Python数组切片 - 如何实现二维数组切片？(Python array slicing — How can 2D array slicing be implemented?)

 这可能不是最酷的方式，但我认为它很漂亮。 
 
 Laravel有一个名为Form::macro的功能，可以让你制作可重用的代码片段。 你可以定义一个宏的所有类型的地方，但我只是在我的routes.php文件中打了我的这个真正的快速。 
 
Form::macro('errorMsg', function($field, $errors){
    if($errors->has($field)){
        $msg = $errors->first($field);
        return "<span class=\"error\">$msg</span>";
    }
    return '';
});
 
 然后在窗体中使用，将错误消息传递给宏： 
 
{{ Form::label('first_name', 'First Name:') }}
{{ Form::text('first_name') }}
{{ Form::errorMsg('first_name', $errors) }}
{{-- where $errors is your Illuminate\Support\MessageBag object --}}
 
 为了获得更多的技术，你可以在Form::macro使用Form::objects ，如下所示： 
 
Form::macro('textError', function($field, $label, $errors){
    $label_html = Form::label($field, $label);
    $text_html = Form::text($field);
    $msg_html = '';

    if($errors->has($field)){
            $msg_html.= '<span class="error">';
            $msg_html.= $errors->first($field);
            $msg_html.= '</span>';
    }

    return $label_html.$text_html.$msg_html;
});
 
 然后你在每个输入1行： 
 
{{ Form::textError('first_name', 'First Name:', $errors) }}
 
 您需要为密码，textarea等创建其他宏（这就是为什么我只使用第一个示例;每个输入只有几行代码，并提供所有输入类型。） 
 
 如果你想对错误进行输入，例如。 一个红色的边框，你可能会想要第二个例子，然后将它包裹在你的div.form-group或whatevers中。 无论如何，选择wazoo。 
 
 更新：在宏中获取错误的一种更简单的方式是通过Session::get('errors');来访问它们Session::get('errors'); 像这样： 
 
Form::macro('errorMsg', function($field){//yay! we don't have to pass $errors anymore
    $errors = Session::get('errors');

    if($errors && $errors->has($field)){//make sure $errors is not null
        $msg = $errors->first($field);
        return "<span class=\"error\">$msg</span>";
    }
    return '';
});

This may not be the coolest way to do this but I think it's pretty slick.
 
Laravel has a feature called Form::macro that allows you to sort of make reusable code snippets. You can define a macro all kinds of places but I just slapped mine in my routes.php file to get this going real quick.
 
Form::macro('errorMsg', function($field, $errors){
    if($errors->has($field)){
        $msg = $errors->first($field);
        return "<span class=\"error\">$msg</span>";
    }
    return '';
});
 
Then to use in a form, pass the macro your error messages:
 
{{ Form::label('first_name', 'First Name:') }}
{{ Form::text('first_name') }}
{{ Form::errorMsg('first_name', $errors) }}
{{-- where $errors is your Illuminate\Support\MessageBag object --}}
 
To get even more tech, you can use Form::objects in a Form::macro like so:
 
Form::macro('textError', function($field, $label, $errors){
    $label_html = Form::label($field, $label);
    $text_html = Form::text($field);
    $msg_html = '';

    if($errors->has($field)){
            $msg_html.= '<span class="error">';
            $msg_html.= $errors->first($field);
            $msg_html.= '</span>';
    }

    return $label_html.$text_html.$msg_html;
});
 
Then you're at 1 line per input:
 
{{ Form::textError('first_name', 'First Name:', $errors) }}
 
You'd need to make other macros for password, textarea, etc. (which is why I just use the first example; it's only a couple more lines of code per input and serves all input types.)
 
If you wanted to style your input on error, eg. a red border, you'd probably want the second example then wrap it in your div.form-group or whatevers. Anyway, options out the wazoo.
 
UPDATE: An even slicker way to get errors in macros is to access them via Session::get('errors'); like so:
 
Form::macro('errorMsg', function($field){//yay! we don't have to pass $errors anymore
    $errors = Session::get('errors');

    if($errors && $errors->has($field)){//make sure $errors is not null
        $msg = $errors->first($field);
        return "<span class=\"error\">$msg</span>";
    }
    return '';
});