merged branch rybakit/constant (PR #966)

This PR was merged into the master branch.

Commits
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a1b7ec5 Tweak twig_constant()

Discussion
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Tweak twig_constant()

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by Tobion at 2013-01-16T10:52:56Z

Why is it better? The old version returns earlier.

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by rybakit at 2013-01-16T11:25:39Z

It's better for several reasons, imho:
1. Negation has gone, which is better for perception
2. Single function exit point
3. The same functionality in less code

And what do you mean by "The old version returns earlier"?

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by Tobion at 2013-01-16T13:33:22Z

It means the old version uses a variable less and we prefer early return statements when possible.

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by rybakit at 2013-01-16T14:24:26Z

@Tobion, but how could it be "earlier"? In both cases the ```return``` statement goes exactly after the condition check:

1)
```php
if (!$object) {                   // 1. check condition
    return constant($constant);   // 2. return result
}
```
2)
```php
if ($object) {                    // 1. check condition
    // ...
}

return constant($constant);       // 2. return result
```
Do you want to say that case 1) is faster?