在PHP代码中使用下划线[重复]

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• Double Underscore in PHP? 5 answers

Firstly, to be clear, I'm not talking about the use of underscores as for visual separation of words in function names, etc., for example from the code below, woocommerce_wp_text_input.

In following a particular PHP WordPress WooCommerce related tutorial, I noticed the coder was randomly inserting underscores and multiple consecutive underscores, for example: _text_field and __( 'Enter the custom value here.', 'woocommerce' ). This is either a convention that is used in demonstration code snippets or it has some PHP meaning.

    // Text Field
woocommerce_wp_text_input( 
    array( 
        'id'          => '_text_field[' . $variation->ID . ']', 
        'label'       => __( 'My Text Field', 'woocommerce' ), 
        'placeholder' => 'http://',
        'desc_tip'    => 'true',
        'description' => __( 'Enter the custom value here.', 'woocommerce' ),
        'value'       => get_post_meta( $variation->ID, '_text_field', true )
    )
);

Is there a convention regarding the use of an arbitrary number of underscores in coding demonstrations? At first I suspected he was using underscores to highlight that certain values were specific to his case, but I really don't know.

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Answer 1

There isn't any convention.

_() (one underscore) is an alias of the PHP function gettext(). It is used for localization.

__() (two underscores) is a function defined by Wordpress, also for localization. You can think at it as a more flexible version of _() but it is available only in WP projects.