New in Symfony 3.2: Better readability for YAML numeric literals

Contributed by
Baptiste Clavié
in #18486.

Long numeric literals, being integer, float or hexadecimal, are known for their poor readability in code and configuration files:

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parameters:
    credit_card_number: 1234567890123456
    long_number: 10000000000
    pi: 3.141592653589793
    hex_words: 0xCAFEF00D

In Symfony 3.2, YAML files added support for including underscores in numeric literals to improve their readability:

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parameters:
    credit_card_number: 1234_5678_9012_3456
    long_number: 10_000_000_000
    pi: 3.14159_26535_89793
    hex_words: 0x_CAFE_F00D

During the parsing of the YAML contents, all the _ characters are removed from the numeric literal contents, so there is not a limit in the number of underscores you can include or the way you group contents.

This feature is defined in the YAML specification and it's widely supported in other programming languages (Java, Ruby, Rust, Swift, etc.).

Deprecating comma separators in floats

Contributed by
Christian Flothmann
in #18785.

The new underscore separator made us think about the need of the comma to separate the float number contents. Ultimately we decided to deprecate it, so starting from Symfony 3.2, the use of the comma to separate contents is deprecated:

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parameters:
    # deprecated since Symfony 3.2
    foo: 1,230.15

    # equivalent without the comma separator
    foo: 1230.15

    # equivalent with the underscore separator
    foo: 1_230.15