PHP equivalent for Python's repr() [duplicate] - php

Question

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PHP Array to String equivalent
(1 answer)
Closed 10 years ago.
I'm creating a simple array wrapper class and want it's __toString() method to be formatted like a Python list, eg: ["foo", "bar", 6, 21.00002351]. Converting each element to a string is not enough, since string-objects are actually enquoted in the list-representation.
Is there a repr() equivalent in PHP, and if not, what would a PHP implementation look like?

Answer 1

Python's repr() returns an output where
eval(repr(object)) == object
Called by the repr() built-in function and by string conversions (reverse quotes) to compute the “official” string representation of an object. If at all possible, this should look like a valid Python expression that could be used to recreate an object with the same value (given an appropriate environment).
So the closest thing in PHP would be
var_export — Outputs or returns a parsable string representation of a variable
The keyword here is parseable. While functions print_r and var_dump will give a certain representation of the data passed to them, they are not easily parseable, nor do they look like PHP expression, which could be eval'd.
Example:
var_export(['foo', 'bar', 1,2,3]);
will give
array (
0 => 'foo',
1 => 'bar',
2 => 1,
3 => 2,
4 => 3,
)
and that is perfectly valid PHP code:
$data = ['foo', 'bar', 1, 2, 3];
$repr = var_export($data, true);
// have to use it with return though to eval it back into a var
$evald = eval("return $repr;");
var_dump($evald == $data); // true
Another option would be to use serialize to get a canonical and parseable representation of a data type, e.g.
$data = ['foo', 'bar', 1, 2, 3];
$repr = serialize($data);
// -> a:5:{i:0;s:3:"foo";i:1;s:3:"bar";i:2;i:1;i:3;i:2;i:4;i:3;}
var_dump( unserialize($repr) == $data ); // true
Unlike var_export, the resulting representation is not a PHP expression, but a compacted string indicating the type and it's properties/values (a serialization).
But you are likely just looking for json_encode as pointed out elsewhere.
Making this a Community Wiki because I've already answered this in the given dupe.

Answer 2

I don't know Python but PHP arrays can contain any data type and nesting levels. I don't know how that translates into your format.
There're many functions to print an array:
print_r()
var_dump()
var_export()
... but your format reminds me of JSON so you can simply do this:
<?php
$foo = array (
'foo',
'bar',
6,
21.00002351,
);
echo json_encode($foo); // ["foo","bar",6,21.00002351]
Of course, it's by no means automatic, i.e., this won't trigger any toString() method at all:
echo $foo; // "Array" + PHP Notice: Array to string conversion