Updating a collection using a lambda

[Paul Prewett]

Hi -

I have a situation where I'd like to use a lambda, but I'm not sure how.
Basically, I have a collection of objects and I want to set a property on
each object that meets a condition.

Right now, I have this:

IEnumerable<VariableCode> codes =
variable.VariableCodeList.Where(c => c.Type == "MyCondition");
foreach (VariableCode code in codes)
{
code.IsShown = true;
}//foreach

I'm thinking that I can replace the foreach bit with a single lambda
expression. Can anyone help me with that syntax?

Thanks.

 

[Jon Skeet [C# MVP]]

I have a situation where I'd like to use a lambda, but I'm not sure how.
Basically, I have a collection of objects and I want to set a property on
each object that meets a condition.

Right now, I have this:

IEnumerable<VariableCode> codes =
variable.VariableCodeList.Where(c => c.Type == "MyCondition");
foreach (VariableCode code in codes)
{
code.IsShown = true;
}//foreach

I'm thinking that I can replace the foreach bit with a single lambda
expression. Can anyone help me with that syntax?

Well, if you use List<T> instead, you can use List.ForEach.

Alternatively, you could (somewhat evilly) do:

var codes = from variable.VariableCodeList
where c.Type=="MyCondition"
select { c.IsShown=true; return c; } ;

(In other words, make the change part of the projection.)

Or you could write a ForEach extension method yourself - it would be
trivial to do.

 

[Paul Prewett]

Hm, yes.

Well, VariableCodeList is actually a List<T>, but once I do the Where(), I
am stuck with IEnumerable<T>.

I'm thinking I'll just leave it the way that it is.

Thanks for the input, though.

 

[Jon Skeet [C# MVP]]

Well, VariableCodeList is actually a List<T>, but once I do the Where(), I
am stuck with IEnumerable<T>.

You can always call ToList() to get another List if you want.

 

[Paul Prewett]

Ah. There we go.

Thankee, sai.