Matrix modifying and coercion question?

ruby-talk
1

Hi,
I was wondering why Ruby Matrix class doesn't creates objects which are
editable?

That is,
m = Matrix[[2,3,4]]
m[0,0]= 5
NoMethodError: undefined method `=' for Matrix[[2, 3, 4]]:Matrix
  from (irb):11
gives error,

as a workaround I have seen people/myself opened the matrix class and defined the
'=' method such that, '@rows' variable is edited.

    def =(i,j,val)
      @rows[i][j] = val
    end

Is it safe to do this?
Ditto for the Vector class? why are objects of these classes not editable?

Second, if I want to change the class of an object? Is it possible to do so?
Say, I want an object of Matrix class to automatically changed to DMatrix,
which is a derived class, then how do I do so?

Thanks for your help.

Regards,

···

--
Surendra Singhi
http://ssinghi.kreeti.com, http://www.kreeti.com
Read my blog at: http://cuttingtheredtape.blogspot.com/
,----

Great wits are sure to madness near allied,
And thin partitions do their bounds divide.

    (John Dryden, Absalom and Achitophel, 1681)

`----

2

Hi,
I know it is bad posting on one’s own email, but I didn’t get any answer. I
feel these are reasonable questions to ask. Please help.

Regards,

Surendra Singhi efuzzyone@netscape.net writes:

···

Hi,
I was wondering why Ruby Matrix class doesn’t creates objects which are
editable?

That is,
m = Matrix[[2,3,4]]
m[0,0]= 5
NoMethodError: undefined method `=’ for Matrix[[2, 3, 4]]:Matrix
from (irb):11
gives error,

as a workaround I have seen people/myself opened the matrix class and defined the
‘=’ method such that, ‘@rows’ variable is edited.

def []=(i,j,val)
  @rows[i][j] = val
end

Is it safe to do this?
Ditto for the Vector class? why are objects of these classes not editable?

Second, if I want to change the class of an object? Is it possible to do so?
Say, I want an object of Matrix class to automatically changed to DMatrix,
which is a derived class, then how do I do so?

Thanks for your help.

–
Surendra Singhi
http://ssinghi.kreeti.com, http://www.kreeti.com
Read my blog at: http://cuttingtheredtape.blogspot.com/
,----

“War is Peace! Freedom is Slavery! Ignorance is Strength!”
– Orwell, 1984, 1948
`----