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Add docs for null coalescing

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Simon Wisselink
2023-05-01 23:57:53 +02:00
parent e99d2fae39
commit f7868b4ff1
1 changed files with 15 additions and 1 deletions
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docs/designers/language-basic-syntax/language-syntax-operators.md
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@@ -29,7 +29,7 @@ Various basic operators can be applied directly to variable values.
## Ternary ## Ternary
You can use the `?:` (or ternary) operator to test one expression and present the value You can use the `?:` (or ternary) operator to test one expression and present the value
of the second or third expression, based on the result of te test. of the second or third expression, based on the result of the test.
In other words: In other words:
```smarty ```smarty
@@ -47,4 +47,18 @@ return 'hello':
```smarty ```smarty
{$myVar="hello"} {$myVar="hello"}
{$myVar ?: "empty"} {$myVar ?: "empty"}
```
## Testing for null
If "something that evaluates to false" is to broad a test for you, you can use the `??` (or null coalescing) operator
to trigger only if the tested value is undefined or set to null.
```smarty
{$myVar ?? "empty"}
```
will result in 'empty' if `$myVar` is not set or set to null.
If `$myVar` is set to something that evaluates to anything else, the value of `$myVar` is returned. So, the following will
return an empty string (''):
```smarty
{$myVar=""}
{$myVar ?: "this is not shown"}
``` ```