The “?” and “!” characters are not doing something special on their own. It’s just that you can include them in the name of your methods if you want. It’s only a convention to use the “?” character in methods that does nothing worth of mention other than returning yes or no. As it’s just a convention to use the “!” character in methods that do something destructive or “dangerous”. You could (but should not) use them for other purpose.

So, if you want to write : if my_method? …

You would have to define it this way :

def my_method?
return true #or false, or anything you want
end

If you want to write : destroy!

You would have to define it this way :

def destroy!
#Do something destructive like deleting all rows of a table in a DB
end

I hope it does answer your question

So how do you do your own method like that?

For: ?
def method
return true or false
end

if method?
#do that
end

For: !

def method
raise “exception”
end

method!
rescue “exception”

or something like that?

Can you tell us how to use both ! or ? or nothing ?, a article/post about methods will be really great :D

sounds pretty nice