Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Probably the closest Delphi analogue to <code>std::vector&lt;T&gt;</code> is <a href="http://docwiki.embarcadero.com/Libraries/en/System.Generics.Collections.TList" rel="noreferrer"><code>TList&lt;T&gt;</code></a>. You can iterate over the list with a <a href="http://docwiki.embarcadero.com/RADStudio/en/Declarations_and_Statements#Iteration_Over_Containers_Using_For_statements" rel="noreferrer"><code>for in</code></a> loop:</p> <pre><code>var Item: Integer; List: TList&lt;Integer&gt;; .... for Item in List do Writeln(Item); </code></pre> <p>If you have a dynamic array rather than a <code>TList&lt;T&gt;</code> then you can use <code>for in</code> to iterate over the elements. In fact, all the built in containers support <code>for in</code> and it is easy to add support for <code>for in</code> to your own classes.</p> <p>In C++ there is nothing like a <code>for in</code> loop and so the idiom is to use an STL algorithm. That's what drives you to using an anonymous function. In Delphi with the <code>for in</code> syntax you can express "iterate over all members of the container" in a natural way without resorting to anonymous methods.</p> <p>Generics were added to Delphi in Delphi 2009 and the <code>for in</code> loop was added in Delphi 2005, so all this is available to you in XE. For what it's worth, anonymous were also added in Delphi 2009.</p> <p>What you must realise is that Delphi generics are less powerful than C++ templates. Although you talk about a generic <code>foreach</code>, your code is not generic in the sense that it has specialised to <code>int</code>. You could write a generic version of your code in C++ but this would be much harder to do with Delphi generics due to the inherent limitations of generics when compared to templates. An attempt to write the above code in a generic way in Delphi would founder at the point where you tried to call <code>Writeln</code>. Whilst that would be trivial with C++ templates it is frustratingly out of reach for generics.</p> <p><strong>Update:</strong> In the comments you ask if there is a slick way to add the contents of one container to another. The <a href="http://docwiki.embarcadero.com/Libraries/en/System.Generics.Collections.TList.AddRange" rel="noreferrer"><code>AddRange</code></a> method does that. <code>TList&lt;T&gt;.AddRange()</code> has three overloaded variants that receive one of the following input parameters: <code>array of T</code>, <code>Collection: IEnumerable&lt;T&gt;</code> or <code>Collection: TEnumerable&lt;T&gt;</code>. All the standard generic containers follow a similar pattern.</p>
    singulars
    1. This table or related slice is empty.
    1. POIs there a foreach generic method in Delphi for that can be called with anonymous function
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USDavid Heffernan
    1. USDavid Heffernan
    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
    1. COThat's how I did it: for i := 0 to n - 1 do result.Add(i); But I was wondering whether such generic function existed :)
      singulars
      1. PO
      1. USMihaela
    2. COLambda/Closure/Anonfunction syntax is so CLUNKY in delphi that it's pretty great that you don't need it for `for` loops. C++ idioms as usual, don't translate well to pascal. But C# and Delphi are pretty close indeed.
      singulars
      1. PO
      1. USWarren P
    3. COI find it quite useful in C++. Not only is the code cleaner(for small anonymous functions), but in C++ it often gets inlined and generates faster code.
      singulars
      1. PO
      1. USMihaela
 

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