Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>Delphi For in loop support requires on of the following: (<a href="http://docwiki.embarcadero.com/RADStudio/en/E2430_for-in_statement_cannot_operate_on_collection_type_&#39;%25s&#39;_(Delphi)" rel="nofollow noreferrer">From the Docs</a>)</p> <ul> <li>Primitive types that the compiler recognizes, such as arrays, sets or strings </li> <li>Types that implement IEnumerable </li> <li>Types that implement the GetEnumerator pattern as documented in the Delphi Language Guide</li> </ul> <p>If you look at Generics.Collections.pas you will find the implementation for <code>TDictionary&lt;TKey,TValue&gt;</code> where it has three enumerators for <code>TKey</code>, <code>TValue</code>, and <code>TPair&lt;TKey,TValue&gt;</code> types. Embarcadero shows that they have used verbose implementation.</p> <p>You could do something like this:</p> <pre><code>unit Generics.AnonEnum; interface uses SysUtils, Generics.Defaults, Generics.Collections; type TAnonEnumerator&lt;T&gt; = class(TEnumerator&lt;T&gt;) protected FGetCurrent : TFunc&lt;TAnonEnumerator&lt;T&gt;,T&gt;; FMoveNext : TFunc&lt;TAnonEnumerator&lt;T&gt;,Boolean&gt;; function DoGetCurrent: T; override; function DoMoveNext: Boolean; override; public Constructor Create(aGetCurrent : TFunc&lt;TAnonEnumerator&lt;T&gt;,T&gt;; aMoveNext : TFunc&lt;TAnonEnumerator&lt;T&gt;,Boolean&gt;); end; TAnonEnumerable&lt;T&gt; = class(TEnumerable&lt;T&gt;) protected FGetCurrent : TFunc&lt;TAnonEnumerator&lt;T&gt;,T&gt;; FMoveNext : TFunc&lt;TAnonEnumerator&lt;T&gt;,Boolean&gt;; function DoGetEnumerator: TEnumerator&lt;T&gt;; override; public Constructor Create(aGetCurrent : TFunc&lt;TAnonEnumerator&lt;T&gt;,T&gt;; aMoveNext : TFunc&lt;TAnonEnumerator&lt;T&gt;,Boolean&gt;); end; implementation { TEnumerable&lt;T&gt; } constructor TAnonEnumerable&lt;T&gt;.Create(aGetCurrent: TFunc&lt;TAnonEnumerator&lt;T&gt;, T&gt;; aMoveNext: TFunc&lt;TAnonEnumerator&lt;T&gt;, Boolean&gt;); begin FGetCurrent := aGetCurrent; FMoveNext := aMoveNext; end; function TAnonEnumerable&lt;T&gt;.DoGetEnumerator: TEnumerator&lt;T&gt;; begin result := TAnonEnumerator&lt;T&gt;.Create(FGetCurrent,FMoveNext); end; { TAnonEnumerator&lt;T&gt; } constructor TAnonEnumerator&lt;T&gt;.Create(aGetCurrent: TFunc&lt;TAnonEnumerator&lt;T&gt;, T&gt;; aMoveNext: TFunc&lt;TAnonEnumerator&lt;T&gt;, Boolean&gt;); begin FGetCurrent := aGetCurrent; FMoveNext := aMoveNext; end; function TAnonEnumerator&lt;T&gt;.DoGetCurrent: T; begin result := FGetCurrent(self); end; function TAnonEnumerator&lt;T&gt;.DoMoveNext: Boolean; begin result := FMoveNext(Self); end; end. </code></pre> <p>This would allow you declare your Current and MoveNext methods anonymously.</p>
    singulars
    1. This table or related slice is empty.
    1. POBetter way to implement filtered enumerator on TList<TMyObject>
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. USRobert Love
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POBetter way to implement filtered enumerator on TList<TMyObject>
      singulars
      1. PTQuestion
    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. VTAcceptedByOriginator
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COThe idea of using anonymous methods to implement the enumerator is absolutely brilliant, it saves me from creating countless classes to implement different enumerators. After all the enumerator's code is usually pretty simple and it can be implemented in just a few lines of code. Thank you.
      singulars
      1. PO
      1. USCosmin Prund
 

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