Lookup constants based on object names

Simon Bennetts

Hi,

I have a windows application which places default / help values in empty text boxes on the form in gray to show the user what is supposed to be entered (e.g. FORENAME in my txtForename textbox) in the textbox.

I have a generic event for all my textboxes on Enter to remove the text, change back from gray and add the change event. On exit, I'm checking if they've entered anything and would like to refill the textbox with it's default value if they've left it blank or delete it later.

I have a ParametersDefaults class which contains a list of constants with the same name as the text box objects (e.g. public const string txtForename = "FORENAME").

What I want to do is get that string value based on the sender object (which will always be a text box).

Something along the lines of

((TextBox)sender).Text = DefaultParameters.[sender.Name bit goes here!]

I'm sure there must be an easy way but I can't figure it out and it's only Tuesday!

Thanks in advance

Simon

2 Replies

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Vulpes12y ago
Accepted answer
If the name of the textbox always contains its full name, rather than an abbreviation, then an easy way to do this would be:

TextBox tb = (TextBox)sender;
tb.Text = tb.Name.Replace("txt", "").ToUpper();

Otherwise I'd be inclined to use a Dictionary rather than your 'list of constants' approach. However, if you want to stick with the latter, you can still do it using reflection:

using System.Reflection;

// ...

TextBox tb = (TextBox)sender;
Type t = typeof(DefaultParameters);
BindingFlags bf = BindingFlags.Static | BindingFlags.Public;
FieldInfo fi = t.GetField(tb.Name, bf);
tb.Text = fi.GetValue(null).ToString();
Simon Bennetts12y ago
Thanks for the quick reply. Dictonary replacement using the actual name with the txt removed won't always work as some will be different and also have illegal characters like spaces or slashes.

Your solutions works though, thank you!

Thanks
Simon