Is there are way to combine "is" and "as" in C#

Question

Possible Duplicate:
C# - Assignment in an if statement

I find my myself doing the following multiple time

if (e.row.FindControl("myLiteral") is Literal)
{
    (e.row.FindControl("myLiteral") as Literal).Text = "textData";
}

Is there way to replace the "if" part and simplify the setter:

(e.row.FindControl("myLiteral") <some operator that combines is and as> .text = "textData";

EDIT: I should have mentioned this before- I want to remove the 'if' entirely.
"some operator " should do this internally and set the ".text" only if e.row.FindControl is a literal

`as` already does an `is` for you and returns null if something `is` not a certain type. — BoltClock, Sep 19 '11 at 22:01
heh, MS heard me - for future Reference: (e.row.FindControl("myLiteral"))??.text =="TextData"; — Bitmask, Apr 02 '17 at 02:17

score 6 · Answer 1 · answered Sep 19 '11 at 22:01

6

Normally I wouldn't combine them like that to start with - I'd either use a cast or I'd use as and a null check:

Literal literal = e.row.FindControl("myLiteral") as Literal;
if (literal != null)
{
    literal.Text = "textData";
}

answered Sep 19 '11 at 22:01

Jon Skeet

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score 2 · Answer 2 · answered Sep 19 '11 at 22:04

There is no built-in way to do this. However you could author an extension method which gives you this capability

public static void AsType<T>(object o, Action<T> action) where T : class
{
    var value = o as T;
    if (value != null)
    {
        action(value);
    }
}

You could then write

e.row.FindControl("myLiteral").AsType<Literal>(l => l.Text = "textData");

score 1 · Answer 3 · answered Sep 19 '11 at 22:02

the as operator already does an is. If the cast succeed it returns the casted value, otherwise it returns null.

Literal lit = e.row.FindControl("myLiteral") as Literal;
if (lit != null)
{
    lit.Text = "textData";
}

or

if (e.row.FindControl("myLiteral") is Literal)
{
    Literal lit = (Literal)e.row.FindControl("myLiteral");
    lit.Text = "textData";
}

score 1 · Answer 4 · edited May 23 '17 at 12:17

1

A check using is is typically followed by a cast:

if (e.row.FindControl("myLiteral") is Literal)
{
    ((Literal)e.row.FindControl("myLiteral")).Text = "textData";
}

Whereas as functions as such a check that returns either a successfully cast instance or null to the assigned variable, which you can then check for null (See @Jon Skeet's answer).

edited May 23 '17 at 12:17

Community

1
1

answered Sep 19 '11 at 22:02

Paul Bellora

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score 0 · Answer 5 · answered Sep 19 '11 at 22:02

0

You could do:

var literal = e.row.FindControl("myLiteral") as Literal;
if (literal != null)
{
    literal.Text = "textData";
}

answered Sep 19 '11 at 22:02

Darin Dimitrov

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score 0 · Answer 6 · answered Sep 19 '11 at 22:04

Well, you could use as more like this (the standard usage):

Literal lit = e.row.FindControl("myLiteral") as Literal;
if (lit != null) {
  lit.Text = "textData";
}

If you're using .Net 3.5 or greater you could create an extension method to handle this (kind of):

internal static class Extensions {
  internal static void SetTextLiteral(this Control c, string text) {
    Literal lit = c as Literal;
    if (lit != null)
      lit.Text = text;
  }
}

void Sample() {
  e.row.FindControl("myLiteral").SetTextLiteral("textData");
}

Is there are way to combine "is" and "as" in C#

6 Answers6