Support nullable types

[weierophinney]

As per PHP 7.1, it is possible to define nullability of a type by adding a ? in front of it ( https://wiki.php.net/rfc/nullable_types ).

A few heads-up:

• careful about ?Foo $bar = null vs ?Foo $bar vs Foo $bar = null
• need to eventually patch the TypeGenerator to include the ? in it (not sure yet)

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Originally posted by @Ocramius at zendframework/zend-code#85

[weierophinney]

Surely resolving the fact that Zend\Code\Scanner\MethodScanner doesn't properly handle scalar type declarations should come before supporting nullable types? #56 still hasn't received any acknowledgement.

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Originally posted by @djmattyg007 at zendframework/zend-code#85 (comment)

[weierophinney]

@djmattyg007 I reported the issue completely independently from other issues.

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Originally posted by @Ocramius at zendframework/zend-code#85 (comment)

[weierophinney]

My point was that PHP 7.0 compatibility should be targeted before PHP 7.1 compatibility.

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Originally posted by @djmattyg007 at zendframework/zend-code#85 (comment)

[weierophinney]

Ah yes, that is because the codegen part of this component is already 7.0 compatible. I hardly ever use the scanner, as it is not AST-based (which makes it very unstable)

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Originally posted by @Ocramius at zendframework/zend-code#85 (comment)

[weierophinney]

If no one is maintaining the scanning code, shouldn't it be removed?

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Originally posted by @djmattyg007 at zendframework/zend-code#85 (comment)

[Ocramius]

No longer needed as per #58