Type conversions for DefaultValue property

[mylady]

hi,
i'm new to this libray and i followed instructions in the wiki
just do some simple test and i'm confused with the default value and metavalue
for example

 [Option('i', "ip", HelpText = "set remote server ip", DefaultValue = "127.0.0.1")]
 public string RemoteIPAddress { set; get; }

 [Option('r', "remote", HelpText = "set remote server port, tcp protocol like", DefaultValue = 8000u)]
 public uint RemotePort { set; get; }

if i change type of RemoteIPAddress to IPAddress,there will be an exception report bad default value string can't be coverted to IPAddress,but for the attribute value ,IPAddress.Any or IPAddress.Loopback can't be set because they are static value

then as the type uint,if i set DefaultValue of RemotePort to 8000,it also cause exception that int can't be converted to uint even if i set MetaValue to "uint"

i dont't quite get it ,any help will be appreciated

[nemec]

Hi @mylady, you're right - this library doesn't yet support custom type converters.
To accomplish what you want, you can set the default IPAddress.Any in the constructor of your options class. It's not a complete replacement for DefaultValue's behavior, but if all you want to do is provide a non-null default value if -i is not specified, it should work for you.

The uint issue is odd. Since you're using a uint literal in your definition, it should be working fine. In fact, I just tested in LINQPad by copy and pasting your RemotePort property above and it works for me!

[mylady]

@nemec thx for your help
for the uint DefaultValue,I mean if I set DeafaultValue to 8000(int),it will cause exception
and if MetaValue means the type name of the Property,even if i set MetaValue to uint,and set DefaultValue to 8000 it will also throw exception

In my point of view,if i can declear the exact type of the value, the command line parser should
do the type validation for me or provide a way to validate it.

Take IPAddress for example:
I can use type string to hold the value but i have to make sure the input value is a valid IPAddress not some bad value like "123" or "abc".If i specify this argument's type in custom option class to IPAddress, both valid value like '192.168.1.1' or invalid value "123" will cause parse failure .This makes
type declearation meaningless

So i think if the type conversion should be provided for at least some common system type(may be it has ready been done but i dont't see it work) and for the custom type you could add a basic validator for developers to extends and call it during the process of argument parse,after all it's all strings ,yes?

[nemec]

I agree, type conversions for the DefaultValue property would be a great feature. It's not supported right now, though.