Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>I might be missing something but your design doesn't make much sense to me. </p> <p>As I see it, extending a <code>streambuf</code> is done by overriding the protected virtual interface, if you'd want to use a decorator pattern your decorator base class would do just that.</p> <pre><code>template&lt;typename char_type, class traits_type&gt; class forwarding_basic_streambuf : boost::noncopyable, public std::basic_streambuf&lt;char_type, traits_type&gt; { public: typedef std::basic_streambuf&lt;char_type, traits_type&gt; forwarded_type; forwarding_basic_streambuf(forwarded_type&amp; fwd_buf) : m_fwd(&amp;fwd_buf) { } virtual ~forwarding_basic_streambuf() { } protected: virtual streamsize xsputn ( const char * s, streamsize n ) { m_fwd-&gt;xsputn(s,n); } virtual int overflow ( int c) { m_fwd-&gt;overflow(c); } // etc. }; </code></pre> <p>You real implementation would then add any needed 'decorations' e.g.</p> <pre><code>template&lt;typename char_type, class traits_type&gt; class add_timestamp_decorator : public forwarding_basic_streambuf&lt;char_type, traits_type&gt; { public: typedef std::forwarding_basic_streambuf&lt;char_type, traits_type&gt; base_type; add_timestamp_decorator(base_type::forwarded_type&amp; fwd_buf) : base_type(&amp;fwd_buf) { } virtual ~add_timestamp_decorator() { } protected: virtual streamsize xsputn ( const char * s, streamsize n ) { // detect and remember when a newline is written // before the next char is written output the timestamp base_type::xsputn(s, n); } // etc. }; </code></pre> <p>And then use it on an outputstream (pseudo code, omitted template definitions for clarity)</p> <pre><code>ostream outputstream; // .... add_timestamp_decorator decorator = new add_timestamp_decorator(outputstream.rdbuf()); outputstream.rdbuf(decorator); outputstream &lt;&lt; "some lines\ntimestamps will be inserted\n\n"; </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POC++ Decorate basic_stream::underflow()
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. USPieter
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThanks for your answer. That usage could lead into unintended behavior. Please consider a situation where you want to do something before it`s actually `read` from the underlying device. You could use `sbumpc` to read a single character at a time. However, that won`t do what it should. So, I would need to override `uflow` in a way I showed in my answer. I omitted any decorating code for simplicity. But I want to use my decorator as if it were the decorated object itself.
      singulars
      1. PO
      1. US0xbadf00d
    2. COBtw: `overflow()` and `underflow` will be called all the time when you read or write by using the decorator, because it`s own read/write buffer is always empty.
      singulars
      1. PO
      1. US0xbadf00d
    3. CO@FrEEzE2046 If you want to fundamentally change the underlying behaviour, I don't think you should use the decorator pattern, but simply create a subclass and override / change the behaviour of the class
      singulars
      1. PO
      1. USPieter
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload