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	diff --git a/src/docs/contributor/php_coding_standards.diviner b/src/docs/contributor/php_coding_standards.diviner
	--- a/src/docs/contributor/php_coding_standards.diviner
	+++ b/src/docs/contributor/php_coding_standards.diviner
	@@ -176,3 +176,7 @@
	return $this->favoriteFood;
	}
	}
	+
	+# Extra Readings
	+
	+* @{article:PHP Pitfalls}
	diff --git a/src/docs/flavor/php_pitfalls.diviner b/src/docs/flavor/php_pitfalls.diviner
	--- a/src/docs/flavor/php_pitfalls.diviner
	+++ b/src/docs/flavor/php_pitfalls.diviner
	@@ -49,18 +49,7 @@
	false // boolean
	array() // empty array

	-Disregarding some bizarre edge cases, all other values are truthy. Note that
	-because "0" is falsey, this sort of thing (intended to prevent users from making
	-empty comments) is wrong in PHP:
	-
	- COUNTEREXAMPLE
	- if ($comment_text) {
	- make_comment($comment_text);
	- }
	-
	-This is wrong because it prevents users from making the comment "0". //THIS
	-COMMENT IS TOTALLY AWESOME AND I MAKE IT ALL THE TIME SO YOU HAD BETTER NOT
	-BREAK IT!!!// A better test is probably `strlen()`.
	+Disregarding some bizarre edge cases, all other values are truthy.

	In addition to truth tests with `if`, PHP has two special truthiness operators
	which look like functions but aren't: `empty()` and `isset()`. These operators
	@@ -92,16 +81,16 @@
	`empty()` evaluates truthiness exactly opposite of `if()`. `isset()` returns
	`true` for everything except `null`. This is the truth table:

	-\| Value \| `if()` \| `empty()` \| `isset()` \|
	-\|-------\|--------\|-----------\|-----------\|
	-\| `null` \| `false` \| `true` \| `false` \|
	-\| `0` \| `false` \| `true` \| `true` \|
	-\| `0.0` \| `false` \| `true` \| `true` \|
	-\| `"0"` \| `false` \| `true` \| `true` \|
	-\| `""` \| `false` \| `true` \| `true` \|
	-\| `false` \| `false` \| `true` \| `true` \|
	-\| `array()` \| `false` \| `true` \| `true` \|
	-\| Everything else \| `true` \| `false` \| `true` \|
	+\| Value \| `if()` \| `empty()` \| `isset()` \|
	+\|---------------\|--------\|-----------\|-----------\|
	+\| `null` \| `false`\| `true` \| `false` \|
	+\| `0` \| `false`\| `true` \| `true` \|
	+\| `0.0` \| `false`\| `true` \| `true` \|
	+\| `"0"` \| `false`\| `true` \| `true` \|
	+\| `""` \| `false`\| `true` \| `true` \|
	+\|`false` \| `false`\| `true` \| `true` \|
	+\|`array()` \| `false`\| `true` \| `true` \|
	+\|Everything else\| `true` \| `false` \| `true` \|

	The value of these operators is that they accept undeclared variables and do
	not issue a warning. Specifically, if you try to do this you get a warning:
	@@ -138,6 +127,63 @@
	are testing something that may not be declared. Use `empty()` if you want to
	type `if (!$value)` but you are testing something that may not be declared.

	+= Check for non-empty strings =
	+
	+As already mentioned, note that you cannot just use an `if` or `empty()` to
	+check for a non-empty string, mostly because "0" is falsey, so you cannot rely
	+on this sort of thing to prevent users from making empty comments:
	+
	+ COUNTEREXAMPLE
	+ if ($comment_text) {
	+ make_comment($comment_text);
	+ }
	+
	+This is wrong because it prevents users from making the comment "0".
	+
	+//THE COMMENT "0" IS TOTALLY AWESOME AND I MAKE IT ALL THE TIME SO YOU HAD
	+BETTER NOT BREAK IT!!!//
	+
	+Another way //was// also `strlen()`:
	+
	+ COUNTEREXAMPLE
	+ if (strlen($comment_text)) {
	+ make_comment($comment_text);
	+ }
	+
	+But `strlen()` wastes too many CPU cycles to just check of a non-empty
	+string, and, `strlen()` also comes with these funny things:
	+
	+\| Check \| Return \|
	+\|-----------------\|--------\|
	+\| `strlen(false)` \| `0` \|
	+\| `strlen(true)` \| `1` \|
	+\| `strlen(null)` \| deprecation exception since PHP 8.1 \|
	+
	+As solution, you can start using `is_string()` that requires a
	+variable of type string (and it also excludes null).
	+
	+In short, this is a good way to check for non-empty strings:
	+
	+```lang=php
	+ if (is_string($value) && $value !== '') {
	+ // do something
	+ }
	+```
	+
	+If you like that method, this is a shortcut provided by Arcanist:
	+
	+```lang=php
	+ if (phutil_nonempty_string($value)) {
	+ // do something
	+ }
	+```
	+
	+But note, if you use `phutil_nonempty_string()`, this function is designed
	+to throw an exception if it receives `true`, `false`, an array, an object
	+or anything alien. This is an extra security measure to detect funny things
	+coming from input sources. Do your evaluations but probably this is what
	+you want.
	+
	= usort(), uksort(), and uasort() are Slow =

	This family of functions is often extremely slow for large datasets. You should

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