From: Matthias Lampert <ml@...>
Date: 2001-08-17T22:36:54+09:00
Subject: [ruby-talk:19942]


Hi, folks!

It sounds like traveling to Rio via North and South Pole, I know, 
but ... has anyone of you ever tried to build the Mysql-extension
for Ruby on cygwin?

The trouble is, that the linker is unable to find the references 
for the MySQL  C API. These are the first lines I get:

dllwrap --target=cygwin --as=as --dlltool-name=dlltool --driver-name=gcc 
--export-all -s --def=mysql.def -L/usr/local/lib/ruby/1.6/i686-cygwin 
-L/usr/local/lib  -o mysql.so mysql.o -L. -lcygwin-ruby16   
-L/cygdrive/c/mysql/lib/opt -lmysqlclient 
mysql.o: In function `free_mysql':
/cygdrive/c/upload/mysql-ruby-2.3.2a/mysql.c:61: undefined reference to
`mysql_close'
mysql.o: In function `free_mysqlres':
/cygdrive/c/upload/mysql-ruby-2.3.2a/mysql.c:68: undefined reference to
`mysql_free_result'
mysql.o: In function `mysql_raise':
/cygdrive/c/upload/mysql-ruby-2.3.2a/mysql.c:76: undefined reference to
`mysql_error'




> -----Original Message-----
> From: Stephen White [mailto:spwhite@chariot.net.au]
> Sent: Friday, August 17, 2001 3:01 PM
> To: ruby-talk@ruby-lang.org
> Subject: [ruby-talk:19939] Re: Why not?: Assigning to self
> 
> 
> Pit Capitain wrote:
> > Why not? In this class hierarchy each square is a (specialized) 
> > rectangle, so class Square also has a method #set_shape. If 
> > called with width != height, the Square instance would "become" a 
> > Rectangle instance. In a drawing program showing a square, why 
> > shouldn't it make sense to be able to drag one side or one hotspot 
> > in order to change the square into a rectangle?
> 
> That would mean that #set_shape in Square would have to 
> handle all the 
> possible parameters for Rectangle, Circle, Ellipse, Triangle, 
> Star, and 
> so on. I don't like this degree of interdependence.
> 
> You can implement this in Ruby with something like:
> 
>    class Square
>      def set_shape(x, y) # note the "y" only exists because 
> of Rectangle
>        if x != y
>          Rectangle.new(x,y) # Square knows about Rectangle, 
> bad coding!
>        else
>          @x, @y = x, y
>          self
>        end
>      end
>    end
> 
>    item = shape.set_shape(10, 10)
>    item = shape.set_shape(23, 45)
> 
> It would be better to abstract this up a level, so a "Shapes" class 
> would know about all the possible shapes underneath it, and 
> thus has a 
> legitimate reason for knowing the different parameters.
> 
> The bonus side of this is that you will no longer have any need for 
> "become".
> 
> -- 
>    spwhite@chariot.net.au
>