain unexported:

$value = ['a', 'b', 'c', 'd', 'e'];
// with a breadth of 2, $value is exported as '#0["a", "b", ~3]'