From: Tobias Reif <tobiasreif@...>
Date: 2002-01-28T08:06:42+09:00
Subject: Re: how to find out which args a method can take

Dave Thomas wrote:

> Tobias Reif <tobiasreif@pinkjuice.com> writes:
> 
>>I know that I can pass wide varieties to some methods. What I thought 
>>was: perhaps there are any built-in documentation like info bits that 
>>can help whan generating "tests" for built-in methiods. Something like
>>Array.works_with_args?('join')    # -> [[String]]
>>String.works_with_args('sub')     # -> [[Regex,String], [Regex, Block]]
>>String.works_with_args('reverse') # -> []
>>
> But... Ruby classes are not types in this sense


Is the above depending on this? I don't get what you mean :|

A human can see what built-in methods can take by looking @ 
documentation like

sub
str.sub( pattern, replacement ) -> aString
str.sub( pattern ) {| match | block } -> aString

So now I would like my program to be able to get the same information 
(as far as possible) from perhaps some class method.

> (although admittedly
> it works 99% of the time). For example,
> 
>   irbsh(main):001:0> e = Exception.new("hello")
>   #<Exception: hello>
>   irbsh(main):002:0> "123".sub(/./, e)
>   "hello23"


Could you be so kind and explain the above to me?


> You _could_ find out some of the information you need by trying things
> and catching the TypeError exception, but that seems like a lot of
> work :)


... or a lot of fun? :)

Nah. I'd like to ask the method.


Tobi


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